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-rw-r--r--patches/signals-allow-rt-tasks-to-cache-one-sigqueue-struct.patch202
1 files changed, 0 insertions, 202 deletions
diff --git a/patches/signals-allow-rt-tasks-to-cache-one-sigqueue-struct.patch b/patches/signals-allow-rt-tasks-to-cache-one-sigqueue-struct.patch
deleted file mode 100644
index 478281b8f5f4..000000000000
--- a/patches/signals-allow-rt-tasks-to-cache-one-sigqueue-struct.patch
+++ /dev/null
@@ -1,202 +0,0 @@
-From: Thomas Gleixner <tglx@linutronix.de>
-Date: Fri, 3 Jul 2009 08:44:56 -0500
-Subject: signals: Allow RT tasks to cache one sigqueue struct
-
-Allow realtime tasks to cache one sigqueue in task struct. This avoids an
-allocation which can cause latencies or fail.
-Ideally the sigqueue is cached after first sucessfull delivery and will be
-available for next signal delivery. This works under the assumption that the RT
-task has never an unprocessed singal while one is about to be queued.
-The caching is not used for SIGQUEUE_PREALLOC because this kind of sigqueue is
-handled differently (and not used for regular signal delivery).
-
-[bigeasy: With a fix from Matt Fleming <matt@codeblueprint.co.uk>]
-Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
----
- include/linux/sched.h | 1
- include/linux/signal.h | 1
- kernel/exit.c | 2 -
- kernel/fork.c | 1
- kernel/signal.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++---
- 5 files changed, 67 insertions(+), 5 deletions(-)
-
---- a/include/linux/sched.h
-+++ b/include/linux/sched.h
-@@ -988,6 +988,7 @@ struct task_struct {
- /* Signal handlers: */
- struct signal_struct *signal;
- struct sighand_struct __rcu *sighand;
-+ struct sigqueue *sigqueue_cache;
- sigset_t blocked;
- sigset_t real_blocked;
- /* Restored if set_restore_sigmask() was used: */
---- a/include/linux/signal.h
-+++ b/include/linux/signal.h
-@@ -265,6 +265,7 @@ static inline void init_sigpending(struc
- }
-
- extern void flush_sigqueue(struct sigpending *queue);
-+extern void flush_task_sigqueue(struct task_struct *tsk);
-
- /* Test if 'sig' is valid signal. Use this instead of testing _NSIG directly */
- static inline int valid_signal(unsigned long sig)
---- a/kernel/exit.c
-+++ b/kernel/exit.c
-@@ -152,7 +152,7 @@ static void __exit_signal(struct task_st
- * Do this under ->siglock, we can race with another thread
- * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
- */
-- flush_sigqueue(&tsk->pending);
-+ flush_task_sigqueue(tsk);
- tsk->sighand = NULL;
- spin_unlock(&sighand->siglock);
-
---- a/kernel/fork.c
-+++ b/kernel/fork.c
-@@ -2027,6 +2027,7 @@ static __latent_entropy struct task_stru
- spin_lock_init(&p->alloc_lock);
-
- init_sigpending(&p->pending);
-+ p->sigqueue_cache = NULL;
-
- p->utime = p->stime = p->gtime = 0;
- #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
---- a/kernel/signal.c
-+++ b/kernel/signal.c
-@@ -20,6 +20,7 @@
- #include <linux/sched/task.h>
- #include <linux/sched/task_stack.h>
- #include <linux/sched/cputime.h>
-+#include <linux/sched/rt.h>
- #include <linux/file.h>
- #include <linux/fs.h>
- #include <linux/proc_fs.h>
-@@ -404,13 +405,30 @@ void task_join_group_stop(struct task_st
- task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING);
- }
-
-+static struct sigqueue *sigqueue_from_cache(struct task_struct *t)
