diff options
author | Thomas Gleixner <tglx@linutronix.de> | 2009-07-03 13:44:56 (GMT) |
---|---|---|
committer | Scott Wood <scottwood@freescale.com> | 2014-04-10 00:18:37 (GMT) |
commit | 4fc142158128b576d5d598de0ee31b61c1a93ae0 (patch) | |
tree | 08067fdeb3f74681cdee7e3906e8d4dd07994e8e | |
parent | b0101260ebd73bf052ad4870417f363fc3e0dd70 (diff) | |
download | linux-fsl-qoriq-4fc142158128b576d5d598de0ee31b61c1a93ae0.tar.xz |
signals: Allow rt tasks to cache one sigqueue struct
To avoid allocation allow rt tasks to cache one sigqueue struct in
task struct.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r-- | include/linux/sched.h | 1 | ||||
-rw-r--r-- | include/linux/signal.h | 1 | ||||
-rw-r--r-- | kernel/exit.c | 2 | ||||
-rw-r--r-- | kernel/fork.c | 1 | ||||
-rw-r--r-- | kernel/signal.c | 84 |
5 files changed, 84 insertions, 5 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 230094d..4d58a49 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1204,6 +1204,7 @@ struct task_struct { /* signal handlers */ struct signal_struct *signal; struct sighand_struct *sighand; + struct sigqueue *sigqueue_cache; sigset_t blocked, real_blocked; sigset_t saved_sigmask; /* restored if set_restore_sigmask() was used */ diff --git a/include/linux/signal.h b/include/linux/signal.h index 2ac423b..1414eb2 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -226,6 +226,7 @@ static inline void init_sigpending(struct sigpending *sig) } 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) diff --git a/kernel/exit.c b/kernel/exit.c index a949819..7493b32 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -145,7 +145,7 @@ static void __exit_signal(struct task_struct *tsk) * 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); diff --git a/kernel/fork.c b/kernel/fork.c index 2bc18dd..c0174b8 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1235,6 +1235,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, spin_lock_init(&p->alloc_lock); init_sigpending(&p->pending); + p->sigqueue_cache = NULL; p->utime = p->stime = p->gtime = 0; p->utimescaled = p->stimescaled = 0; diff --git a/kernel/signal.c b/kernel/signal.c index 8ed7287..ed06b65 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -14,6 +14,7 @@ #include <linux/export.h> #include <linux/init.h> #include <linux/sched.h> +#include <linux/sched/rt.h> #include <linux/fs.h> #include <linux/tty.h> #include <linux/binfmts.h> @@ -349,13 +350,45 @@ static bool task_participate_group_stop(struct task_struct *task) return false; } +#ifdef __HAVE_ARCH_CMPXCHG +static inline struct sigqueue *get_task_cache(struct task_struct *t) +{ + struct sigqueue *q = t->sigqueue_cache; + + if (cmpxchg(&t->sigqueue_cache, q, NULL) != q) + return NULL; + return q; +} + +static inline int put_task_cache(struct task_struct *t, struct sigqueue *q) +{ + if (cmpxchg(&t->sigqueue_cache, NULL, q) == NULL) + return 0; + return 1; +} + +#else + +static inline struct sigqueue *get_task_cache(struct task_struct *t) +{ + return NULL; +} + +static inline int put_task_cache(struct task_struct *t, struct sigqueue *q) +{ + return 1; +} + +#endif + /* * 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, int fromslab) { struct sigqueue *q = NULL; struct user_struct *user; @@ -372,7 +405,10 @@ __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimi if (override_rlimit || atomic_read(&user->sigpending) <= task_rlimit(t, RLIMIT_SIGPENDING)) { - q = kmem_cache_alloc(sigqueue_cachep, flags); + if (!fromslab) + q = get_task_cache(t); + if (!q) + q = kmem_cache_alloc(sigqueue_cachep, flags); } else { print_dropped_signal(sig); } @@ -389,6 +425,13 @@ __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimi 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, 0); +} + static void __sigqueue_free(struct sigqueue *q) { if (q->flags & SIGQUEUE_PREALLOC) @@ -398,6 +441,21 @@ static void __sigqueue_free(struct sigqueue *q) kmem_cache_free(sigqueue_cachep, q); } +static void sigqueue_free_current(struct sigqueue *q) +{ + struct user_struct *up; + + if (q->flags & SIGQUEUE_PREALLOC) + return; + + up = q->user; + if (rt_prio(current->normal_prio) && !put_task_cache(current, q)) { + atomic_dec(&up->sigpending); + free_uid(up); + } else + __sigqueue_free(q); +} + void flush_sigqueue(struct sigpending *queue) { struct sigqueue *q; @@ -411,6 +469,21 @@ void flush_sigqueue(struct sigpending *queue) } /* + * 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 = get_task_cache(tsk); + if (q) + kmem_cache_free(sigqueue_cachep, q); +} + +/* * Flush all pending signals for a task. */ void __flush_signals(struct task_struct *t) @@ -562,7 +635,7 @@ static void collect_signal(int sig, struct sigpending *list, siginfo_t *info) still_pending: list_del_init(&first->list); copy_siginfo(info, &first->info); - __sigqueue_free(first); + sigqueue_free_current(first); } else { /* * Ok, it wasn't in the queue. This must be @@ -608,6 +681,8 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info) { int signr; + WARN_ON_ONCE(tsk != current); + /* We only dequeue private signals from ourselves, we don't let * signalfd steal them */ @@ -1547,7 +1622,8 @@ EXPORT_SYMBOL(kill_pid); */ struct sigqueue *sigqueue_alloc(void) { - struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0); + /* Preallocated sigqueue objects always from the slabcache ! */ + struct sigqueue *q = __sigqueue_do_alloc(-1, current, GFP_KERNEL, 0, 1); if (q) q->flags |= SIGQUEUE_PREALLOC; |