Merge branches 'timers/clocksource', 'timers/hrtimers', 'timers/nohz', 'timers/ntp', 'timers/posixtimers' and 'timers/debug' into v28-timers-for-linus

kernel/posix-timers.c

@@ -313,6 +313,7 @@ void do_schedule_next_timer(struct siginfo *info)
 
 int posix_timer_event(struct k_itimer *timr, int si_private)
 {
+	int shared, ret;
 	/*
 	 * FIXME: if ->sigq is queued we can race with
 	 * dequeue_signal()->do_schedule_next_timer().
@@ -326,25 +327,10 @@ int posix_timer_event(struct k_itimer *timr, int si_private)
 	 */
 	timr->sigq->info.si_sys_private = si_private;
 
-	timr->sigq->info.si_signo = timr->it_sigev_signo;
-	timr->sigq->info.si_code = SI_TIMER;
-	timr->sigq->info.si_tid = timr->it_id;
-	timr->sigq->info.si_value = timr->it_sigev_value;
-
-	if (timr->it_sigev_notify & SIGEV_THREAD_ID) {
-		struct task_struct *leader;
-		int ret = send_sigqueue(timr->sigq, timr->it_process, 0);
-
-		if (likely(ret >= 0))
-			return ret;
-
-		timr->it_sigev_notify = SIGEV_SIGNAL;
-		leader = timr->it_process->group_leader;
-		put_task_struct(timr->it_process);
-		timr->it_process = leader;
-	}
-
-	return send_sigqueue(timr->sigq, timr->it_process, 1);
+	shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID);
+	ret = send_sigqueue(timr->sigq, timr->it_process, shared);
+	/* If we failed to send the signal the timer stops. */
+	return ret > 0;
 }
 EXPORT_SYMBOL_GPL(posix_timer_event);
 
@@ -456,7 +442,7 @@ static struct k_itimer * alloc_posix_timer(void)
 		return tmr;
 	if (unlikely(!(tmr->sigq = sigqueue_alloc()))) {
 		kmem_cache_free(posix_timers_cache, tmr);
-		tmr = NULL;
+		return NULL;
 	}
 	memset(&tmr->sigq->info, 0, sizeof(siginfo_t));
 	return tmr;
@@ -483,11 +469,9 @@ sys_timer_create(const clockid_t which_clock,
 		 struct sigevent __user *timer_event_spec,
 		 timer_t __user * created_timer_id)
 {
-	int error = 0;
-	struct k_itimer *new_timer = NULL;
-	int new_timer_id;
-	struct task_struct *process = NULL;
-	unsigned long flags;
+	struct k_itimer *new_timer;
+	int error, new_timer_id;
+	struct task_struct *process;
 	sigevent_t event;
 	int it_id_set = IT_ID_NOT_SET;
 
