Messages in this thread Patch in this message | | | From | Thomas Gleixner <> | Subject | [patch V2 47/50] signal: Queue ignored posixtimers on ignore list | Date | Thu, 11 Apr 2024 00:47:34 +0200 (CEST) |
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Queue posixtimers which have their signal ignored on the ignored list:
1) When the timer fires and the signal has SIG_IGN set
2) When SIG_IGN is installed via sigaction() and a timer signal is queued
This completes the SIG_IGN handling and such timers are not longer self rearmed which avoids pointless wakeups.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- kernel/signal.c | 44 ++++++++++++++++++++++++++++++++++++-------- 1 file changed, 36 insertions(+), 8 deletions(-)
--- a/kernel/signal.c +++ b/kernel/signal.c @@ -722,6 +722,16 @@ void signal_wake_up_state(struct task_st kick_process(t); } +static inline void posixtimer_sig_ignore(struct task_struct *tsk, struct sigqueue *q); + +static void sigqueue_free_ignored(struct task_struct *ptmr_tsk, struct sigqueue *q) +{ + if (likely(!ptmr_tsk || q->info.si_code != SI_TIMER)) + __sigqueue_free(q); + else + posixtimer_sig_ignore(ptmr_tsk, q); +} + /* * Remove signals in mask from the pending set and queue. * @@ -740,7 +750,7 @@ static void flush_sigqueue_mask(sigset_t list_for_each_entry_safe(q, n, &s->list, list) { if (sigismember(mask, q->info.si_signo)) { list_del_init(&q->list); - __sigqueue_free(q); + sigqueue_free_ignored(ptmr_tsk, q); } } } @@ -1964,9 +1974,8 @@ int posixtimer_send_sigqueue(struct k_it int sig = q->info.si_signo; struct task_struct *t; unsigned long flags; - int ret, result; + int result; - ret = -1; rcu_read_lock(); t = posixtimer_get_target(tmr); @@ -2012,13 +2021,24 @@ int posixtimer_send_sigqueue(struct k_it */ q->info.si_overrun = 0; - ret = 1; /* the signal is ignored */ if (!prepare_signal(sig, t, false)) { result = TRACE_SIGNAL_IGNORED; + + /* Paranoia check. Try to survive. */ + if (WARN_ON_ONCE(!list_empty(&q->list))) + goto out; + + if (hlist_unhashed(&tmr->ignored_list)) { + hlist_add_head(&tmr->ignored_list, &t->signal->ignored_posix_timers); + posixtimer_sigqueue_getref(q); + } goto out; } - ret = 0; + /* This should never happen and leaks a reference count */ + if (WARN_ON_ONCE(!hlist_unhashed(&tmr->ignored_list))) + hlist_del_init(&tmr->ignored_list); + if (unlikely(!list_empty(&q->list))) { /* This holds a reference count already */ result = TRACE_SIGNAL_ALREADY_PENDING; @@ -2033,7 +2053,14 @@ int posixtimer_send_sigqueue(struct k_it unlock_task_sighand(t, &flags); ret: rcu_read_unlock(); - return ret; + return 0; +} + +static inline void posixtimer_sig_ignore(struct task_struct *tsk, struct sigqueue *q) +{ + struct k_itimer *tmr = container_of(q, struct k_itimer, sigq); + + hlist_add_head(&tmr->ignored_list, &tsk->signal->ignored_posix_timers); } static void posixtimer_sig_unignore(struct task_struct *tsk, int sig) @@ -2082,6 +2109,7 @@ static void posixtimer_sig_unignore(stru } } #else /* CONFIG_POSIX_TIMERS */ +static inline void posixtimer_sig_ignore(struct task_struct *tsk, struct sigqueue *q) { } static inline void posixtimer_sig_unignore(struct task_struct *tsk, int sig) { } #endif /* !CONFIG_POSIX_TIMERS */ @@ -4272,9 +4300,9 @@ int do_sigaction(int sig, struct k_sigac if (sig_handler_ignored(sig_handler(p, sig), sig)) { sigemptyset(&mask); sigaddset(&mask, sig); - flush_sigqueue_mask(&mask, &p->signal->shared_pending, NULL); + flush_sigqueue_mask(&mask, &p->signal->shared_pending, p); for_each_thread(p, t) - flush_sigqueue_mask(&mask, &t->pending, NULL); + flush_sigqueue_mask(&mask, &t->pending, p); } else if (was_ignored) { posixtimer_sig_unignore(p, sig); }
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