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authorLinus Torvalds <torvalds@linux-foundation.org>2020-10-18 14:34:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-18 14:34:50 -0700
commit41eea65e2aaadc0611fd56a1b177ce25dcc4c1df (patch)
tree75a923658e76b40792db00c79ff2f115b07b963a /kernel
parent373014bb517e0bb291714fe1e232fb606d54931b (diff)
parentb36c830f8c9b13bfe69b117e879153776c19ad82 (diff)
downloadlinux-41eea65e2aaadc0611fd56a1b177ce25dcc4c1df.tar.gz
Merge tag 'core-rcu-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU changes from Ingo Molnar: - Debugging for smp_call_function() - RT raw/non-raw lock ordering fixes - Strict grace periods for KASAN - New smp_call_function() torture test - Torture-test updates - Documentation updates - Miscellaneous fixes [ This doesn't actually pull the tag - I've dropped the last merge from the RCU branch due to questions about the series. - Linus ] * tag 'core-rcu-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (77 commits) smp: Make symbol 'csd_bug_count' static kernel/smp: Provide CSD lock timeout diagnostics smp: Add source and destination CPUs to __call_single_data rcu: Shrink each possible cpu krcp rcu/segcblist: Prevent useless GP start if no CBs to accelerate torture: Add gdb support rcutorture: Allow pointer leaks to test diagnostic code rcutorture: Hoist OOM registry up one level refperf: Avoid null pointer dereference when buf fails to allocate rcutorture: Properly synchronize with OOM notifier rcutorture: Properly set rcu_fwds for OOM handling torture: Add kvm.sh --help and update help message rcutorture: Add CONFIG_PROVE_RCU_LIST to TREE05 torture: Update initrd documentation rcutorture: Replace HTTP links with HTTPS ones locktorture: Make function torture_percpu_rwsem_init() static torture: document --allcpus argument added to the kvm.sh script rcutorture: Output number of elapsed grace periods rcutorture: Remove KCSAN stubs rcu: Remove unused "cpu" parameter from rcu_report_qs_rdp() ...
Diffstat (limited to 'kernel')
-rw-r--r--kernel/Makefile2
-rw-r--r--kernel/entry/common.c2
-rw-r--r--kernel/locking/locktorture.c2
-rw-r--r--kernel/rcu/Kconfig8
-rw-r--r--kernel/rcu/Kconfig.debug17
-rw-r--r--kernel/rcu/Makefile2
-rw-r--r--kernel/rcu/rcu_segcblist.c10
-rw-r--r--kernel/rcu/rcuscale.c (renamed from kernel/rcu/rcuperf.c)330
-rw-r--r--kernel/rcu/rcutorture.c61
-rw-r--r--kernel/rcu/refscale.c8
-rw-r--r--kernel/rcu/srcutree.c13
-rw-r--r--kernel/rcu/tree.c165
-rw-r--r--kernel/rcu/tree.h2
-rw-r--r--kernel/rcu/tree_exp.h6
-rw-r--r--kernel/rcu/tree_plugin.h40
-rw-r--r--kernel/rcu/tree_stall.h8
-rw-r--r--kernel/rcu/update.c13
-rw-r--r--kernel/scftorture.c575
-rw-r--r--kernel/smp.c134
-rw-r--r--kernel/time/tick-sched.c2
20 files changed, 1109 insertions, 291 deletions
diff --git a/kernel/Makefile b/kernel/Makefile
index e5bc66a94b70..2044ef02763b 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -134,6 +134,8 @@ KASAN_SANITIZE_stackleak.o := n
KCSAN_SANITIZE_stackleak.o := n
KCOV_INSTRUMENT_stackleak.o := n
+obj-$(CONFIG_SCF_TORTURE_TEST) += scftorture.o
+
$(obj)/configs.o: $(obj)/config_data.gz
targets += config_data.gz
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 145ab11b8318..0a1e20f8d4e8 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -304,7 +304,7 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
* terminate a grace period, if and only if the timer interrupt is
* not nested into another interrupt.
*
- * Checking for __rcu_is_watching() here would prevent the nesting
+ * Checking for rcu_is_watching() here would prevent the nesting
* interrupt to invoke rcu_irq_enter(). If that nested interrupt is
* the tick then rcu_flavor_sched_clock_irq() would wrongfully
* assume that it is the first interupt and eventually claim
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 9cfa5e89cff7..62d215b2e39f 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -566,7 +566,7 @@ static struct lock_torture_ops rwsem_lock_ops = {
#include <linux/percpu-rwsem.h>
static struct percpu_rw_semaphore pcpu_rwsem;
-void torture_percpu_rwsem_init(void)
+static void torture_percpu_rwsem_init(void)
{
BUG_ON(percpu_init_rwsem(&pcpu_rwsem));
}
diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig
index 0ebe15a84985..b71e21f73c40 100644
--- a/kernel/rcu/Kconfig
+++ b/kernel/rcu/Kconfig
@@ -135,10 +135,12 @@ config RCU_FANOUT
config RCU_FANOUT_LEAF
int "Tree-based hierarchical RCU leaf-level fanout value"
- range 2 64 if 64BIT
- range 2 32 if !64BIT
+ range 2 64 if 64BIT && !RCU_STRICT_GRACE_PERIOD
+ range 2 32 if !64BIT && !RCU_STRICT_GRACE_PERIOD
+ range 2 3 if RCU_STRICT_GRACE_PERIOD
depends on TREE_RCU && RCU_EXPERT
- default 16
+ default 16 if !RCU_STRICT_GRACE_PERIOD
+ default 2 if RCU_STRICT_GRACE_PERIOD
help
This option controls the leaf-level fanout of hierarchical
implementations of RCU, and allows trading off cache misses
diff --git a/kernel/rcu/Kconfig.debug b/kernel/rcu/Kconfig.debug
index 3cf6132a4bb9..1942c1f1bb65 100644
--- a/kernel/rcu/Kconfig.debug
+++ b/kernel/rcu/Kconfig.debug
@@ -23,7 +23,7 @@ config TORTURE_TEST
tristate
default n
-config RCU_PERF_TEST
+config RCU_SCALE_TEST
tristate "performance tests for RCU"
depends on DEBUG_KERNEL
select TORTURE_TEST
@@ -114,4 +114,19 @@ config RCU_EQS_DEBUG
Say N here if you need ultimate kernel/user switch latencies
Say Y if you are unsure
+config RCU_STRICT_GRACE_PERIOD
+ bool "Provide debug RCU implementation with short grace periods"
+ depends on DEBUG_KERNEL && RCU_EXPERT
+ default n
+ select PREEMPT_COUNT if PREEMPT=n
+ help
+ Select this option to build an RCU variant that is strict about
+ grace periods, making them as short as it can. This limits
+ scalability, destroys real-time response, degrades battery
+ lifetime and kills performance. Don't try this on large
+ machines, as in systems with more than about 10 or 20 CPUs.
+ But in conjunction with tools like KASAN, it can be helpful
+ when looking for certain types of RCU usage bugs, for example,
+ too-short RCU read-side critical sections.
+
endmenu # "RCU Debugging"
diff --git a/kernel/rcu/Makefile b/kernel/rcu/Makefile
index 95f5117ef8da..0cfb009a99b9 100644
--- a/kernel/rcu/Makefile
+++ b/kernel/rcu/Makefile
@@ -11,7 +11,7 @@ obj-y += update.o sync.o
obj-$(CONFIG_TREE_SRCU) += srcutree.o
obj-$(CONFIG_TINY_SRCU) += srcutiny.o
obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
-obj-$(CONFIG_RCU_PERF_TEST) += rcuperf.o
+obj-$(CONFIG_RCU_SCALE_TEST) += rcuscale.o
obj-$(CONFIG_RCU_REF_SCALE_TEST) += refscale.o
obj-$(CONFIG_TREE_RCU) += tree.o
obj-$(CONFIG_TINY_RCU) += tiny.o
diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c
index 9a0f66133b4b..2d2a6b6b9dfb 100644
--- a/kernel/rcu/rcu_segcblist.c
+++ b/kernel/rcu/rcu_segcblist.c
@@ -475,8 +475,16 @@ bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq)
* Also advance to the oldest segment of callbacks whose
* ->gp_seq[] completion is at or after that passed in via "seq",
* skipping any empty segments.
+ *
+ * Note that segment "i" (and any lower-numbered segments
+ * containing older callbacks) will be unaffected, and their
+ * grace-period numbers remain unchanged. For example, if i ==
+ * WAIT_TAIL, then neither WAIT_TAIL nor DONE_TAIL will be touched.
+ * Instead, the CBs in NEXT_TAIL will be merged with those in
+ * NEXT_READY_TAIL and the grace-period number of NEXT_READY_TAIL
+ * would be updated. NEXT_TAIL would then be empty.
*/
- if (++i >= RCU_NEXT_TAIL)
+ if (rcu_segcblist_restempty(rsclp, i) || ++i >= RCU_NEXT_TAIL)
return false;
/*
diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuscale.c
index 21448d3374e2..2819b95479af 100644
--- a/kernel/rcu/rcuperf.c
+++ b/kernel/rcu/rcuscale.c
@@ -1,6 +1,6 @@
// SPDX-License-Identifier: GPL-2.0+
/*
- * Read-Copy Update module-based performance-test facility
+ * Read-Copy Update module-based scalability-test facility
*
* Copyright (C) IBM Corporation, 2015
*
@@ -44,13 +44,13 @@
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
-#define PERF_FLAG "-perf:"
-#define PERFOUT_STRING(s) \
- pr_alert("%s" PERF_FLAG " %s\n", perf_type, s)
-#define VERBOSE_PERFOUT_STRING(s) \
- do { if (verbose) pr_alert("%s" PERF_FLAG " %s\n", perf_type, s); } while (0)
-#define VERBOSE_PERFOUT_ERRSTRING(s) \
- do { if (verbose) pr_alert("%s" PERF_FLAG "!!! %s\n", perf_type, s); } while (0)
+#define SCALE_FLAG "-scale:"
+#define SCALEOUT_STRING(s) \
+ pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s)
+#define VERBOSE_SCALEOUT_STRING(s) \
+ do { if (verbose) pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s); } while (0)
+#define VERBOSE_SCALEOUT_ERRSTRING(s) \
+ do { if (verbose) pr_alert("%s" SCALE_FLAG "!!! %s\n", scale_type, s); } while (0)
/*
* The intended use cases for the nreaders and nwriters module parameters
@@ -61,25 +61,25 @@ MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
* nr_cpus for a mixed reader/writer test.
*
* 2. Specify the nr_cpus kernel boot parameter, but set
- * rcuperf.nreaders to zero. This will set nwriters to the
+ * rcuscale.nreaders to zero. This will set nwriters to the
* value specified by nr_cpus for an update-only test.
*
* 3. Specify the nr_cpus kernel boot parameter, but set
- * rcuperf.nwriters to zero. This will set nreaders to the
+ * rcuscale.nwriters to zero. This will set nreaders to the
* value specified by nr_cpus for a read-only test.
*
* Various other use cases may of course be specified.
*
* Note that this test's readers are intended only as a test load for
- * the writers. The reader performance statistics will be overly
+ * the writers. The reader scalability statistics will be overly
* pessimistic due to the per-critical-section interrupt disabling,
* test-end checks, and the pair of calls through pointers.
*/
#ifdef MODULE
-# define RCUPERF_SHUTDOWN 0
+# define RCUSCALE_SHUTDOWN 0
#else
-# define RCUPERF_SHUTDOWN 1
+# define RCUSCALE_SHUTDOWN 1
#endif
torture_param(bool, gp_async, false, "Use asynchronous GP wait primitives");
@@ -88,16 +88,16 @@ torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
torture_param(int, nreaders, -1, "Number of RCU reader threads");
torture_param(int, nwriters, -1, "Number of RCU updater threads");
-torture_param(bool, shutdown, RCUPERF_SHUTDOWN,
- "Shutdown at end of performance tests.");
+torture_param(bool, shutdown, RCUSCALE_SHUTDOWN,
+ "Shutdown at end of scalability tests.");
torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable");
-torture_param(int, kfree_rcu_test, 0, "Do we run a kfree_rcu() perf test?");
+torture_param(int, kfree_rcu_test, 0, "Do we run a kfree_rcu() scale test?");
torture_param(int, kfree_mult, 1, "Multiple of kfree_obj size to allocate.");
-static char *perf_type = "rcu";
-module_param(perf_type, charp, 0444);
-MODULE_PARM_DESC(perf_type, "Type of RCU to performance-test (rcu, srcu, ...)");
+static char *scale_type = "rcu";
+module_param(scale_type, charp, 0444);
+MODULE_PARM_DESC(scale_type, "Type of RCU to scalability-test (rcu, srcu, ...)");
static int nrealreaders;
static int nrealwriters;
@@ -107,12 +107,12 @@ static struct task_struct *shutdown_task;
static u64 **writer_durations;
static int *writer_n_durations;
-static atomic_t n_rcu_perf_reader_started;
-static atomic_t n_rcu_perf_writer_started;
-static atomic_t n_rcu_perf_writer_finished;
+static atomic_t n_rcu_scale_reader_started;
+static atomic_t n_rcu_scale_writer_started;
+static atomic_t n_rcu_scale_writer_finished;
static wait_queue_head_t shutdown_wq;
-static u64 t_rcu_perf_writer_started;
-static u64 t_rcu_perf_writer_finished;
+static u64 t_rcu_scale_writer_started;
+static u64 t_rcu_scale_writer_finished;
static unsigned long b_rcu_gp_test_started;
static unsigned long b_rcu_gp_test_finished;
static DEFINE_PER_CPU(atomic_t, n_async_inflight);
@@ -124,7 +124,7 @@ static DEFINE_PER_CPU(atomic_t, n_async_inflight);
* Operations vector for selecting different types of tests.
