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signal: Split up __sigqueue_alloc()

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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.

Reorganize __sigqueue_alloc() so the ucounts retrieval and the
initialization can be used independently.

No functional change.

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/20241105064213.371410037@linutronix.de
This commit is contained in:
Thomas Gleixner 2024-11-05 09:14:38 +01:00
parent 5d916a0988
commit 5cac427f79
1 changed files with 35 additions and 17 deletions
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52
kernel/signal.c
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@ -396,16 +396,9 @@ void task_join_group_stop(struct task_struct *task)
task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING);
}
/*
* 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 gfp_flags,
int override_rlimit, const unsigned int sigqueue_flags)
static struct ucounts *sig_get_ucounts(struct task_struct *t, int sig,
int override_rlimit)
{
struct sigqueue *q = NULL;
struct ucounts *ucounts;
long sigpending;
@ -424,19 +417,44 @@ __sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags,
if (!sigpending)
return NULL;
if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
q = kmem_cache_alloc(sigqueue_cachep, gfp_flags);
} else {
if (unlikely(!override_rlimit && sigpending > task_rlimit(t, RLIMIT_SIGPENDING))) {
dec_rlimit_put_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
print_dropped_signal(sig);
return NULL;
}
if (unlikely(q == NULL)) {
return ucounts;
}
static void __sigqueue_init(struct sigqueue *q, struct ucounts *ucounts,
const unsigned int sigqueue_flags)
{
INIT_LIST_HEAD(&q->list);
q->flags = sigqueue_flags;
q->ucounts = ucounts;
}
/*
* 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 gfp_flags,
int override_rlimit, const unsigned int sigqueue_flags)
{
struct ucounts *ucounts = sig_get_ucounts(t, sig, override_rlimit);
struct sigqueue *q;
if (!ucounts)
return NULL;
q = kmem_cache_alloc(sigqueue_cachep, gfp_flags);
if (!q) {
dec_rlimit_put_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING);
} else {
INIT_LIST_HEAD(&q->list);
q->flags = sigqueue_flags;
q->ucounts = ucounts;
return NULL;
}
__sigqueue_init(q, ucounts, sigqueue_flags);
return q;
}