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posix-timers: Handle ignored list on delete and exit

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To handle posix timer signals on sigaction(SIG_IGN) properly, the timers
will be queued on a separate ignored list.

Add the necessary cleanup code for timer_delete() and exit_itimers().

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/20241105064213.987530588@linutronix.de
This commit is contained in:
Thomas Gleixner 2024-11-05 09:14:51 +01:00
parent 69f032c92c
commit 0e20cd33ac
2 changed files with 31 additions and 1 deletions
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4
include/linux/posix-timers.h
View File

@ -152,7 +152,8 @@ static inline void posix_cputimers_init_work(void) { }
/**
* struct k_itimer - POSIX.1b interval timer structure.
* @list: List head for binding the timer to signals->posix_timers
* @list: List node for binding the timer to tsk::signal::posix_timers
* @ignored_list: List node for tracking ignored timers in tsk::signal::ignored_posix_timers
* @t_hash: Entry in the posix timer hash table
* @it_lock: Lock protecting the timer
* @kclock: Pointer to the k_clock struct handling this timer
@ -176,6 +177,7 @@ static inline void posix_cputimers_init_work(void) { }
*/
struct k_itimer {
struct hlist_node list;
struct hlist_node ignored_list;
struct hlist_node t_hash;
spinlock_t it_lock;
const struct k_clock *kclock;

28
kernel/time/posix-timers.c
View File

@ -1027,6 +1027,18 @@ int common_timer_del(struct k_itimer *timer)
return 0;
}
/*
* If the deleted timer is on the ignored list, remove it and
* drop the associated reference.
*/
static inline void posix_timer_cleanup_ignored(struct k_itimer *tmr)
{
if (!hlist_unhashed(&tmr->ignored_list)) {
hlist_del_init(&tmr->ignored_list);
posixtimer_putref(tmr);
}
}
static inline int timer_delete_hook(struct k_itimer *timer)
{
const struct k_clock *kc = timer->kclock;
@ -1059,6 +1071,7 @@ retry_delete:
spin_lock(&current->sighand->siglock);
hlist_del(&timer->list);
posix_timer_cleanup_ignored(timer);
spin_unlock(&current->sighand->siglock);
/*
* A concurrent lookup could check timer::it_signal lockless. It
@ -1110,6 +1123,8 @@ retry_delete:
}
hlist_del(&timer->list);
posix_timer_cleanup_ignored(timer);
/*
* Setting timer::it_signal to NULL is technically not required
* here as nothing can access the timer anymore legitimately via
@ -1142,6 +1157,19 @@ void exit_itimers(struct task_struct *tsk)
/* The timers are not longer accessible via tsk::signal */
while (!hlist_empty(&timers))
itimer_delete(hlist_entry(timers.first, struct k_itimer, list));
/*
* There should be no timers on the ignored list. itimer_delete() has
* mopped them up.
*/
if (!WARN_ON_ONCE(!hlist_empty(&tsk->signal->ignored_posix_timers)))
return;
hlist_move_list(&tsk->signal->ignored_posix_timers, &timers);
while (!hlist_empty(&timers)) {
posix_timer_cleanup_ignored(hlist_entry(timers.first, struct k_itimer,
ignored_list));
}
}
SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,