*/
-struct rcu_perf_ops {
+struct rcu_scale_ops {
int ptype;
void (*init)(void);
void (*cleanup)(void);
@@ -140,19 +140,19 @@ struct rcu_perf_ops {
const char *name;
};
-static struct rcu_perf_ops *cur_ops;
+static struct rcu_scale_ops *cur_ops;
/*
- * Definitions for rcu perf testing.
+ * Definitions for rcu scalability testing.
*/
-static int rcu_perf_read_lock(void) __acquires(RCU)
+static int rcu_scale_read_lock(void) __acquires(RCU)
{
rcu_read_lock();
return 0;
}
-static void rcu_perf_read_unlock(int idx) __releases(RCU)
+static void rcu_scale_read_unlock(int idx) __releases(RCU)
{
rcu_read_unlock();
}
@@ -162,15 +162,15 @@ static unsigned long __maybe_unused rcu_no_completed(void)
return 0;
}
-static void rcu_sync_perf_init(void)
+static void rcu_sync_scale_init(void)
{
}
-static struct rcu_perf_ops rcu_ops = {
+static struct rcu_scale_ops rcu_ops = {
.ptype = RCU_FLAVOR,
- .init = rcu_sync_perf_init,
- .readlock = rcu_perf_read_lock,
- .readunlock = rcu_perf_read_unlock,
+ .init = rcu_sync_scale_init,
+ .readlock = rcu_scale_read_lock,
+ .readunlock = rcu_scale_read_unlock,
.get_gp_seq = rcu_get_gp_seq,
.gp_diff = rcu_seq_diff,
.exp_completed = rcu_exp_batches_completed,
@@ -182,23 +182,23 @@ static struct rcu_perf_ops rcu_ops = {
};
/*
- * Definitions for srcu perf testing.
+ * Definitions for srcu scalability testing.
*/
-DEFINE_STATIC_SRCU(srcu_ctl_perf);
-static struct srcu_struct *srcu_ctlp = &srcu_ctl_perf;
+DEFINE_STATIC_SRCU(srcu_ctl_scale);
+static struct srcu_struct *srcu_ctlp = &srcu_ctl_scale;
-static int srcu_perf_read_lock(void) __acquires(srcu_ctlp)
+static int srcu_scale_read_lock(void) __acquires(srcu_ctlp)
{
return srcu_read_lock(srcu_ctlp);
}
-static void srcu_perf_read_unlock(int idx) __releases(srcu_ctlp)
+static void srcu_scale_read_unlock(int idx) __releases(srcu_ctlp)
{
srcu_read_unlock(srcu_ctlp, idx);
}
-static unsigned long srcu_perf_completed(void)
+static unsigned long srcu_scale_completed(void)
{
return srcu_batches_completed(srcu_ctlp);
}
@@ -213,78 +213,78 @@ static void srcu_rcu_barrier(void)
srcu_barrier(srcu_ctlp);
}
-static void srcu_perf_synchronize(void)
+static void srcu_scale_synchronize(void)
{
synchronize_srcu(srcu_ctlp);
}
-static void srcu_perf_synchronize_expedited(void)
+static void srcu_scale_synchronize_expedited(void)
{
synchronize_srcu_expedited(srcu_ctlp);
}
-static struct rcu_perf_ops srcu_ops = {
+static struct rcu_scale_ops srcu_ops = {
.ptype = SRCU_FLAVOR,
- .init = rcu_sync_perf_init,
- .readlock = srcu_perf_read_lock,
- .readunlock = srcu_perf_read_unlock,
- .get_gp_seq = srcu_perf_completed,
+ .init = rcu_sync_scale_init,
+ .readlock = srcu_scale_read_lock,
+ .readunlock = srcu_scale_read_unlock,
+ .get_gp_seq = srcu_scale_completed,
.gp_diff = rcu_seq_diff,
- .exp_completed = srcu_perf_completed,
+ .exp_completed = srcu_scale_completed,
.async = srcu_call_rcu,
.gp_barrier = srcu_rcu_barrier,
- .sync = srcu_perf_synchronize,
- .exp_sync = srcu_perf_synchronize_expedited,
+ .sync = srcu_scale_synchronize,
+ .exp_sync = srcu_scale_synchronize_expedited,
.name = "srcu"
};
static struct srcu_struct srcud;
-static void srcu_sync_perf_init(void)
+static void srcu_sync_scale_init(void)
{
srcu_ctlp = &srcud;
init_srcu_struct(srcu_ctlp);
}
-static void srcu_sync_perf_cleanup(void)
+static void srcu_sync_scale_cleanup(void)
{
cleanup_srcu_struct(srcu_ctlp);
}
-static struct rcu_perf_ops srcud_ops = {
+static struct rcu_scale_ops srcud_ops = {
.ptype = SRCU_FLAVOR,
- .init = srcu_sync_perf_init,
- .cleanup = srcu_sync_perf_cleanup,
- .readlock = srcu_perf_read_lock,
- .readunlock = srcu_perf_read_unlock,
- .get_gp_seq = srcu_perf_completed,
+ .init = srcu_sync_scale_init,
+ .cleanup = srcu_sync_scale_cleanup,
+ .readlock = srcu_scale_read_lock,
+ .readunlock = srcu_scale_read_unlock,
+ .get_gp_seq = srcu_scale_completed,
.gp_diff = rcu_seq_diff,
- .exp_completed = srcu_perf_completed,
+ .exp_completed = srcu_scale_completed,
.async = srcu_call_rcu,
.gp_barrier = srcu_rcu_barrier,
- .sync = srcu_perf_synchronize,
- .exp_sync = srcu_perf_synchronize_expedited,
+ .sync = srcu_scale_synchronize,
+ .exp_sync = srcu_scale_synchronize_expedited,
.name = "srcud"
};
/*
- * Definitions for RCU-tasks perf testing.
+ * Definitions for RCU-tasks scalability testing.
*/
-static int tasks_perf_read_lock(void)
+static int tasks_scale_read_lock(void)
{
return 0;
}
-static void tasks_perf_read_unlock(int idx)
+static void tasks_scale_read_unlock(int idx)
{
}
-static struct rcu_perf_ops tasks_ops = {
+static struct rcu_scale_ops tasks_ops = {
.ptype = RCU_TASKS_FLAVOR,
- .init = rcu_sync_perf_init,
- .readlock = tasks_perf_read_lock,
- .readunlock = tasks_perf_read_unlock,
+ .init = rcu_sync_scale_init,
+ .readlock = tasks_scale_read_lock,
+ .readunlock = tasks_scale_read_unlock,
.get_gp_seq = rcu_no_completed,
.gp_diff = rcu_seq_diff,
.async = call_rcu_tasks,
@@ -294,7 +294,7 @@ static struct rcu_perf_ops tasks_ops = {
.name = "tasks"
};
-static unsigned long rcuperf_seq_diff(unsigned long new, unsigned long old)
+static unsigned long rcuscale_seq_diff(unsigned long new, unsigned long old)
{
if (!cur_ops->gp_diff)
return new - old;
@@ -302,60 +302,60 @@ static unsigned long rcuperf_seq_diff(unsigned long new, unsigned long old)
}
/*
- * If performance tests complete, wait for shutdown to commence.
+ * If scalability tests complete, wait for shutdown to commence.
*/
-static void rcu_perf_wait_shutdown(void)
+static void rcu_scale_wait_shutdown(void)
{
cond_resched_tasks_rcu_qs();
- if (atomic_read(&n_rcu_perf_writer_finished) < nrealwriters)
+ if (atomic_read(&n_rcu_scale_writer_finished) < nrealwriters)
return;
while (!torture_must_stop())
schedule_timeout_uninterruptible(1);
}
/*
- * RCU perf reader kthread. Repeatedly does empty RCU read-side critical
- * section, minimizing update-side interference. However, the point of
- * this test is not to evaluate reader performance, but instead to serve
- * as a test load for update-side performance testing.
+ * RCU scalability reader kthread. Repeatedly does empty RCU read-side
+ * critical section, minimizing update-side interference. However, the
+ * point of this test is not to evaluate reader scalability, but instead
+ * to serve as a test load for update-side scalability testing.
*/
static int
-rcu_perf_reader(void *arg)
+rcu_scale_reader(void *arg)
{
unsigned long flags;
int idx;
long me = (long)arg;
- VERBOSE_PERFOUT_STRING("rcu_perf_reader task started");
+ VERBOSE_SCALEOUT_STRING("rcu_scale_reader task started");
set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
set_user_nice(current, MAX_NICE);
- atomic_inc(&n_rcu_perf_reader_started);
+ atomic_inc(&n_rcu_scale_reader_started);
do {
local_irq_save(flags);
idx = cur_ops->readlock();
cur_ops->readunlock(idx);
local_irq_restore(flags);
- rcu_perf_wait_shutdown();
+ rcu_scale_wait_shutdown();
} while (!torture_must_stop());
- torture_kthread_stopping("rcu_perf_reader");
+ torture_kthread_stopping("rcu_scale_reader");
return 0;
}
/*
- * Callback function for asynchronous grace periods from rcu_perf_writer().
+ * Callback function for asynchronous grace periods from rcu_scale_writer().
*/
-static void rcu_perf_async_cb(struct rcu_head *rhp)
+static void rcu_scale_async_cb(struct rcu_head *rhp)
{
atomic_dec(this_cpu_ptr(&n_async_inflight));
kfree(rhp);
}
/*
- * RCU perf writer kthread. Repeatedly does a grace period.
+ * RCU scale writer kthread. Repeatedly does a grace period.
*/
static int
-rcu_perf_writer(void *arg)
+rcu_scale_writer(void *arg)
{
int i = 0;
int i_max;
@@ -366,7 +366,7 @@ rcu_perf_writer(void *arg)
u64 *wdp;
u64 *wdpp = writer_durations[me];
- VERBOSE_PERFOUT_STRING("rcu_perf_writer task started");
+ VERBOSE_SCALEOUT_STRING("rcu_scale_writer task started");
WARN_ON(!wdpp);
set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
sched_set_fifo_low(current);
@@ -383,8 +383,8 @@ rcu_perf_writer(void *arg)
schedule_timeout_uninterruptible(1);
t = ktime_get_mono_fast_ns();
- if (atomic_inc_return(&n_rcu_perf_writer_started) >= nrealwriters) {
- t_rcu_perf_writer_started = t;
+ if (atomic_inc_return(&n_rcu_scale_writer_started) >= nrealwriters) {
+ t_rcu_scale_writer_started = t;
if (gp_exp) {
b_rcu_gp_test_started =
cur_ops->exp_completed() / 2;
@@ -404,7 +404,7 @@ retry:
rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
if (rhp && atomic_read(this_cpu_ptr(&n_async_inflight)) < gp_async_max) {
atomic_inc(this_cpu_ptr(&n_async_inflight));
- cur_ops->async(rhp, rcu_perf_async_cb);
+ cur_ops->async(rhp, rcu_scale_async_cb);
rhp = NULL;
} else if (!kthread_should_stop()) {
cur_ops->gp_barrier();
@@ -421,19 +421,19 @@ retry:
*wdp = t - *wdp;
i_max = i;
if (!started &&
- atomic_read(&n_rcu_perf_writer_started) >= nrealwriters)
+ atomic_read(&n_rcu_scale_writer_started) >= nrealwriters)
started = true;
if (!done && i >= MIN_MEAS) {
done = true;
sched_set_normal(current, 0);
- pr_alert("%s%s rcu_perf_writer %ld has %d measurements\n",
- perf_type, PERF_FLAG, me, MIN_MEAS);
- if (atomic_inc_return(&n_rcu_perf_writer_finished) >=
+ pr_alert("%s%s rcu_scale_writer %ld has %d measurements\n",
+ scale_type, SCALE_FLAG, me, MIN_MEAS);
+ if (atomic_inc_return(&n_rcu_scale_writer_finished) >=
nrealwriters) {
schedule_timeout_interruptible(10);
rcu_ftrace_dump(DUMP_ALL);
- PERFOUT_STRING("Test complete");
- t_rcu_perf_writer_finished = t;
+ SCALEOUT_STRING("Test complete");
+ t_rcu_scale_writer_finished = t;
if (gp_exp) {
b_rcu_gp_test_finished =
cur_ops->exp_completed() / 2;
@@ -448,30 +448,30 @@ retry:
}
}
if (done && !alldone &&
- atomic_read(&n_rcu_perf_writer_finished) >= nrealwriters)
+ atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters)
alldone = true;
if (started && !alldone && i < MAX_MEAS - 1)
i++;
- rcu_perf_wait_shutdown();
+ rcu_scale_wait_shutdown();
} while (!torture_must_stop());
if (gp_async) {
cur_ops->gp_barrier();
}
writer_n_durations[me] = i_max;
- torture_kthread_stopping("rcu_perf_writer");
+ torture_kthread_stopping("rcu_scale_writer");
return 0;
}
static void
-rcu_perf_print_module_parms(struct rcu_perf_ops *cur_ops, const char *tag)
+rcu_scale_print_module_parms(struct rcu_scale_ops *cur_ops, const char *tag)
{
- pr_alert("%s" PERF_FLAG
+ pr_alert("%s" SCALE_FLAG
"--- %s: nreaders=%d nwriters=%d verbose=%d shutdown=%d\n",
- perf_type, tag, nrealreaders, nrealwriters, verbose, shutdown);
+ scale_type, tag, nrealreaders, nrealwriters, verbose, shutdown);
}
static void
-rcu_perf_cleanup(void)
+rcu_scale_cleanup(void)
{
int i;
int j;
@@ -484,11 +484,11 @@ rcu_perf_cleanup(void)
* during the mid-boot phase, so have to wait till the end.