-+{
-+ struct sigqueue *q = t->sigqueue_cache;
-+
-+ if (q && cmpxchg(&t->sigqueue_cache, q, NULL) == q)
-+ return q;
-+ return NULL;
-+}
-+
-+static bool sigqueue_add_cache(struct task_struct *t, struct sigqueue *q)
-+{
-+ if (!t->sigqueue_cache && cmpxchg(&t->sigqueue_cache, NULL, q) == NULL)
-+ return true;
-+ return false;
-+}
-+
- /*
- * allocate a new signal queue record
- * - this may be called without locks if and only if t == current, otherwise an
- * appropriate lock must be held to stop the target task from exiting
- */
- static struct sigqueue *
--__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
-+__sigqueue_do_alloc(int sig, struct task_struct *t, gfp_t flags,
-+ int override_rlimit, bool fromslab)
- {
- struct sigqueue *q = NULL;
- struct user_struct *user;
-@@ -432,7 +450,10 @@ static struct sigqueue *
- rcu_read_unlock();
-
- if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
-- q = kmem_cache_alloc(sigqueue_cachep, flags);
-+ if (!fromslab)
-+ q = sigqueue_from_cache(t);
-+ if (!q)
-+ q = kmem_cache_alloc(sigqueue_cachep, flags);
- } else {
- print_dropped_signal(sig);
- }
-@@ -449,6 +470,13 @@ static struct sigqueue *
- return q;
- }
-
-+static struct sigqueue *
-+__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags,
-+ int override_rlimit)
-+{
-+ return __sigqueue_do_alloc(sig, t, flags, override_rlimit, false);
-+}
-+
- static void __sigqueue_free(struct sigqueue *q)
- {
- if (q->flags & SIGQUEUE_PREALLOC)
-@@ -458,6 +486,20 @@ static void __sigqueue_free(struct sigqu
- kmem_cache_free(sigqueue_cachep, q);
- }
-
-+static void __sigqueue_cache_or_free(struct sigqueue *q)
-+{
-+ struct user_struct *up;
-+
-+ if (q->flags & SIGQUEUE_PREALLOC)
-+ return;
-+
-+ up = q->user;
-+ if (atomic_dec_and_test(&up->sigpending))
-+ free_uid(up);
-+ if (!task_is_realtime(current) || !sigqueue_add_cache(current, q))
-+ kmem_cache_free(sigqueue_cachep, q);
-+}
-+
- void flush_sigqueue(struct sigpending *queue)
- {
- struct sigqueue *q;
-@@ -471,6 +513,21 @@ void flush_sigqueue(struct sigpending *q
- }
-
- /*
-+ * Called from __exit_signal. Flush tsk->pending and
-+ * tsk->sigqueue_cache
-+ */
-+void flush_task_sigqueue(struct task_struct *tsk)
-+{
-+ struct sigqueue *q;
-+
-+ flush_sigqueue(&tsk->pending);
-+
-+ q = sigqueue_from_cache(tsk);
-+ if (q)
-+ kmem_cache_free(sigqueue_cachep, q);
-+}
-+
-+/*
- * Flush all pending signals for this kthread.
- */
- void flush_signals(struct task_struct *t)
-@@ -594,7 +651,7 @@ static void collect_signal(int sig, stru
- (info->si_code == SI_TIMER) &&
- (info->si_sys_private);
-
-- __sigqueue_free(first);
-+ __sigqueue_cache_or_free(first);
- } else {
- /*
- * Ok, it wasn't in the queue. This must be
-@@ -631,6 +688,8 @@ int dequeue_signal(struct task_struct *t
- bool resched_timer = false;
- int signr;
-
-+ WARN_ON_ONCE(tsk != current);
-+
- /* We only dequeue private signals from ourselves, we don't let
- * signalfd steal them
- */
-@@ -1835,7 +1894,7 @@ EXPORT_SYMBOL(kill_pid);
- */
- struct sigqueue *sigqueue_alloc(void)
- {
-- struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
-+ struct sigqueue *q = __sigqueue_do_alloc(-1, current, GFP_KERNEL, 0, true);
-
- if (q)
- q->flags |= SIGQUEUE_PREALLOC;
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