diff options
| -rw-r--r-- | include/linux/sched/signal.h | 2 | ||||
| -rw-r--r-- | kernel/signal.c | 10 | ||||
| -rw-r--r-- | kernel/time/posix-timers.c | 15 |
3 files changed, 11 insertions, 16 deletions
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index c8ed09ac29ac..bd9f569231d9 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -340,7 +340,7 @@ extern int send_sig(int, struct task_struct *, int); extern int zap_other_threads(struct task_struct *p); extern struct sigqueue *sigqueue_alloc(void); extern void sigqueue_free(struct sigqueue *); -extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type); +extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type, int si_private); extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *); static inline void clear_notify_signal(void) diff --git a/kernel/signal.c b/kernel/signal.c index f420c430b24a..1563c83ff224 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1919,7 +1919,7 @@ void sigqueue_free(struct sigqueue *q) __sigqueue_free(q); } -int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type) +int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type, int si_private) { int sig = q->info.si_signo; struct sigpending *pending; @@ -1954,6 +1954,14 @@ int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type) if (!likely(lock_task_sighand(t, &flags))) goto ret; + /* + * Update @q::info::si_sys_private for posix timer signals with + * sighand locked to prevent a race against dequeue_signal() which + * decides based on si_sys_private whether to invoke + * posixtimer_rearm() or not. + */ + q->info.si_sys_private = si_private; + ret = 1; /* the signal is ignored */ result = TRACE_SIGNAL_IGNORED; if (!prepare_signal(sig, t, false)) diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c index d461a32b7260..05af074285fa 100644 --- a/kernel/time/posix-timers.c +++ b/kernel/time/posix-timers.c @@ -299,21 +299,8 @@ int posix_timer_queue_signal(struct k_itimer *timr) if (timr->it_interval) si_private = ++timr->it_requeue_pending; - /* - * FIXME: if ->sigq is queued we can race with - * dequeue_signal()->posixtimer_rearm(). - * - * If dequeue_signal() sees the "right" value of - * si_sys_private it calls posixtimer_rearm(). - * We re-queue ->sigq and drop ->it_lock(). - * posixtimer_rearm() locks the timer - * and re-schedules it while ->sigq is pending. - * Not really bad, but not that we want. - */ - timr->sigq->info.si_sys_private = si_private; - type = !(timr->it_sigev_notify & SIGEV_THREAD_ID) ? PIDTYPE_TGID : PIDTYPE_PID; - ret = send_sigqueue(timr->sigq, timr->it_pid, type); + ret = send_sigqueue(timr->sigq, timr->it_pid, type, si_private); /* If we failed to send the signal the timer stops. */ return ret > 0; } |