*/
if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp)
- VERBOSE_PERFOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
+ VERBOSE_SCALEOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
if (rcu_gp_is_normal() && gp_exp)
- VERBOSE_PERFOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
+ VERBOSE_SCALEOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
if (gp_exp && gp_async)
- VERBOSE_PERFOUT_ERRSTRING("No expedited async GPs, so went with async!");
+ VERBOSE_SCALEOUT_ERRSTRING("No expedited async GPs, so went with async!");
if (torture_cleanup_begin())
return;
@@ -499,30 +499,30 @@ rcu_perf_cleanup(void)
if (reader_tasks) {
for (i = 0; i < nrealreaders; i++)
- torture_stop_kthread(rcu_perf_reader,
+ torture_stop_kthread(rcu_scale_reader,
reader_tasks[i]);
kfree(reader_tasks);
}
if (writer_tasks) {
for (i = 0; i < nrealwriters; i++) {
- torture_stop_kthread(rcu_perf_writer,
+ torture_stop_kthread(rcu_scale_writer,
writer_tasks[i]);
if (!writer_n_durations)
continue;
j = writer_n_durations[i];
pr_alert("%s%s writer %d gps: %d\n",
- perf_type, PERF_FLAG, i, j);
+ scale_type, SCALE_FLAG, i, j);
ngps += j;
}
pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n",
- perf_type, PERF_FLAG,
- t_rcu_perf_writer_started, t_rcu_perf_writer_finished,
- t_rcu_perf_writer_finished -
- t_rcu_perf_writer_started,
+ scale_type, SCALE_FLAG,
+ t_rcu_scale_writer_started, t_rcu_scale_writer_finished,
+ t_rcu_scale_writer_finished -
+ t_rcu_scale_writer_started,
ngps,
- rcuperf_seq_diff(b_rcu_gp_test_finished,
- b_rcu_gp_test_started));
+ rcuscale_seq_diff(b_rcu_gp_test_finished,
+ b_rcu_gp_test_started));
for (i = 0; i < nrealwriters; i++) {
if (!writer_durations)
break;
@@ -534,7 +534,7 @@ rcu_perf_cleanup(void)
for (j = 0; j <= writer_n_durations[i]; j++) {
wdp = &wdpp[j];
pr_alert("%s%s %4d writer-duration: %5d %llu\n",
- perf_type, PERF_FLAG,
+ scale_type, SCALE_FLAG,
i, j, *wdp);
if (j % 100 == 0)
schedule_timeout_uninterruptible(1);
@@ -573,22 +573,22 @@ static int compute_real(int n)
}
/*
- * RCU perf shutdown kthread. Just waits to be awakened, then shuts
+ * RCU scalability shutdown kthread. Just waits to be awakened, then shuts
* down system.
*/
static int
-rcu_perf_shutdown(void *arg)
+rcu_scale_shutdown(void *arg)
{
wait_event(shutdown_wq,
- atomic_read(&n_rcu_perf_writer_finished) >= nrealwriters);
+ atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters);
smp_mb(); /* Wake before output. */
- rcu_perf_cleanup();
+ rcu_scale_cleanup();
kernel_power_off();
return -EINVAL;
}
/*
- * kfree_rcu() performance tests: Start a kfree_rcu() loop on all CPUs for number
+ * kfree_rcu() scalability tests: Start a kfree_rcu() loop on all CPUs for number
* of iterations and measure total time and number of GP for all iterations to complete.
*/
@@ -598,8 +598,8 @@ torture_param(int, kfree_loops, 10, "Number of loops doing kfree_alloc_num alloc
static struct task_struct **kfree_reader_tasks;
static int kfree_nrealthreads;
-static atomic_t n_kfree_perf_thread_started;
-static atomic_t n_kfree_perf_thread_ended;
+static atomic_t n_kfree_scale_thread_started;
+static atomic_t n_kfree_scale_thread_ended;
struct kfree_obj {
char kfree_obj[8];
@@ -607,7 +607,7 @@ struct kfree_obj {
};
static int
-kfree_perf_thread(void *arg)
+kfree_scale_thread(void *arg)
{
int i, loop = 0;
long me = (long)arg;
@@ -615,13 +615,13 @@ kfree_perf_thread(void *arg)
u64 start_time, end_time;
long long mem_begin, mem_during = 0;
- VERBOSE_PERFOUT_STRING("kfree_perf_thread task started");
+ VERBOSE_SCALEOUT_STRING("kfree_scale_thread task started");
set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
set_user_nice(current, MAX_NICE);
start_time = ktime_get_mono_fast_ns();
- if (atomic_inc_return(&n_kfree_perf_thread_started) >= kfree_nrealthreads) {
+ if (atomic_inc_return(&n_kfree_scale_thread_started) >= kfree_nrealthreads) {
if (gp_exp)
b_rcu_gp_test_started = cur_ops->exp_completed() / 2;
else
@@ -646,7 +646,7 @@ kfree_perf_thread(void *arg)
cond_resched();
} while (!torture_must_stop() && ++loop < kfree_loops);
- if (atomic_inc_return(&n_kfree_perf_thread_ended) >= kfree_nrealthreads) {
+ if (atomic_inc_return(&n_kfree_scale_thread_ended) >= kfree_nrealthreads) {
end_time = ktime_get_mono_fast_ns();
if (gp_exp)
@@ -656,7 +656,7 @@ kfree_perf_thread(void *arg)
pr_alert("Total time taken by all kfree'ers: %llu ns, loops: %d, batches: %ld, memory footprint: %lldMB\n",
(unsigned long long)(end_time - start_time), kfree_loops,
- rcuperf_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started),
+ rcuscale_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started),
(mem_begin - mem_during) >> (20 - PAGE_SHIFT));
if (shutdown) {
@@ -665,12 +665,12 @@ kfree_perf_thread(void *arg)
}
}
- torture_kthread_stopping("kfree_perf_thread");
+ torture_kthread_stopping("kfree_scale_thread");
return 0;
}
static void
-kfree_perf_cleanup(void)
+kfree_scale_cleanup(void)
{
int i;
@@ -679,7 +679,7 @@ kfree_perf_cleanup(void)
if (kfree_reader_tasks) {
for (i = 0; i < kfree_nrealthreads; i++)
- torture_stop_kthread(kfree_perf_thread,
+ torture_stop_kthread(kfree_scale_thread,
kfree_reader_tasks[i]);
kfree(kfree_reader_tasks);
}
@@ -691,20 +691,20 @@ kfree_perf_cleanup(void)
* shutdown kthread. Just waits to be awakened, then shuts down system.
*/
static int
-kfree_perf_shutdown(void *arg)
+kfree_scale_shutdown(void *arg)
{
wait_event(shutdown_wq,
- atomic_read(&n_kfree_perf_thread_ended) >= kfree_nrealthreads);
+ atomic_read(&n_kfree_scale_thread_ended) >= kfree_nrealthreads);
smp_mb(); /* Wake before output. */
- kfree_perf_cleanup();
+ kfree_scale_cleanup();
kernel_power_off();
return -EINVAL;
}
static int __init
-kfree_perf_init(void)
+kfree_scale_init(void)
{
long i;
int firsterr = 0;
@@ -713,7 +713,7 @@ kfree_perf_init(void)
/* Start up the kthreads. */
if (shutdown) {
init_waitqueue_head(&shutdown_wq);
- firsterr = torture_create_kthread(kfree_perf_shutdown, NULL,
+ firsterr = torture_create_kthread(kfree_scale_shutdown, NULL,
shutdown_task);
if (firsterr)
goto unwind;
@@ -730,13 +730,13 @@ kfree_perf_init(void)
}
for (i = 0; i < kfree_nrealthreads; i++) {
- firsterr = torture_create_kthread(kfree_perf_thread, (void *)i,
+ firsterr = torture_create_kthread(kfree_scale_thread, (void *)i,
kfree_reader_tasks[i]);
if (firsterr)
goto unwind;
}
- while (atomic_read(&n_kfree_perf_thread_started) < kfree_nrealthreads)
+ while (atomic_read(&n_kfree_scale_thread_started) < kfree_nrealthreads)
schedule_timeout_uninterruptible(1);
torture_init_end();
@@ -744,35 +744,35 @@ kfree_perf_init(void)
unwind:
torture_init_end();
- kfree_perf_cleanup();
+ kfree_scale_cleanup();
return firsterr;
}
static int __init
-rcu_perf_init(void)
+rcu_scale_init(void)
{
long i;
int firsterr = 0;
- static struct rcu_perf_ops *perf_ops[] = {
+ static struct rcu_scale_ops *scale_ops[] = {
&rcu_ops, &srcu_ops, &srcud_ops, &tasks_ops,
};
- if (!torture_init_begin(perf_type, verbose))
+ if (!torture_init_begin(scale_type, verbose))
return -EBUSY;
- /* Process args and tell the world that the perf'er is on the job. */
- for (i = 0; i < ARRAY_SIZE(perf_ops); i++) {
- cur_ops = perf_ops[i];
- if (strcmp(perf_type, cur_ops->name) == 0)
+ /* Process args and announce that the scalability'er is on the job. */
+ for (i = 0; i < ARRAY_SIZE(scale_ops); i++) {
+ cur_ops = scale_ops[i];
+ if (strcmp(scale_type, cur_ops->name) == 0)
break;
}
- if (i == ARRAY_SIZE(perf_ops)) {
- pr_alert("rcu-perf: invalid perf type: \"%s\"\n", perf_type);
- pr_alert("rcu-perf types:");
- for (i = 0; i < ARRAY_SIZE(perf_ops); i++)
- pr_cont(" %s", perf_ops[i]->name);
+ if (i == ARRAY_SIZE(scale_ops)) {
+ pr_alert("rcu-scale: invalid scale type: \"%s\"\n", scale_type);
+ pr_alert("rcu-scale types:");
+ for (i = 0; i < ARRAY_SIZE(scale_ops); i++)
+ pr_cont(" %s", scale_ops[i]->name);
pr_cont("\n");
- WARN_ON(!IS_MODULE(CONFIG_RCU_PERF_TEST));
+ WARN_ON(!IS_MODULE(CONFIG_RCU_SCALE_TEST));
firsterr = -EINVAL;
cur_ops = NULL;
goto unwind;
@@ -781,20 +781,20 @@ rcu_perf_init(void)
cur_ops->init();
if (kfree_rcu_test)
- return kfree_perf_init();
+ return kfree_scale_init();
nrealwriters = compute_real(nwriters);
nrealreaders = compute_real(nreaders);
- atomic_set(&n_rcu_perf_reader_started, 0);
- atomic_set(&n_rcu_perf_writer_started, 0);
- atomic_set(&n_rcu_perf_writer_finished, 0);
- rcu_perf_print_module_parms(cur_ops, "Start of test");
+ atomic_set(&n_rcu_scale_reader_started, 0);
+ atomic_set(&n_rcu_scale_writer_started, 0);
+ atomic_set(&n_rcu_scale_writer_finished, 0);
+ rcu_scale_print_module_parms(cur_ops, "Start of test");
/* Start up the kthreads. */
if (shutdown) {
init_waitqueue_head(&shutdown_wq);
- firsterr = torture_create_kthread(rcu_perf_shutdown, NULL,
+ firsterr = torture_create_kthread(rcu_scale_shutdown, NULL,
shutdown_task);
if (firsterr)
goto unwind;
@@ -803,17 +803,17 @@ rcu_perf_init(void)
reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
GFP_KERNEL);
if (reader_tasks == NULL) {
- VERBOSE_PERFOUT_ERRSTRING("out of memory");
+ VERBOSE_SCALEOUT_ERRSTRING("out of memory");
firsterr = -ENOMEM;
goto unwind;
}
for (i = 0; i < nrealreaders; i++) {
- firsterr = torture_create_kthread(rcu_perf_reader, (void *)i,
+ firsterr = torture_create_kthread(rcu_scale_reader, (void *)i,
reader_tasks[i]);
if (firsterr)
goto unwind;
}
- while (atomic_read(&n_rcu_perf_reader_started) < nrealreaders)
+ while (atomic_read(&n_rcu_scale_reader_started) < nrealreaders)
schedule_timeout_uninterruptible(1);
writer_tasks = kcalloc(nrealwriters, sizeof(reader_tasks[0]),
GFP_KERNEL);
@@ -823,7 +823,7 @@ rcu_perf_init(void)
kcalloc(nrealwriters, sizeof(*writer_n_durations),
GFP_KERNEL);
if (!writer_tasks || !writer_durations || !writer_n_durations) {
- VERBOSE_PERFOUT_ERRSTRING("out of memory");
+ VERBOSE_SCALEOUT_ERRSTRING("out of memory");
firsterr = -ENOMEM;
goto unwind;
}
@@ -835,7 +835,7 @@ rcu_perf_init(void)
firsterr = -ENOMEM;
goto unwind;
}
- firsterr = torture_create_kthread(rcu_perf_writer, (void *)i,
+ firsterr = torture_create_kthread(rcu_scale_writer, (void *)i,
writer_tasks[i]);
if (firsterr)
goto unwind;
@@ -845,9 +845,9 @@ rcu_perf_init(void)
unwind:
torture_init_end();
- rcu_perf_cleanup();
+ rcu_scale_cleanup();
return firsterr;
}
-module_init(rcu_perf_init);
-module_exit(rcu_perf_cleanup);
+module_init(rcu_scale_init);
+module_exit(rcu_scale_cleanup);
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index f453bf8d2f1e..916ea4f66e4b 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -52,19 +52,6 @@
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
-#ifndef data_race
-#define data_race(expr) \
- ({ \
- expr; \
- })
-#endif
-#ifndef ASSERT_EXCLUSIVE_WRITER
-#define ASSERT_EXCLUSIVE_WRITER(var) do { } while (0)
-#endif
-#ifndef ASSERT_EXCLUSIVE_ACCESS
-#define ASSERT_EXCLUSIVE_ACCESS(var) do { } while (0)
-#endif
-
/* Bits for ->extendables field, extendables param, and related definitions. */
#define RCUTORTURE_RDR_SHIFT 8 /* Put SRCU index in upper bits. */
#define RCUTORTURE_RDR_MASK ((1 << RCUTORTURE_RDR_SHIFT) - 1)
@@ -100,6 +87,7 @@ torture_param(bool, gp_normal, false,
"Use normal (non-expedited) GP wait primitives");
torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
+torture_param(int, leakpointer, 0, "Leak pointer dereferences from readers");
torture_param(int, n_barrier_cbs, 0,
"# of callbacks/kthreads for barrier testing");
torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
@@ -185,6 +173,7 @@ static long n_barrier_successes; /* did rcu_barrier test succeed? */
static unsigned long n_read_exits;
static struct list_head rcu_torture_removed;
static unsigned long shutdown_jiffies;
+static unsigned long start_gp_seq;
static int rcu_torture_writer_state;
#define RTWS_FIXED_DELAY 0
@@ -1413,6 +1402,9 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp)
preempt_enable();
rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
+ // This next splat is expected behavior if leakpointer, especially
+ // for CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels.
