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| author | Thomas Gleixner <tglx@linutronix.de> | 2024-11-05 09:14:45 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2024-11-07 02:14:44 +0100 |
| commit | 6017a158beb13b412e55a451379798aae5876514 (patch) | |
| tree | d04d88eb8bb2a9fb3d7cbd4ac1ff0b7eedf69697 /kernel/signal.c | |
| parent | 11629b9808e5900d675fd469d19932ea48060de3 (diff) | |
| download | linux-stable-6017a158beb13b412e55a451379798aae5876514.tar.gz linux-stable-6017a158beb13b412e55a451379798aae5876514.tar.bz2 linux-stable-6017a158beb13b412e55a451379798aae5876514.zip | |
posix-timers: Embed sigqueue in struct k_itimer
To cure the SIG_IGN handling for posix interval timers, the preallocated
sigqueue needs to be embedded into struct k_itimer to prevent life time
races of all sorts.
Now that the prerequisites are in place, embed the sigqueue into struct
k_itimer and fixup the relevant usage sites.
Aside of preparing for proper SIG_IGN handling, this spares an extra
allocation.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20241105064213.719695194@linutronix.de
Diffstat (limited to 'kernel/signal.c')
| -rw-r--r-- | kernel/signal.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index 0ddb5dd284aa..2d74cd5841ae 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -460,8 +460,10 @@ static struct sigqueue *__sigqueue_alloc(int sig, struct task_struct *t, gfp_t g static void __sigqueue_free(struct sigqueue *q) { - if (q->flags & SIGQUEUE_PREALLOC) + if (q->flags & SIGQUEUE_PREALLOC) { + posixtimer_sigqueue_putref(q); return; + } if (q->ucounts) { dec_rlimit_put_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING); q->ucounts = NULL; @@ -569,11 +571,11 @@ still_pending: copy_siginfo(info, &first->info); /* - * posix-timer signals are preallocated and freed when the - * timer goes away. Either directly or by clearing - * SIGQUEUE_PREALLOC so that the next delivery will free - * them. Spare the extra round through __sigqueue_free() - * which is ignoring preallocated signals. + * posix-timer signals are preallocated and freed when the last + * reference count is dropped in posixtimer_deliver_signal() or + * immediately on timer deletion when the signal is not pending. + * Spare the extra round through __sigqueue_free() which is + * ignoring preallocated signals. */ if (unlikely((first->flags & SIGQUEUE_PREALLOC) && (info->si_code == SI_TIMER))) *timer_sigq = first; @@ -1989,7 +1991,7 @@ static inline struct task_struct *posixtimer_get_target(struct k_itimer *tmr) int posixtimer_send_sigqueue(struct k_itimer *tmr) { - struct sigqueue *q = tmr->sigq; + struct sigqueue *q = &tmr->sigq; int sig = q->info.si_signo; struct task_struct *t; unsigned long flags; @@ -2020,9 +2022,12 @@ int posixtimer_send_sigqueue(struct k_itimer *tmr) ret = 0; if (unlikely(!list_empty(&q->list))) { + /* This holds a reference count already */ result = TRACE_SIGNAL_ALREADY_PENDING; goto out; } + + posixtimer_sigqueue_getref(q); posixtimer_queue_sigqueue(q, t, tmr->it_pid_type); result = TRACE_SIGNAL_DELIVERED; out: |