diff options
Diffstat (limited to 'patches/0024-jump_label-Reorder-hotplug-lock-and-jump_label_lock.patch')
| -rw-r--r-- | patches/0024-jump_label-Reorder-hotplug-lock-and-jump_label_lock.patch | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/patches/0024-jump_label-Reorder-hotplug-lock-and-jump_label_lock.patch b/patches/0024-jump_label-Reorder-hotplug-lock-and-jump_label_lock.patch new file mode 100644 index 000000000000..4031d4091409 --- /dev/null +++ b/patches/0024-jump_label-Reorder-hotplug-lock-and-jump_label_lock.patch @@ -0,0 +1,221 @@ +From f2545b2d4ce13e068897ef60ae64dffe215f4152 Mon Sep 17 00:00:00 2001 +From: Thomas Gleixner <tglx@linutronix.de> +Date: Wed, 24 May 2017 10:15:35 +0200 +Subject: [PATCH 24/32] jump_label: Reorder hotplug lock and jump_label_lock + +The conversion of the hotplug locking to a percpu rwsem unearthed lock +ordering issues all over the place. + +The jump_label code has two issues: + + 1) Nested get_online_cpus() invocations + + 2) Ordering problems vs. the cpus rwsem and the jump_label_mutex + +To cure these, the following lock order has been established; + + cpus_rwsem -> jump_label_lock -> text_mutex + +Even if not all architectures need protection against CPU hotplug, taking +cpus_rwsem before jump_label_lock is now mandatory in code pathes which +actually modify code and therefor need text_mutex protection. + +Move the get_online_cpus() invocations into the core jump label code and +establish the proper lock order where required. + +Signed-off-by: Thomas Gleixner <tglx@linutronix.de> +Acked-by: Ingo Molnar <mingo@kernel.org> +Acked-by: "David S. Miller" <davem@davemloft.net> +Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> +Cc: Chris Metcalf <cmetcalf@mellanox.com> +Cc: Peter Zijlstra <peterz@infradead.org> +Cc: Sebastian Siewior <bigeasy@linutronix.de> +Cc: Steven Rostedt <rostedt@goodmis.org> +Cc: Jason Baron <jbaron@akamai.com> +Cc: Ralf Baechle <ralf@linux-mips.org> +Link: http://lkml.kernel.org/r/20170524081549.025830817@linutronix.de +--- + arch/mips/kernel/jump_label.c | 2 -- + arch/sparc/kernel/jump_label.c | 2 -- + arch/tile/kernel/jump_label.c | 2 -- + arch/x86/kernel/jump_label.c | 2 -- + kernel/jump_label.c | 20 ++++++++++++++------ + 5 files changed, 14 insertions(+), 14 deletions(-) + +diff --git a/arch/mips/kernel/jump_label.c b/arch/mips/kernel/jump_label.c +index 3e586daa3a32..32e3168316cd 100644 +--- a/arch/mips/kernel/jump_label.c ++++ b/arch/mips/kernel/jump_label.c +@@ -58,7 +58,6 @@ void arch_jump_label_transform(struct jump_entry *e, + insn.word = 0; /* nop */ + } + +- get_online_cpus(); + mutex_lock(&text_mutex); + if (IS_ENABLED(CONFIG_CPU_MICROMIPS)) { + insn_p->halfword[0] = insn.word >> 16; +@@ -70,7 +69,6 @@ void arch_jump_label_transform(struct jump_entry *e, + (unsigned long)insn_p + sizeof(*insn_p)); + + mutex_unlock(&text_mutex); +- put_online_cpus(); + } + + #endif /* HAVE_JUMP_LABEL */ +diff --git a/arch/sparc/kernel/jump_label.c b/arch/sparc/kernel/jump_label.c +index 07933b9e9ce0..93adde1ac166 100644 +--- a/arch/sparc/kernel/jump_label.c ++++ b/arch/sparc/kernel/jump_label.c +@@ -41,12 +41,10 @@ void arch_jump_label_transform(struct jump_entry *entry, + val = 0x01000000; + } + +- get_online_cpus(); + mutex_lock(&text_mutex); + *insn = val; + flushi(insn); + mutex_unlock(&text_mutex); +- put_online_cpus(); + } + + #endif +diff --git a/arch/tile/kernel/jump_label.c b/arch/tile/kernel/jump_label.c +index 07802d586988..93931a46625b 100644 +--- a/arch/tile/kernel/jump_label.c ++++ b/arch/tile/kernel/jump_label.c +@@ -45,14 +45,12 @@ static void __jump_label_transform(struct jump_entry *e, + void arch_jump_label_transform(struct jump_entry *e, + enum jump_label_type type) + { +- get_online_cpus(); + mutex_lock(&text_mutex); + + __jump_label_transform(e, type); + flush_icache_range(e->code, e->code + sizeof(tilegx_bundle_bits)); + + mutex_unlock(&text_mutex); +- put_online_cpus(); + } + + __init_or_module void arch_jump_label_transform_static(struct jump_entry *e, +diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c +index c37bd0f39c70..ab4f491da2a9 100644 +--- a/arch/x86/kernel/jump_label.c ++++ b/arch/x86/kernel/jump_label.c +@@ -105,11 +105,9 @@ static void __jump_label_transform(struct jump_entry *entry, + void arch_jump_label_transform(struct jump_entry *entry, + enum jump_label_type type) + { +- get_online_cpus(); + mutex_lock(&text_mutex); + __jump_label_transform(entry, type, NULL, 0); + mutex_unlock(&text_mutex); +- put_online_cpus(); + } + + static enum { +diff --git a/kernel/jump_label.c b/kernel/jump_label.c +index 6c9cb208ac48..d11c506a6ac3 100644 +--- a/kernel/jump_label.c ++++ b/kernel/jump_label.c +@@ -15,6 +15,7 @@ + #include <linux/static_key.h> + #include <linux/jump_label_ratelimit.h> + #include <linux/bug.h> ++#include <linux/cpu.h> + + #ifdef HAVE_JUMP_LABEL + +@@ -124,6 +125,7 @@ void static_key_slow_inc(struct static_key *key) + return; + } + ++ cpus_read_lock(); + jump_label_lock(); + if (atomic_read(&key->enabled) == 0) { + atomic_set(&key->enabled, -1); +@@ -133,12 +135,14 @@ void static_key_slow_inc(struct static_key *key) + atomic_inc(&key->enabled); + } + jump_label_unlock(); ++ cpus_read_unlock(); + } + EXPORT_SYMBOL_GPL(static_key_slow_inc); + + static void __static_key_slow_dec(struct static_key *key, + unsigned long rate_limit, struct delayed_work *work) + { ++ cpus_read_lock(); + /* + * The negative count check is valid even when a negative + * key->enabled is in use by static_key_slow_inc(); a +@@ -149,6 +153,7 @@ static void __static_key_slow_dec(struct static_key *key, + if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) { + WARN(atomic_read(&key->enabled) < 0, + "jump label: negative count!\n"); ++ cpus_read_unlock(); + return; + } + +@@ -159,6 +164,7 @@ static void __static_key_slow_dec(struct static_key *key, + jump_label_update(key); + } + jump_label_unlock(); ++ cpus_read_unlock(); + } + + static void jump_label_update_timeout(struct work_struct *work) +@@ -334,6 +340,7 @@ void __init jump_label_init(void) + if (static_key_initialized) + return; + ++ cpus_read_lock(); + jump_label_lock(); + jump_label_sort_entries(iter_start, iter_stop); + +@@ -353,6 +360,7 @@ void __init jump_label_init(void) + } + static_key_initialized = true; + jump_label_unlock(); ++ cpus_read_unlock(); + } + + #ifdef CONFIG_MODULES +@@ -590,28 +598,28 @@ jump_label_module_notify(struct notifier_block *self, unsigned long val, + struct module *mod = data; + int ret = 0; + ++ cpus_read_lock(); ++ jump_label_lock(); ++ + switch (val) { + case MODULE_STATE_COMING: +- jump_label_lock(); + ret = jump_label_add_module(mod); + if (ret) { + WARN(1, "Failed to allocatote memory: jump_label may not work properly.\n"); + jump_label_del_module(mod); + } +- jump_label_unlock(); + break; + case MODULE_STATE_GOING: +- jump_label_lock(); + jump_label_del_module(mod); +- jump_label_unlock(); + break; + case MODULE_STATE_LIVE: +- jump_label_lock(); + jump_label_invalidate_module_init(mod); +- jump_label_unlock(); + break; + } + ++ jump_label_unlock(); ++ cpus_read_unlock(); ++ + return notifier_from_errno(ret); + } + +-- +2.11.0 + |