+ WARN_ON_ONCE(leakpointer && READ_ONCE(p->rtort_pipe_count) > 1);
/* If error or close call, record the sequence of reader protections. */
if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
@@ -1808,6 +1800,7 @@ struct rcu_fwd {
unsigned long rcu_launder_gp_seq_start;
};
+static DEFINE_MUTEX(rcu_fwd_mutex);
static struct rcu_fwd *rcu_fwds;
static bool rcu_fwd_emergency_stop;
@@ -2074,8 +2067,14 @@ static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp)
static int rcutorture_oom_notify(struct notifier_block *self,
unsigned long notused, void *nfreed)
{
- struct rcu_fwd *rfp = rcu_fwds;
+ struct rcu_fwd *rfp;
+ mutex_lock(&rcu_fwd_mutex);
+ rfp = rcu_fwds;
+ if (!rfp) {
+ mutex_unlock(&rcu_fwd_mutex);
+ return NOTIFY_OK;
+ }
WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
__func__);
rcu_torture_fwd_cb_hist(rfp);
@@ -2093,6 +2092,7 @@ static int rcutorture_oom_notify(struct notifier_block *self,
smp_mb(); /* Frees before return to avoid redoing OOM. */
(*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
pr_info("%s returning after OOM processing.\n", __func__);
+ mutex_unlock(&rcu_fwd_mutex);
return NOTIFY_OK;
}
@@ -2114,13 +2114,11 @@ static int rcu_torture_fwd_prog(void *args)
do {
schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
WRITE_ONCE(rcu_fwd_emergency_stop, false);
- register_oom_notifier(&rcutorture_oom_nb);
if (!IS_ENABLED(CONFIG_TINY_RCU) ||
rcu_inkernel_boot_has_ended())
rcu_torture_fwd_prog_nr(rfp, &tested, &tested_tries);
if (rcu_inkernel_boot_has_ended())
rcu_torture_fwd_prog_cr(rfp);
- unregister_oom_notifier(&rcutorture_oom_nb);
/* Avoid slow periods, better to test when busy. */
stutter_wait("rcu_torture_fwd_prog");
@@ -2160,9 +2158,26 @@ static int __init rcu_torture_fwd_prog_init(void)
return -ENOMEM;
spin_lock_init(&rfp->rcu_fwd_lock);
rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;
+ mutex_lock(&rcu_fwd_mutex);
+ rcu_fwds = rfp;
+ mutex_unlock(&rcu_fwd_mutex);
+ register_oom_notifier(&rcutorture_oom_nb);
return torture_create_kthread(rcu_torture_fwd_prog, rfp, fwd_prog_task);
}
+static void rcu_torture_fwd_prog_cleanup(void)
+{
+ struct rcu_fwd *rfp;
+
+ torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
+ rfp = rcu_fwds;
+ mutex_lock(&rcu_fwd_mutex);
+ rcu_fwds = NULL;
+ mutex_unlock(&rcu_fwd_mutex);
+ unregister_oom_notifier(&rcutorture_oom_nb);
+ kfree(rfp);
+}
+
/* Callback function for RCU barrier testing. */
static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
{
@@ -2460,7 +2475,7 @@ rcu_torture_cleanup(void)
show_rcu_gp_kthreads();
rcu_torture_read_exit_cleanup();
rcu_torture_barrier_cleanup();
- torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
+ rcu_torture_fwd_prog_cleanup();
torture_stop_kthread(rcu_torture_stall, stall_task);
torture_stop_kthread(rcu_torture_writer, writer_task);
@@ -2482,8 +2497,9 @@ rcu_torture_cleanup(void)
rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
- pr_alert("%s: End-test grace-period state: g%lu f%#x\n",
- cur_ops->name, gp_seq, flags);
+ pr_alert("%s: End-test grace-period state: g%ld f%#x total-gps=%ld\n",
+ cur_ops->name, (long)gp_seq, flags,
+ rcutorture_seq_diff(gp_seq, start_gp_seq));
torture_stop_kthread(rcu_torture_stats, stats_task);
torture_stop_kthread(rcu_torture_fqs, fqs_task);
if (rcu_torture_can_boost())
@@ -2607,6 +2623,8 @@ rcu_torture_init(void)
long i;
int cpu;
int firsterr = 0;
+ int flags = 0;
+ unsigned long gp_seq = 0;
static struct rcu_torture_ops *torture_ops[] = {
&rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
&busted_srcud_ops, &tasks_ops, &tasks_rude_ops,
@@ -2649,6 +2667,11 @@ rcu_torture_init(void)
nrealreaders = 1;
}
rcu_torture_print_module_parms(cur_ops, "Start of test");
+ rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
+ srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
+ start_gp_seq = gp_seq;
+ pr_alert("%s: Start-test grace-period state: g%ld f%#x\n",
+ cur_ops->name, (long)gp_seq, flags);
/* Set up the freelist. */
diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
index d9291f883b54..952595c678b3 100644
--- a/kernel/rcu/refscale.c
+++ b/kernel/rcu/refscale.c
@@ -546,9 +546,11 @@ static int main_func(void *arg)
// Print the average of all experiments
SCALEOUT("END OF TEST. Calculating average duration per loop (nanoseconds)...\n");
- buf[0] = 0;
- strcat(buf, "\n");
- strcat(buf, "Runs\tTime(ns)\n");
+ if (!errexit) {
+ buf[0] = 0;
+ strcat(buf, "\n");
+ strcat(buf, "Runs\tTime(ns)\n");
+ }
for (exp = 0; exp < nruns; exp++) {
u64 avg;
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index c100acf332ed..c13348ee80a5 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -29,19 +29,6 @@
#include "rcu.h"
#include "rcu_segcblist.h"
-#ifndef data_race
-#define data_race(expr) \
- ({ \
- expr; \
- })
-#endif
-#ifndef ASSERT_EXCLUSIVE_WRITER
-#define ASSERT_EXCLUSIVE_WRITER(var) do { } while (0)
-#endif
-#ifndef ASSERT_EXCLUSIVE_ACCESS
-#define ASSERT_EXCLUSIVE_ACCESS(var) do { } while (0)
-#endif
-
/* Holdoff in nanoseconds for auto-expediting. */
#define DEFAULT_SRCU_EXP_HOLDOFF (25 * 1000)
static ulong exp_holdoff = DEFAULT_SRCU_EXP_HOLDOFF;
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 03c54c3478b7..06895ef85d69 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -70,19 +70,6 @@
#endif
#define MODULE_PARAM_PREFIX "rcutree."
-#ifndef data_race
-#define data_race(expr) \
- ({ \
- expr; \
- })
-#endif
-#ifndef ASSERT_EXCLUSIVE_WRITER
-#define ASSERT_EXCLUSIVE_WRITER(var) do { } while (0)
-#endif
-#ifndef ASSERT_EXCLUSIVE_ACCESS
-#define ASSERT_EXCLUSIVE_ACCESS(var) do { } while (0)
-#endif
-
/* Data structures. */
/*
@@ -178,6 +165,12 @@ module_param(gp_init_delay, int, 0444);
static int gp_cleanup_delay;
module_param(gp_cleanup_delay, int, 0444);
+// Add delay to rcu_read_unlock() for strict grace periods.
+static int rcu_unlock_delay;
+#ifdef CONFIG_RCU_STRICT_GRACE_PERIOD
+module_param(rcu_unlock_delay, int, 0444);
+#endif
+
/*
* This rcu parameter is runtime-read-only. It reflects
* a minimum allowed number of objects which can be cached
@@ -468,24 +461,25 @@ static int rcu_is_cpu_rrupt_from_idle(void)
return __this_cpu_read(rcu_data.dynticks_nesting) == 0;
}
-#define DEFAULT_RCU_BLIMIT 10 /* Maximum callbacks per rcu_do_batch ... */
-#define DEFAULT_MAX_RCU_BLIMIT 10000 /* ... even during callback flood. */
+#define DEFAULT_RCU_BLIMIT (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) ? 1000 : 10)
+ // Maximum callbacks per rcu_do_batch ...
+#define DEFAULT_MAX_RCU_BLIMIT 10000 // ... even during callback flood.
static long blimit = DEFAULT_RCU_BLIMIT;
-#define DEFAULT_RCU_QHIMARK 10000 /* If this many pending, ignore blimit. */
+#define DEFAULT_RCU_QHIMARK 10000 // If this many pending, ignore blimit.
static long qhimark = DEFAULT_RCU_QHIMARK;
-#define DEFAULT_RCU_QLOMARK 100 /* Once only this many pending, use blimit. */
+#define DEFAULT_RCU_QLOMARK 100 // Once only this many pending, use blimit.
static long qlowmark = DEFAULT_RCU_QLOMARK;
#define DEFAULT_RCU_QOVLD_MULT 2
#define DEFAULT_RCU_QOVLD (DEFAULT_RCU_QOVLD_MULT * DEFAULT_RCU_QHIMARK)
-static long qovld = DEFAULT_RCU_QOVLD; /* If this many pending, hammer QS. */
-static long qovld_calc = -1; /* No pre-initialization lock acquisitions! */
+static long qovld = DEFAULT_RCU_QOVLD; // If this many pending, hammer QS.
+static long qovld_calc = -1; // No pre-initialization lock acquisitions!
module_param(blimit, long, 0444);
module_param(qhimark, long, 0444);
module_param(qlowmark, long, 0444);
module_param(qovld, long, 0444);
-static ulong jiffies_till_first_fqs = ULONG_MAX;
+static ulong jiffies_till_first_fqs = IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) ? 0 : ULONG_MAX;
static ulong jiffies_till_next_fqs = ULONG_MAX;
static bool rcu_kick_kthreads;
static int rcu_divisor = 7;
@@ -1092,11 +1086,6 @@ static void rcu_disable_urgency_upon_qs(struct rcu_data *rdp)
}
}
-noinstr bool __rcu_is_watching(void)
-{
- return !rcu_dynticks_curr_cpu_in_eqs();
-}
-
/**
* rcu_is_watching - see if RCU thinks that the current CPU is not idle
*
@@ -1229,13 +1218,28 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
return 1;
}
- /* If waiting too long on an offline CPU, complain. */
- if (!(rdp->grpmask & rcu_rnp_online_cpus(rnp)) &&
- time_after(jiffies, rcu_state.gp_start + HZ)) {
+ /*
+ * Complain if a CPU that is considered to be offline from RCU's
+ * perspective has not yet reported a quiescent state. After all,
+ * the offline CPU should have reported a quiescent state during
+ * the CPU-offline process, or, failing that, by rcu_gp_init()
+ * if it ran concurrently with either the CPU going offline or the
+ * last task on a leaf rcu_node structure exiting its RCU read-side
+ * critical section while all CPUs corresponding to that structure
+ * are offline. This added warning detects bugs in any of these
+ * code paths.
+ *
+ * The rcu_node structure's ->lock is held here, which excludes
+ * the relevant portions the CPU-hotplug code, the grace-period
+ * initialization code, and the rcu_read_unlock() code paths.
+ *
+ * For more detail, please refer to the "Hotplug CPU" section
+ * of RCU's Requirements documentation.
+ */
+ if (WARN_ON_ONCE(!(rdp->grpmask & rcu_rnp_online_cpus(rnp)))) {
bool onl;
struct rcu_node *rnp1;
- WARN_ON(1); /* Offline CPUs are supposed to report QS! */
pr_info("%s: grp: %d-%d level: %d ->gp_seq %ld ->completedqs %ld\n",
__func__, rnp->grplo, rnp->grphi, rnp->level,
(long)rnp->gp_seq, (long)rnp->completedqs);
@@ -1498,9 +1502,10 @@ static bool rcu_accelerate_cbs(struct rcu_node *rnp, struct rcu_data *rdp)
/* Trace depending on how much we were able to accelerate. */
if (rcu_segcblist_restempty(&rdp->cblist, RCU_WAIT_TAIL))
- trace_rcu_grace_period(rcu_state.name, rdp->gp_seq, TPS("AccWaitCB"));
+ trace_rcu_grace_period(rcu_state.name, gp_seq_req, TPS("AccWaitCB"));
else
- trace_rcu_grace_period(rcu_state.name, rdp->gp_seq, TPS("AccReadyCB"));
+ trace_rcu_grace_period(rcu_state.name, gp_seq_req, TPS("AccReadyCB"));
+
return ret;
}
@@ -1576,6 +1581,19 @@ static void __maybe_unused rcu_advance_cbs_nowake(struct rcu_node *rnp,
}
/*
+ * In CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels, attempt to generate a
+ * quiescent state. This is intended to be invoked when the CPU notices
+ * a new grace period.
+ */
+static void rcu_strict_gp_check_qs(void)
+{
+ if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)) {
+ rcu_read_lock();
+ rcu_read_unlock();
+ }
+}
+
+/*
* Update CPU-local rcu_data state to record the beginnings and ends of
* grace periods. The caller must hold the ->lock of the leaf rcu_node
* structure corresponding to the current CPU, and must have irqs disabled.
@@ -1645,6 +1663,7 @@ static void note_gp_changes(struct rcu_data *rdp)
}
needwake = __note_gp_changes(rnp, rdp);
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
+ rcu_strict_gp_check_qs();
if (needwake)
rcu_gp_kthread_wake();
}
@@ -1683,6 +1702,15 @@ static void rcu_gp_torture_wait(void)
}
/*
+ * Handler for on_each_cpu() to invoke the target CPU's RCU core
+ * processing.
+ */
+static void rcu_strict_gp_boundary(void *unused)
+{
+ invoke_rcu_core();
+}
+
+/*
* Initialize a new grace period. Return false if no grace period required.
*/
static bool rcu_gp_init(void)
@@ -1720,10 +1748,13 @@ static bool rcu_gp_init(void)
raw_spin_unlock_irq_rcu_node(rnp);
/*
- * Apply per-leaf buffered online and offline operations to the
- * rcu_node tree. Note that this new grace period need not wait
- * for subsequent online CPUs, and that quiescent-state forcing
- * will handle subsequent offline CPUs.
+ * Apply per-leaf buffered online and offline operations to
+ * the rcu_node tree. Note that this new grace period need not
+ * wait for subsequent online CPUs, and that RCU hooks in the CPU
+ * offlining path, when combined with checks in this function,
+ * will handle CPUs that are currently going offline or that will
+ * go offline later. Please also refer to "Hotplug CPU" section
+ * of RCU's Requirements documentation.
*/
rcu_state.gp_state = RCU_GP_ONOFF;
rcu_for_each_leaf_node(rnp) {
@@ -1810,6 +1841,10 @@ static bool rcu_gp_init(void)
WRITE_ONCE(rcu_state.gp_activity, jiffies);
}
+ // If strict, make all CPUs aware of new grace period.
+ if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD))
+ on_each_cpu(rcu_strict_gp_boundary, NULL, 0);
+
return true;
}
@@ -1898,7 +1933,7 @@ static void rcu_gp_fqs_loop(void)
break;
/* If time for quiescent-state forcing, do it. */
if (!time_after(rcu_state.jiffies_force_qs, jiffies) ||
- (gf & RCU_GP_FLAG_FQS)) {
+ (gf & (RCU_GP_FLAG_FQS | RCU_GP_FLAG_OVLD))) {
trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq,
TPS("fqsstart"));
rcu_gp_fqs(first_gp_fqs);
@@ -2026,6 +2061,10 @@ static void rcu_gp_cleanup(void)
rcu_state.gp_flags & RCU_GP_FLAG_INIT);
}
raw_spin_unlock_irq_rcu_node(rnp);
+
+ // If strict, make all CPUs aware of the end of the old grace period.
+ if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD))
+ on_each_cpu(rcu_strict_gp_boundary, NULL, 0);
}
/*
@@ -2204,7 +2243,7 @@ rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned long flags)
* structure. This must be called from the specified CPU.
*/
static void
-rcu_report_qs_rdp(int cpu, struct rcu_data *rdp)
+rcu_report_qs_rdp(struct rcu_data *rdp)
{
unsigned long flags;
unsigned long mask;
@@ -2213,6 +2252,7 @@ rcu_report_qs_rdp(int cpu, struct rcu_data *rdp)
rcu_segcblist_is_offloaded(&rdp->cblist);
struct rcu_node *rnp;
+ WARN_ON_ONCE(rdp->cpu != smp_processor_id());
rnp = rdp->mynode;
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (rdp->cpu_no_qs.b.norm || rdp->gp_seq != rnp->gp_seq ||
@@ -2229,8 +2269,7 @@ rcu_report_qs_rdp(int cpu, struct rcu_data *rdp)
return;
}
mask = rdp->grpmask;
- if (rdp->cpu == smp_processor_id())
- rdp->core_needs_qs = false;
+ rdp->core_needs_qs = false;
if ((rnp->qsmask & mask) == 0) {
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
} else {
@@ -2279,7 +2318,7 @@ rcu_check_quiescent_state(struct rcu_data *rdp)
* Tell RCU we are done (but rcu_report_qs_rdp() will be the
* judge of that).
*/
- rcu_report_qs_rdp(rdp->cpu, rdp);
+ rcu_report_qs_rdp(rdp);
}
/*
@@ -2376,6 +2415,7 @@ int rcutree_dead_cpu(unsigned int cpu)
*/
static void rcu_do_batch(struct rcu_data *rdp)
{
+ int div;
unsigned long flags;
const bool offloaded = IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
rcu_segcblist_is_offloaded(&rdp->cblist);
@@ -2404,9 +2444,15 @@ static void rcu_do_batch(struct rcu_data *rdp)
rcu_nocb_lock(rdp);
WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
pending = rcu_segcblist_n_cbs(&rdp->cblist);
- bl = max(rdp->blimit, pending >> rcu_divisor);
- if (unlikely(bl > 100))
- tlimit = local_clock() + rcu_resched_ns;
+ div = READ_ONCE(rcu_divisor);
+ div = div < 0 ? 7 : div > sizeof(long) * 8 - 2 ? sizeof(long) * 8 - 2 : div;
+ bl = max(rdp->blimit, pending >> div);
+ if (unlikely(bl > 100)) {
+ long rrn = READ_ONCE(rcu_resched_ns);
+
+ rrn = rrn < NSEC_PER_MSEC ? NSEC_PER_MSEC : rrn > NSEC_PER_SEC ? NSEC_PER_SEC : rrn;
+ tlimit = local_clock() + rrn;
+ }
trace_rcu_batch_start(rcu_state.name,
rcu_segcblist_n_cbs(&rdp->cblist), bl);
rcu_segcblist_extract_done_cbs(&rdp->cblist, &rcl);
@@ -2547,8 +2593,7 @@ static void force_qs_rnp(int (*f)(struct rcu_data *rdp))
raw_spin_lock_irqsave_rcu_node(rnp, flags);
rcu_state.cbovldnext |= !!rnp->cbovldmask;
if (rnp->qsmask == 0) {
- if (!IS_ENABLED(CONFIG_PREEMPT_RCU) ||
- rcu_preempt_blocked_readers_cgp(rnp)) {
+ if (rcu_preempt_blocked_readers_cgp(rnp)) {
/*
* No point in scanning bits because they
* are all zero. But we might need to
@@ -2616,6 +2661,14 @@ void rcu_force_quiescent_state(void)
}
EXPORT_SYMBOL_GPL(rcu_force_quiescent_state);
+// Workqueue handler for an RCU reader for kernels enforcing struct RCU
+// grace periods.
+static void strict_work_handler(struct work_struct *work)
+{
+ rcu_read_lock();
+ rcu_read_unlock();
+}
+
/* Perform RCU core processing work for the current CPU. */
static __latent_entropy void rcu_core(void)
{
@@ -2660,6 +2713,10 @@ static __latent_entropy void rcu_core(void)
/* Do any needed deferred wakeups of rcuo kthreads. */
do_nocb_deferred_wakeup(rdp);
trace_rcu_utilization(TPS("End RCU core"));
+
+ // If strict GPs, schedule an RCU reader in a clean environment.
+ if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD))
+ queue_work_on(rdp->cpu, rcu_gp_wq, &rdp->strict_work);
}
static void rcu_core_si(struct softirq_action *h)
@@ -3443,7 +3500,7 @@ kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
unsigned long count = 0;
/* Snapshot count of all CPUs */
- for_each_online_cpu(cpu) {
+ for_each_possible_cpu(cpu) {
struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
count += READ_ONCE(krcp->count);
@@ -3458,7 +3515,7 @@ kfree_rcu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
int cpu, freed = 0;
unsigned long flags;
- for_each_online_cpu(cpu) {
+ for_each_possible_cpu(cpu) {
int count;
struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
@@ -3491,7 +3548,7 @@ void __init kfree_rcu_scheduler_running(void)
int cpu;
unsigned long flags;
- for_each_online_cpu(cpu) {
+ for_each_possible_cpu(cpu) {
struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
raw_spin_lock_irqsave(&krcp->lock, flags);
@@ -3855,6 +3912,7 @@ rcu_boot_init_percpu_data(int cpu)
/* Set up local state, ensuring consistent view of global state. */
rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu);
+ INIT_WORK(&rdp->strict_work, strict_work_handler);
WARN_ON_ONCE(rdp->dynticks_nesting != 1);
WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp)));
rdp->rcu_ofl_gp_seq = rcu_state.gp_seq;
@@ -3973,8 +4031,6 @@ int rcutree_offline_cpu(unsigned int cpu)
return 0;
}
-static DEFINE_PER_CPU(int, rcu_cpu_started);
-
/*
* Mark the specified CPU as being online so that subsequent grace periods
* (both expedited and normal) will wait on it. Note that this means that
@@ -3994,12 +4050,11 @@ void rcu_cpu_starting(unsigned int cpu)
struct rcu_node *rnp;
bool newcpu;
- if (per_cpu(rcu_cpu_started, cpu))
+ rdp = per_cpu_ptr(&rcu_data, cpu);
+ if (rdp->cpu_started)
return;
+ rdp->cpu_started = true;
- per_cpu(rcu_cpu_started, cpu) = 1;
-
- rdp = per_cpu_ptr(&rcu_data, cpu);
rnp = rdp->mynode;
mask = rdp->grpmask;
raw_spin_lock_irqsave_rcu_node(rnp, flags);
@@ -4059,7 +4114,7 @@ void rcu_report_dead(unsigned int cpu)
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
raw_spin_unlock(&rcu_state.ofl_lock);
- per_cpu(rcu_cpu_started, cpu) = 0;
+ rdp->cpu_started = false;
}
/*
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index c96ae351688b..e4f66b8f7c47 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -156,6 +156,7 @@ struct rcu_data {
bool beenonline; /* CPU online at least once. */
bool gpwrap; /* Possible ->gp_seq wrap. */
bool exp_deferred_qs; /* This CPU awaiting a deferred QS? */
+ bool cpu_started; /* RCU watching this onlining CPU. */
struct rcu_node *mynode; /* This CPU's leaf of hierarchy */
unsigned long grpmask; /* Mask to apply to leaf qsmask. */
unsigned long ticks_this_gp; /* The number of scheduling-clock */
@@ -164,6 +165,7 @@ struct rcu_data {
/* period it is aware of. */
struct irq_work defer_qs_iw; /* Obtain later scheduler attention. */
bool defer_qs_iw_pending; /* Scheduler attention pending? */
+ struct work_struct strict_work; /* Schedule readers for strict GPs. */
/* 2) batch handling */
struct rcu_segcblist cblist; /* Segmented callback list, with */
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index 1888c0eb1216..8760b6ead770 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -732,11 +732,9 @@ static void rcu_exp_need_qs(void)
/* Invoked on each online non-idle CPU for expedited quiescent state. */
static void rcu_exp_handler(void *unused)
{
- struct rcu_data *rdp;
- struct rcu_node *rnp;
+ struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
+ struct rcu_node *rnp = rdp->mynode;
- rdp = this_cpu_ptr(&rcu_data);
- rnp = rdp->mynode;
if (!(READ_ONCE(rnp->expmask) & rdp->grpmask) ||
__this_cpu_read(rcu_data.cpu_no_qs.b.exp))
return;
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 982fc5be5269..fd8a52e9a887 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -36,6 +36,8 @@ static void __init rcu_bootup_announce_oddness(void)
pr_info("\tRCU dyntick-idle grace-period acceleration is enabled.\n");
if (IS_ENABLED(CONFIG_PROVE_RCU))
pr_info("\tRCU lockdep checking is enabled.\n");
+ if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD))
+ pr_info("\tRCU strict (and thus non-scalable) grace periods enabled.\n");
if (RCU_NUM_LVLS >= 4)
pr_info("\tFour(or more)-level hierarchy is enabled.\n");
if (RCU_FANOUT_LEAF != 16)
@@ -374,6 +376,8 @@ void __rcu_read_lock(void)
rcu_preempt_read_enter();
if (IS_ENABLED(CONFIG_PROVE_LOCKING))
WARN_ON_ONCE(rcu_preempt_depth() > RCU_NEST_PMAX);
+ if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) && rcu_state.gp_kthread)
+ WRITE_ONCE(current->rcu_read_unlock_special.b.need_qs, true);
barrier(); /* critical section after entry code. */
}
EXPORT_SYMBOL_GPL(__rcu_read_lock);
@@ -455,8 +459,14 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags)
return;
}
t->rcu_read_unlock_special.s = 0;
- if (special.b.need_qs)
- rcu_qs();
+ if (special.b.need_qs) {
+ if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)) {
+ rcu_report_qs_rdp(rdp);
+ udelay(rcu_unlock_delay);
+ } else {
+ rcu_qs();
+ }
+ }
/*
* Respond to a request by an expedited grace period for a
@@ -769,6 +779,24 @@ dump_blkd_tasks(struct rcu_node *rnp, int ncheck)
#else /* #ifdef CONFIG_PREEMPT_RCU */
/*
+ * If strict grace periods are enabled, and if the calling
+ * __rcu_read_unlock() marks the beginning of a quiescent state, immediately
+ * report that quiescent state and, if requested, spin for a bit.
+ */
+void rcu_read_unlock_strict(void)
+{
+ struct rcu_data *rdp;
+
+ if (!IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) ||
+ irqs_disabled() || preempt_count() || !rcu_state.gp_kthread)
+ return;
+ rdp = this_cpu_ptr(&rcu_data);
+ rcu_report_qs_rdp(rdp);
+ udelay(rcu_unlock_delay);
+}
+EXPORT_SYMBOL_GPL(rcu_read_unlock_strict);
+
+/*
* Tell them what RCU they are running.
*/
static void __init rcu_bootup_announce(void)
@@ -1926,6 +1954,7 @@ static void nocb_gp_wait(struct rcu_data *my_rdp)
* nearest grace period (if any) to wait for next. The CB kthreads
* and the global grace-period kthread are awakened if needed.
*/
+ WARN_ON_ONCE(my_rdp->nocb_gp_rdp != my_rdp);
for (rdp = my_rdp; rdp; rdp = rdp->nocb_next_cb_rdp) {
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("Check"));
rcu_nocb_lock_irqsave(rdp, flags);
@@ -2411,13 +2440,12 @@ static void show_rcu_nocb_state(struct rcu_data *rdp)
return;
waslocked = raw_spin_is_locked(&rdp->nocb_gp_lock);
- wastimer = timer_pending(&rdp->nocb_timer);
+ wastimer = timer_pending(&rdp->nocb_bypass_timer);
wassleep = swait_active(&rdp->nocb_gp_wq);
- if (!rdp->nocb_defer_wakeup && !rdp->nocb_gp_sleep &&
- !waslocked && !wastimer && !wassleep)
+ if (!rdp->nocb_gp_sleep && !waslocked && !wastimer && !wassleep)
return; /* Nothing untowards. */
- pr_info(" !!! %c%c%c%c %c\n",
+ pr_info(" nocb GP activity on CB-only CPU!!! %c%c%c%c %c\n",
"lL"[waslocked],
"dD"[!!rdp->nocb_defer_wakeup],
"tT"[wastimer],
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index b5d3b4794db4..0fde39b8daab 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -158,7 +158,7 @@ static void rcu_stall_kick_kthreads(void)
{
unsigned long j;
- if (!rcu_kick_kthreads)
+ if (!READ_ONCE(rcu_kick_kthreads))
return;
j = READ_ONCE(rcu_state.jiffies_kick_kthreads);
if (time_after(jiffies, j) && rcu_state.gp_kthread &&
@@ -580,7 +580,7 @@ static void check_cpu_stall(struct rcu_data *rdp)
unsigned long js;
struct rcu_node *rnp;
- if ((rcu_stall_is_suppressed() && !rcu_kick_kthreads) ||
+ if ((rcu_stall_is_suppressed() && !READ_ONCE(rcu_kick_kthreads)) ||
!rcu_gp_in_progress())
return;
rcu_stall_kick_kthreads();
@@ -623,7 +623,7 @@ static void check_cpu_stall(struct rcu_data *rdp)
/* We haven't checked in, so go dump stack. */
print_cpu_stall(gps);
- if (rcu_cpu_stall_ftrace_dump)
+ if (READ_ONCE(rcu_cpu_stall_ftrace_dump))
rcu_ftrace_dump(DUMP_ALL);
} else if (rcu_gp_in_progress() &&
@@ -632,7 +632,7 @@ static void check_cpu_stall(struct rcu_data *rdp)
/* They had a few time units to dump stack, so complain. */
print_other_cpu_stall(gs2, gps);
- if (rcu_cpu_stall_ftrace_dump)
+ if (READ_ONCE(rcu_cpu_stall_ftrace_dump))
rcu_ftrace_dump(DUMP_ALL);
}
}
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 3e0f4bcb558f..39334d2d2b37 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -53,19 +53,6 @@
#endif
#define MODULE_PARAM_PREFIX "rcupdate."
-#ifndef data_race
-#define data_race(expr) \
- ({ \
- expr; \
- })
-#endif
-#ifndef ASSERT_EXCLUSIVE_WRITER
-#define ASSERT_EXCLUSIVE_WRITER(var) do { } while (0)
-#endif
-#ifndef ASSERT_EXCLUSIVE_ACCESS
-#define ASSERT_EXCLUSIVE_ACCESS(var) do { } while (0)
-#endif
-
#ifndef CONFIG_TINY_RCU
module_param(rcu_expedited, int, 0);
module_param(rcu_normal, int, 0);
diff --git a/kernel/scftorture.c b/kernel/scftorture.c
new file mode 100644
index 000000000000..554a521ee235
--- /dev/null
+++ b/kernel/scftorture.c
@@ -0,0 +1,575 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Torture test for smp_call_function() and friends.
+//
+// Copyright (C) Facebook, 2020.
+//
+// Author: Paul E. McKenney <paulmck@kernel.org>
+
+#define pr_fmt(fmt) fmt
+
+#include <linux/atomic.h>
+#include <linux/bitops.h>
+#include <linux/completion.h>
+#include <linux/cpu.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kthread.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/notifier.h>
+#include <linux/percpu.h>
+#include <linux/rcupdate.h>
+#include <linux/rcupdate_trace.h>
+#include <linux/reboot.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/smp.h>
+#include <linux/stat.h>
+#include <linux/srcu.h>
+#include <linux/slab.h>
+#include <linux/torture.h>
+#include <linux/types.h>
+
+#define SCFTORT_STRING "scftorture"
+#define SCFTORT_FLAG SCFTORT_STRING ": "
+
+#define SCFTORTOUT(s, x...) \
+ pr_alert(SCFTORT_FLAG s, ## x)
+
+#define VERBOSE_SCFTORTOUT(s, x...) \
+ do { if (verbose) pr_alert(SCFTORT_FLAG s, ## x); } while (0)
+
+#define VERBOSE_SCFTORTOUT_ERRSTRING(s, x...) \
+ do { if (verbose) pr_alert(SCFTORT_FLAG "!!! " s, ## x); } while (0)
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Paul E. McKenney <paulmck@kernel.org>");
+
+// Wait until there are multiple CPUs before starting test.
+torture_param(int, holdoff, IS_BUILTIN(CONFIG_SCF_TORTURE_TEST) ? 10 : 0,
+ "Holdoff time before test start (s)");
+torture_param(int, longwait, 0, "Include ridiculously long waits? (seconds)");
+torture_param(int, nthreads, -1, "# threads, defaults to -1 for all CPUs.");
+torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
+torture_param(int, onoff_interval, 0, "Time between CPU hotplugs (s), 0=disable");
+torture_param(int, shutdown_secs, 0, "Shutdown time (ms), <= zero to disable.");
+torture_param(int, stat_interval, 60, "Number of seconds between stats printk()s.");
+torture_param(int, stutter_cpus, 5, "Number of jiffies to change CPUs under test, 0=disable");
+torture_param(bool, use_cpus_read_lock, 0, "Use cpus_read_lock() to exclude CPU hotplug.");
+torture_param(int, verbose, 0, "Enable verbose debugging printk()s");
+torture_param(int, weight_single, -1, "Testing weight for single-CPU no-wait operations.");
+torture_param(int, weight_single_wait, -1, "Testing weight for single-CPU operations.");
+torture_param(int, weight_many, -1, "Testing weight for multi-CPU no-wait operations.");
+torture_param(int, weight_many_wait, -1, "Testing weight for multi-CPU operations.");
+torture_param(int, weight_all, -1, "Testing weight for all-CPU no-wait operations.");
+torture_param(int, weight_all_wait, -1, "Testing weight for all-CPU operations.");
+
+char *torture_type = "";
+
+#ifdef MODULE
+# define SCFTORT_SHUTDOWN 0
+#else
+# define SCFTORT_SHUTDOWN 1
+#endif
+
+torture_param(bool, shutdown, SCFTORT_SHUTDOWN, "Shutdown at end of torture test.");
+
+struct scf_statistics {
+ struct task_struct *task;
+ int cpu;
+ long long n_single;
+ long long n_single_ofl;
+ long long n_single_wait;
+ long long n_single_wait_ofl;
+ long long n_many;
+ long long n_many_wait;
+ long long n_all;
+ long long n_all_wait;
+};
+
+static struct scf_statistics *scf_stats_p;
+static struct task_struct *scf_torture_stats_task;
+static DEFINE_PER_CPU(long long, scf_invoked_count);
+
+// Data for random primitive selection
+#define SCF_PRIM_SINGLE 0
+#define SCF_PRIM_MANY 1
+#define SCF_PRIM_ALL 2
+#define SCF_NPRIMS (2 * 3) // Need wait and no-wait versions of each.
+
+static char *scf_prim_name[] = {
+ "smp_call_function_single",
+ "smp_call_function_many",
+ "smp_call_function",
+};
+
+struct scf_selector {
+ unsigned long scfs_weight;
+ int scfs_prim;
+ bool scfs_wait;
+};
+static struct scf_selector scf_sel_array[SCF_NPRIMS];
+static int scf_sel_array_len;
+static unsigned long scf_sel_totweight;
+
+// Communicate between caller and handler.
+struct scf_check {
+ bool scfc_in;
+ bool scfc_out;
+ int scfc_cpu; // -1 for not _single().
+ bool scfc_wait;
+};
+
+// Use to wait for all threads to start.
+static atomic_t n_started;
+static atomic_t n_errs;
+static atomic_t n_mb_in_errs;
+static atomic_t n_mb_out_errs;
+static atomic_t n_alloc_errs;
+static bool scfdone;
+static char *bangstr = "";
+
+static DEFINE_TORTURE_RANDOM_PERCPU(scf_torture_rand);
+
+// Print torture statistics. Caller must ensure serialization.
+static void scf_torture_stats_print(void)
+{
+ int cpu;
+ int i;
+ long long invoked_count = 0;
+ bool isdone = READ_ONCE(scfdone);
+ struct scf_statistics scfs = {};
+
+ for_each_possible_cpu(cpu)
+ invoked_count += data_race(per_cpu(scf_invoked_count, cpu));
+ for (i = 0; i < nthreads; i++) {
+ scfs.n_single += scf_stats_p[i].n_single;
+ scfs.n_single_ofl += scf_stats_p[i].n_single_ofl;
+ scfs.n_single_wait += scf_stats_p[i].n_single_wait;
+ scfs.n_single_wait_ofl += scf_stats_p[i].n_single_wait_ofl;
+ scfs.n_many += scf_stats_p[i].n_many;
+ scfs.n_many_wait += scf_stats_p[i].n_many_wait;
+ scfs.n_all += scf_stats_p[i].n_all;
+ scfs.n_all_wait += scf_stats_p[i].n_all_wait;
+ }
+ if (atomic_read(&n_errs) || atomic_read(&n_mb_in_errs) ||
+ atomic_read(&n_mb_out_errs) || atomic_read(&n_alloc_errs))
+ bangstr = "!!! ";
+ pr_alert("%s %sscf_invoked_count %s: %lld single: %lld/%lld single_ofl: %lld/%lld many: %lld/%lld all: %lld/%lld ",
+ SCFTORT_FLAG, bangstr, isdone ? "VER" : "ver", invoked_count,
+ scfs.n_single, scfs.n_single_wait, scfs.n_single_ofl, scfs.n_single_wait_ofl,
+ scfs.n_many, scfs.n_many_wait, scfs.n_all, scfs.n_all_wait);
+ torture_onoff_stats();
+ pr_cont("ste: %d stnmie: %d stnmoe: %d staf: %d\n", atomic_read(&n_errs),
+ atomic_read(&n_mb_in_errs), atomic_read(&n_mb_out_errs),
+ atomic_read(&n_alloc_errs));
+}
+
+// Periodically prints torture statistics, if periodic statistics printing
+// was specified via the stat_interval module parameter.
+static int
+scf_torture_stats(void *arg)
+{
+ VERBOSE_TOROUT_STRING("scf_torture_stats task started");
+ do {
+ schedule_timeout_interruptible(stat_interval * HZ);
+ scf_torture_stats_print();
+ torture_shutdown_absorb("scf_torture_stats");
+ } while (!torture_must_stop());
+ torture_kthread_stopping("scf_torture_stats");
+ return 0;
+}
+
+// Add a primitive to the scf_sel_array[].
+static void scf_sel_add(unsigned long weight, int prim, bool wait)
+{
+ struct scf_selector *scfsp = &scf_sel_array[scf_sel_array_len];
+
+ // If no weight, if array would overflow, if computing three-place
+ // percentages would overflow, or if the scf_prim_name[] array would
+ // overflow, don't bother. In the last three two cases, complain.
+ if (!weight ||
+ WARN_ON_ONCE(scf_sel_array_len >= ARRAY_SIZE(scf_sel_array)) ||
+ WARN_ON_ONCE(0 - 100000 * weight <= 100000 * scf_sel_totweight) ||
+ WARN_ON_ONCE(prim >= ARRAY_SIZE(scf_prim_name)))
+ return;
+ scf_sel_totweight += weight;
+ scfsp->scfs_weight = scf_sel_totweight;
+ scfsp->scfs_prim = prim;
+ scfsp->scfs_wait = wait;
+ scf_sel_array_len++;
+}
+
+// Dump out weighting percentages for scf_prim_name[] array.
+static void scf_sel_dump(void)
+{
+ int i;
+ unsigned long oldw = 0;
+ struct scf_selector *scfsp;
+ unsigned long w;
+
+ for (i = 0; i < scf_sel_array_len; i++) {
+ scfsp = &scf_sel_array[i];
+ w = (scfsp->scfs_weight - oldw) * 100000 / scf_sel_totweight;
+ pr_info("%s: %3lu.%03lu %s(%s)\n", __func__, w / 1000, w % 1000,
+ scf_prim_name[scfsp->scfs_prim],
+ scfsp->scfs_wait ? "wait" : "nowait");
+ oldw = scfsp->scfs_weight;
+ }
+}
+
+// Randomly pick a primitive and wait/nowait, based on weightings.
+static struct scf_selector *scf_sel_rand(struct torture_random_state *trsp)
+{
+ int i;
+ unsigned long w = torture_random(trsp) % (scf_sel_totweight + 1);
+
+ for (i = 0; i < scf_sel_array_len; i++)
+ if (scf_sel_array[i].scfs_weight >= w)
+ return &scf_sel_array[i];
+ WARN_ON_ONCE(1);
+ return &scf_sel_array[0];
+}
+
+// Update statistics and occasionally burn up mass quantities of CPU time,
+// if told to do so via scftorture.longwait. Otherwise, occasionally burn
+// a little bit.
+static void scf_handler(void *scfc_in)
+{
+ int i;
+ int j;
+ unsigned long r = torture_random(this_cpu_ptr(&scf_torture_rand));
+ struct scf_check *scfcp = scfc_in;
+
+ if (likely(scfcp)) {
+ WRITE_ONCE(scfcp->scfc_out, false); // For multiple receivers.
+ if (WARN_ON_ONCE(unlikely(!READ_ONCE(scfcp->scfc_in))))
+ atomic_inc(&n_mb_in_errs);
+ }
+ this_cpu_inc(scf_invoked_count);
+ if (longwait <= 0) {
+ if (!(r & 0xffc0))
+ udelay(r & 0x3f);
+ goto out;
+ }
+ if (r & 0xfff)
+ goto out;
+ r = (r >> 12);
+ if (longwait <= 0) {
+ udelay((r & 0xff) + 1);
+ goto out;
+ }
+ r = r % longwait + 1;
+ for (i = 0; i < r; i++) {
+ for (j = 0; j < 1000; j++) {
+ udelay(1000);
+ cpu_relax();
+ }
+ }
+out:
+ if (unlikely(!scfcp))
+ return;
+ if (scfcp->scfc_wait)
+ WRITE_ONCE(scfcp->scfc_out, true);
+ else
+ kfree(scfcp);
+}
+
+// As above, but check for correct CPU.
+static void scf_handler_1(void *scfc_in)
+{
+ struct scf_check *scfcp = scfc_in;
+
+ if (likely(scfcp) && WARN_ONCE(smp_processor_id() != scfcp->scfc_cpu, "%s: Wanted CPU %d got CPU %d\n", __func__, scfcp->scfc_cpu, smp_processor_id())) {
+ atomic_inc(&n_errs);
+ }
+ scf_handler(scfcp);
+}
+
+// Randomly do an smp_call_function*() invocation.
+static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_random_state *trsp)
+{
+ uintptr_t cpu;
+ int ret = 0;
+ struct scf_check *scfcp = NULL;
+ struct scf_selector *scfsp = scf_sel_rand(trsp);
+
+ if (use_cpus_read_lock)
+ cpus_read_lock();
+ else
+ preempt_disable();
+ if (scfsp->scfs_prim == SCF_PRIM_SINGLE || scfsp->scfs_wait) {
+ scfcp = kmalloc(sizeof(*scfcp), GFP_ATOMIC);
+ if (WARN_ON_ONCE(!scfcp)) {
+ atomic_inc(&n_alloc_errs);
+ } else {
+ scfcp->scfc_cpu = -1;
+ scfcp->scfc_wait = scfsp->scfs_wait;
+ scfcp->scfc_out = false;
+ }
+ }
+ switch (scfsp->scfs_prim) {
+ case SCF_PRIM_SINGLE:
+ cpu = torture_random(trsp) % nr_cpu_ids;
+ if (scfsp->scfs_wait)
+ scfp->n_single_wait++;
+ else
+ scfp->n_single++;
+ if (scfcp) {
+ scfcp->scfc_cpu = cpu;
+ barrier(); // Prevent race-reduction compiler optimizations.
+ scfcp->scfc_in = true;
+ }
+ ret = smp_call_function_single(cpu, scf_handler_1, (void *)scfcp, scfsp->scfs_wait);
+ if (ret) {
+ if (scfsp->scfs_wait)
+ scfp->n_single_wait_ofl++;
+ else
+ scfp->n_single_ofl++;
+ kfree(scfcp);
+ scfcp = NULL;
+ }
+ break;
+ case SCF_PRIM_MANY:
+ if (scfsp->scfs_wait)
+ scfp->n_many_wait++;
+ else
+ scfp->n_many++;
+ if (scfcp) {
+ barrier(); // Prevent race-reduction compiler optimizations.
+ scfcp->scfc_in = true;
+ }
+ smp_call_function_many(cpu_online_mask, scf_handler, scfcp, scfsp->scfs_wait);
+ break;
+ case SCF_PRIM_ALL:
+ if (scfsp->scfs_wait)
+ scfp->n_all_wait++;
+ else
+ scfp->n_all++;
+ if (scfcp) {
+ barrier(); // Prevent race-reduction compiler optimizations.
+ scfcp->scfc_in = true;
+ }
+ smp_call_function(scf_handler, scfcp, scfsp->scfs_wait);
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ if (scfcp)
+ scfcp->scfc_out = true;
+ }
+ if (scfcp && scfsp->scfs_wait) {
+ if (WARN_ON_ONCE((num_online_cpus() > 1 || scfsp->scfs_prim == SCF_PRIM_SINGLE) &&
+ !scfcp->scfc_out))
+ atomic_inc(&n_mb_out_errs); // Leak rather than trash!
+ else
+ kfree(scfcp);
+ barrier(); // Prevent race-reduction compiler optimizations.
+ }
+ if (use_cpus_read_lock)
+ cpus_read_unlock();
+ else
+ preempt_enable();
+ if (!(torture_random(trsp) & 0xfff))
+ schedule_timeout_uninterruptible(1);
+}
+
+// SCF test kthread. Repeatedly does calls to members of the
+// smp_call_function() family of functions.
+static int scftorture_invoker(void *arg)
+{
+ int cpu;
+ DEFINE_TORTURE_RANDOM(rand);
+ struct scf_statistics *scfp = (struct scf_statistics *)arg;
+ bool was_offline = false;
+
+ VERBOSE_SCFTORTOUT("scftorture_invoker %d: task started", scfp->cpu);
+ cpu = scfp->cpu % nr_cpu_ids;
+ set_cpus_allowed_ptr(current, cpumask_of(cpu));
+ set_user_nice(current, MAX_NICE);
+ if (holdoff)
+ schedule_timeout_interruptible(holdoff * HZ);
+
+ VERBOSE_SCFTORTOUT("scftorture_invoker %d: Waiting for all SCF torturers from cpu %d", scfp->cpu, smp_processor_id());
+
+ // Make sure that the CPU is affinitized appropriately during testing.
+ WARN_ON_ONCE(smp_processor_id() != scfp->cpu);
+
+ if (!atomic_dec_return(&n_started))
+ while (atomic_read_acquire(&n_started)) {
+ if (torture_must_stop()) {
+ VERBOSE_SCFTORTOUT("scftorture_invoker %d ended before starting", scfp->cpu);
+ goto end;
+ }
+ schedule_timeout_uninterruptible(1);
+ }
+
+ VERBOSE_SCFTORTOUT("scftorture_invoker %d started", scfp->cpu);
+
+ do {
+ scftorture_invoke_one(scfp, &rand);
+ while (cpu_is_offline(cpu) && !torture_must_stop()) {
+ schedule_timeout_interruptible(HZ / 5);
+ was_offline = true;
+ }
+ if (was_offline) {
+ set_cpus_allowed_ptr(current, cpumask_of(cpu));
+ was_offline = false;
+ }
+ cond_resched();
+ } while (!torture_must_stop());
+
+ VERBOSE_SCFTORTOUT("scftorture_invoker %d ended", scfp->cpu);
+end:
+ torture_kthread_stopping("scftorture_invoker");
+ return 0;
+}
+
+static void
+scftorture_print_module_parms(const char *tag)
+{
+ pr_alert(SCFTORT_FLAG
+ "--- %s: verbose=%d holdoff=%d longwait=%d nthreads=%d onoff_holdoff=%d onoff_interval=%d shutdown_secs=%d stat_interval=%d stutter_cpus=%d use_cpus_read_lock=%d, weight_single=%d, weight_single_wait=%d, weight_many=%d, weight_many_wait=%d, weight_all=%d, weight_all_wait=%d\n", tag,
+ verbose, holdoff, longwait, nthreads, onoff_holdoff, onoff_interval, shutdown, stat_interval, stutter_cpus, use_cpus_read_lock, weight_single, weight_single_wait, weight_many, weight_many_wait, weight_all, weight_all_wait);
+}
+
+static void scf_cleanup_handler(void *unused)
+{
+}
+
+static void scf_torture_cleanup(void)
+{
+ int i;
+
+ if (torture_cleanup_begin())
+ return;
+
+ WRITE_ONCE(scfdone, true);
+ if (nthreads)
+ for (i = 0; i < nthreads; i++)
+ torture_stop_kthread("scftorture_invoker", scf_stats_p[i].task);
+ else
+ goto end;
+ smp_call_function(scf_cleanup_handler, NULL, 0);
+ torture_stop_kthread(scf_torture_stats, scf_torture_stats_task);
+ scf_torture_stats_print(); // -After- the stats thread is stopped!
+ kfree(scf_stats_p); // -After- the last stats print has completed!
+ scf_stats_p = NULL;
+
+ if (atomic_read(&n_errs) || atomic_read(&n_mb_in_errs) || atomic_read(&n_mb_out_errs))
+ scftorture_print_module_parms("End of test: FAILURE");
+ else if (torture_onoff_failures())
+ scftorture_print_module_parms("End of test: LOCK_HOTPLUG");
+ else
+ scftorture_print_module_parms("End of test: SUCCESS");
+
+end:
+ torture_cleanup_end();
+}
+
+static int __init scf_torture_init(void)
+{
+ long i;
+ int firsterr = 0;
+ unsigned long weight_single1 = weight_single;
+ unsigned long weight_single_wait1 = weight_single_wait;
+ unsigned long weight_many1 = weight_many;
+ unsigned long weight_many_wait1 = weight_many_wait;
+ unsigned long weight_all1 = weight_all;
+ unsigned long weight_all_wait1 = weight_all_wait;
+
+ if (!torture_init_begin(SCFTORT_STRING, verbose))
+ return -EBUSY;
+
+ scftorture_print_module_parms("Start of test");
+
+ if (weight_single == -1 && weight_single_wait == -1 &&
+ weight_many == -1 && weight_many_wait == -1 &&
+ weight_all == -1 && weight_all_wait == -1) {
+ weight_single1 = 2 * nr_cpu_ids;
+ weight_single_wait1 = 2 * nr_cpu_ids;
+ weight_many1 = 2;
+ weight_many_wait1 = 2;
+ weight_all1 = 1;
+ weight_all_wait1 = 1;
+ } else {
+ if (weight_single == -1)
+ weight_single1 = 0;
+ if (weight_single_wait == -1)
+ weight_single_wait1 = 0;
+ if (weight_many == -1)
+ weight_many1 = 0;
+ if (weight_many_wait == -1)
+ weight_many_wait1 = 0;
+ if (weight_all == -1)
+ weight_all1 = 0;
+ if (weight_all_wait == -1)
+ weight_all_wait1 = 0;
+ }
+ if (weight_single1 == 0 && weight_single_wait1 == 0 &&
+ weight_many1 == 0 && weight_many_wait1 == 0 &&
+ weight_all1 == 0 && weight_all_wait1 == 0) {
+ VERBOSE_SCFTORTOUT_ERRSTRING("all zero weights makes no sense");
+ firsterr = -EINVAL;
+ goto unwind;
+ }
+ scf_sel_add(weight_single1, SCF_PRIM_SINGLE, false);
+ scf_sel_add(weight_single_wait1, SCF_PRIM_SINGLE, true);
+ scf_sel_add(weight_many1, SCF_PRIM_MANY, false);
+ scf_sel_add(weight_many_wait1, SCF_PRIM_MANY, true);
+ scf_sel_add(weight_all1, SCF_PRIM_ALL, false);
+ scf_sel_add(weight_all_wait1, SCF_PRIM_ALL, true);
+ scf_sel_dump();
+
+ if (onoff_interval > 0) {
+ firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval, NULL);
+ if (firsterr)
+ goto unwind;
+ }
+ if (shutdown_secs > 0) {
+ firsterr = torture_shutdown_init(shutdown_secs, scf_torture_cleanup);
+ if (firsterr)
+ goto unwind;
+ }
+
+ // Worker tasks invoking smp_call_function().
+ if (nthreads < 0)
+ nthreads = num_online_cpus();
+ scf_stats_p = kcalloc(nthreads, sizeof(scf_stats_p[0]), GFP_KERNEL);
+ if (!scf_stats_p) {
+ VERBOSE_SCFTORTOUT_ERRSTRING("out of memory");
+ firsterr = -ENOMEM;
+ goto unwind;
+ }
+
+ VERBOSE_SCFTORTOUT("Starting %d smp_call_function() threads\n", nthreads);
+
+ atomic_set(&n_started, nthreads);
+ for (i = 0; i < nthreads; i++) {
+ scf_stats_p[i].cpu = i;
+ firsterr = torture_create_kthread(scftorture_invoker, (void *)&scf_stats_p[i],
+ scf_stats_p[i].task);
+ if (firsterr)
+ goto unwind;
+ }
+ if (stat_interval > 0) {
+ firsterr = torture_create_kthread(scf_torture_stats, NULL, scf_torture_stats_task);
+ if (firsterr)
+ goto unwind;
+ }
+
+ torture_init_end();
+ return 0;
+
+unwind:
+ torture_init_end();
+ scf_torture_cleanup();
+ return firsterr;
+}
+
+module_init(scf_torture_init);
+module_exit(scf_torture_cleanup);
diff --git a/kernel/smp.c b/kernel/smp.c
index d9832a171046..4d17501433be 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -20,6 +20,9 @@
#include <linux/sched.h>
#include <linux/sched/idle.h>
#include <linux/hypervisor.h>
+#include <linux/sched/clock.h>
+#include <linux/nmi.h>
+#include <linux/sched/debug.h>
#include "smpboot.h"
#include "sched/smp.h"
@@ -96,6 +99,103 @@ void __init call_function_init(void)
smpcfd_prepare_cpu(smp_processor_id());
}
+#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
+
+static DEFINE_PER_CPU(call_single_data_t *, cur_csd);
+static DEFINE_PER_CPU(smp_call_func_t, cur_csd_func);
+static DEFINE_PER_CPU(void *, cur_csd_info);
+
+#define CSD_LOCK_TIMEOUT (5ULL * NSEC_PER_SEC)
+static atomic_t csd_bug_count = ATOMIC_INIT(0);
+
+/* Record current CSD work for current CPU, NULL to erase. */
+static void csd_lock_record(call_single_data_t *csd)
+{
+ if (!csd) {
+ smp_mb(); /* NULL cur_csd after unlock. */
+ __this_cpu_write(cur_csd, NULL);
+ return;
+ }
+ __this_cpu_write(cur_csd_func, csd->func);
+ __this_cpu_write(cur_csd_info, csd->info);
+ smp_wmb(); /* func and info before csd. */
+ __this_cpu_write(cur_csd, csd);
+ smp_mb(); /* Update cur_csd before function call. */
+ /* Or before unlock, as the case may be. */
+}
+
+static __always_inline int csd_lock_wait_getcpu(call_single_data_t *csd)
+{
+ unsigned int csd_type;
+
+ csd_type = CSD_TYPE(csd);
+ if (csd_type == CSD_TYPE_ASYNC || csd_type == CSD_TYPE_SYNC)
+ return csd->dst; /* Other CSD_TYPE_ values might not have ->dst. */
+ return -1;
+}
+
+/*
+ * Complain if too much time spent waiting. Note that only
+ * the CSD_TYPE_SYNC/ASYNC types provide the destination CPU,
+ * so waiting on other types gets much less information.
+ */
+static __always_inline bool csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, int *bug_id)
+{
+ int cpu = -1;
+ int cpux;
+ bool firsttime;
+ u64 ts2, ts_delta;
+ call_single_data_t *cpu_cur_csd;
+ unsigned int flags = READ_ONCE(csd->flags);
+
+ if (!(flags & CSD_FLAG_LOCK)) {
+ if (!unlikely(*bug_id))
+ return true;
+ cpu = csd_lock_wait_getcpu(csd);
+ pr_alert("csd: CSD lock (#%d) got unstuck on CPU#%02d, CPU#%02d released the lock.\n",
+ *bug_id, raw_smp_processor_id(), cpu);
+ return true;
+ }
+
+ ts2 = sched_clock();
+ ts_delta = ts2 - *ts1;
+ if (likely(ts_delta <= CSD_LOCK_TIMEOUT))
+ return false;
+
+ firsttime = !*bug_id;
+ if (firsttime)
+ *bug_id = atomic_inc_return(&csd_bug_count);
+ cpu = csd_lock_wait_getcpu(csd);
+ if (WARN_ONCE(cpu < 0 || cpu >= nr_cpu_ids, "%s: cpu = %d\n", __func__, cpu))
+ cpux = 0;
+ else
+ cpux = cpu;
+ cpu_cur_csd = smp_load_acquire(&per_cpu(cur_csd, cpux)); /* Before func and info. */
+ pr_alert("csd: %s non-responsive CSD lock (#%d) on CPU#%d, waiting %llu ns for CPU#%02d %pS(%ps).\n",
+ firsttime ? "Detected" : "Continued", *bug_id, raw_smp_processor_id(), ts2 - ts0,
+ cpu, csd->func, csd->info);
+ if (cpu_cur_csd && csd != cpu_cur_csd) {
+ pr_alert("\tcsd: CSD lock (#%d) handling prior %pS(%ps) request.\n",
+ *bug_id, READ_ONCE(per_cpu(cur_csd_func, cpux)),
+ READ_ONCE(per_cpu(cur_csd_info, cpux)));
+ } else {
+ pr_alert("\tcsd: CSD lock (#%d) %s.\n",
+ *bug_id, !cpu_cur_csd ? "unresponsive" : "handling this request");
+ }
+ if (cpu >= 0) {
+ if (!trigger_single_cpu_backtrace(cpu))
+ dump_cpu_task(cpu);
+ if (!cpu_cur_csd) {
+ pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n", *bug_id, raw_smp_processor_id(), cpu);
+ arch_send_call_function_single_ipi(cpu);
+ }
+ }
+ dump_stack();
+ *ts1 = ts2;
+
+ return false;
+}
+
/*
* csd_lock/csd_unlock used to serialize access to per-cpu csd resources
*
@@ -105,8 +205,28 @@ void __init call_function_init(void)
*/
static __always_inline void csd_lock_wait(call_single_data_t *csd)
{
+ int bug_id = 0;
+ u64 ts0, ts1;
+
+ ts1 = ts0 = sched_clock();
+ for (;;) {
+ if (csd_lock_wait_toolong(csd, ts0, &ts1, &bug_id))
+ break;
+ cpu_relax();
+ }
+ smp_acquire__after_ctrl_dep();
+}
+
+#else
+static void csd_lock_record(call_single_data_t *csd)
+{
+}
+
+static __always_inline void csd_lock_wait(call_single_data_t *csd)
+{
smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK));
}
+#endif
static __always_inline void csd_lock(call_single_data_t *csd)
{
@@ -166,9 +286,11 @@ static int generic_exec_single(int cpu, call_single_data_t *csd)
* We can unlock early even for the synchronous on-stack case,
* since we're doing this from the same CPU..
*/
+ csd_lock_record(csd);
csd_unlock(csd);
local_irq_save(flags);
func(info);
+ csd_lock_record(NULL);
local_irq_restore(flags);
return 0;
}
@@ -268,8 +390,10 @@ static void flush_smp_call_function_queue(bool warn_cpu_offline)
entry = &csd_next->llist;
}
+ csd_lock_record(csd);
func(info);
csd_unlock(csd);
+ csd_lock_record(NULL);
} else {
prev = &csd->llist;
}
@@ -296,8 +420,10 @@ static void flush_smp_call_function_queue(bool warn_cpu_offline)
smp_call_func_t func = csd->func;
void *info = csd->info;
+ csd_lock_record(csd);
csd_unlock(csd);
func(info);
+ csd_lock_record(NULL);
} else if (type == CSD_TYPE_IRQ_WORK) {
irq_work_single(csd);
}
@@ -375,6 +501,10 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
csd->func = func;
csd->info = info;
+#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
+ csd->src = smp_processor_id();
+ csd->dst = cpu;
+#endif
err = generic_exec_single(cpu, csd);
@@ -540,6 +670,10 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
csd->flags |= CSD_TYPE_SYNC;
csd->func = func;
csd->info = info;
+#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
+ csd->src = smp_processor_id();
+ csd->dst = cpu;
+#endif
if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
__cpumask_set_cpu(cpu, cfd->cpumask_ipi);
}
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index f0199a4ba1ad..81632cd5e3b7 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -927,7 +927,7 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
if (ratelimit < 10 &&
(local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) {
- pr_warn("NOHZ: local_softirq_pending %02x\n",
+ pr_warn("NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #%02x!!!\n",
(unsigned int) local_softirq_pending());
ratelimit++;
}
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