@@ -505,12 +489,11 @@ sys_timer_create(const clockid_t which_clock,
 		goto out;
 	}
 	spin_lock_irq(&idr_lock);
-	error = idr_get_new(&posix_timers_id, (void *) new_timer,
-			    &new_timer_id);
+	error = idr_get_new(&posix_timers_id, new_timer, &new_timer_id);
 	spin_unlock_irq(&idr_lock);
-	if (error == -EAGAIN)
-		goto retry;
-	else if (error) {
+	if (error) {
+		if (error == -EAGAIN)
+			goto retry;
 		/*
 		 * Weird looking, but we return EAGAIN if the IDR is
 		 * full (proper POSIX return value for this)
@@ -541,67 +524,43 @@ sys_timer_create(const clockid_t which_clock,
 			error = -EFAULT;
 			goto out;
 		}
-		new_timer->it_sigev_notify = event.sigev_notify;
-		new_timer->it_sigev_signo = event.sigev_signo;
-		new_timer->it_sigev_value = event.sigev_value;
-
-		read_lock(&tasklist_lock);
-		if ((process = good_sigevent(&event))) {
-			/*
-			 * We may be setting up this process for another
-			 * thread.  It may be exiting.  To catch this
-			 * case the we check the PF_EXITING flag.  If
-			 * the flag is not set, the siglock will catch
-			 * him before it is too late (in exit_itimers).
-			 *
-			 * The exec case is a bit more invloved but easy
-			 * to code.  If the process is in our thread
-			 * group (and it must be or we would not allow
-			 * it here) and is doing an exec, it will cause
-			 * us to be killed.  In this case it will wait
-			 * for us to die which means we can finish this
-			 * linkage with our last gasp. I.e. no code :)
-			 */
-			spin_lock_irqsave(&process->sighand->siglock, flags);
-			if (!(process->flags & PF_EXITING)) {
-				new_timer->it_process = process;
-				list_add(&new_timer->list,
-					 &process->signal->posix_timers);
-				if (new_timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
-					get_task_struct(process);
-				spin_unlock_irqrestore(&process->sighand->siglock, flags);
-			} else {
-				spin_unlock_irqrestore(&process->sighand->siglock, flags);
-				process = NULL;
-			}
-		}
-		read_unlock(&tasklist_lock);
+		rcu_read_lock();
+		process = good_sigevent(&event);
+		if (process)
+			get_task_struct(process);
+		rcu_read_unlock();
 		if (!process) {
 			error = -EINVAL;
 			goto out;
 		}
 	} else {
-		new_timer->it_sigev_notify = SIGEV_SIGNAL;
-		new_timer->it_sigev_signo = SIGALRM;
-		new_timer->it_sigev_value.sival_int = new_timer->it_id;
+		event.sigev_notify = SIGEV_SIGNAL;
+		event.sigev_signo = SIGALRM;
+		event.sigev_value.sival_int = new_timer->it_id;
 		process = current->group_leader;
-		spin_lock_irqsave(&process->sighand->siglock, flags);
-		new_timer->it_process = process;
-		list_add(&new_timer->list, &process->signal->posix_timers);
-		spin_unlock_irqrestore(&process->sighand->siglock, flags);
+		get_task_struct(process);
 	}
 
+	new_timer->it_sigev_notify     = event.sigev_notify;
+	new_timer->sigq->info.si_signo = event.sigev_signo;
+	new_timer->sigq->info.si_value = event.sigev_value;
+	new_timer->sigq->info.si_tid   = new_timer->it_id;
+	new_timer->sigq->info.si_code  = SI_TIMER;
+
+	spin_lock_irq(&current->sighand->siglock);
+	new_timer->it_process = process;
+	list_add(&new_timer->list, &current->signal->posix_timers);
+	spin_unlock_irq(&current->sighand->siglock);
+
+	return 0;
  	/*
 	 * In the case of the timer belonging to another task, after
 	 * the task is unlocked, the timer is owned by the other task
 	 * and may cease to exist at any time.  Don't use or modify
 	 * new_timer after the unlock call.
 	 */
-
 out:
-	if (error)
-		release_posix_timer(new_timer, it_id_set);
-
+	release_posix_timer(new_timer, it_id_set);
 	return error;
 }
 
@@ -612,7 +571,7 @@ out:
  * the find to the timer lock.  To avoid a dead lock, the timer id MUST
  * be release with out holding the timer lock.
  */
-static struct k_itimer * lock_timer(timer_t timer_id, unsigned long *flags)
+static struct k_itimer *lock_timer(timer_t timer_id, unsigned long *flags)
 {
 	struct k_itimer *timr;
 	/*
@@ -620,23 +579,20 @@ static struct k_itimer * lock_timer(timer_t timer_id, unsigned long *flags)
 	 * flags part over to the timer lock.  Must not let interrupts in
 	 * while we are moving the lock.
 	 */
-
 	spin_lock_irqsave(&idr_lock, *flags);
-	timr = (struct k_itimer *) idr_find(&posix_timers_id, (int) timer_id);
+	timr = idr_find(&posix_timers_id, (int)timer_id);
 	if (timr) {
 		spin_lock(&timr->it_lock);
-
-		if ((timr->it_id != timer_id) || !(timr->it_process) ||
-				!same_thread_group(timr->it_process, current)) {
-			spin_unlock(&timr->it_lock);
-			spin_unlock_irqrestore(&idr_lock, *flags);
-			timr = NULL;
-		} else
+		if (timr->it_process &&
+		    same_thread_group(timr->it_process, current)) {
 			spin_unlock(&idr_lock);
-	} else
-		spin_unlock_irqrestore(&idr_lock, *flags);
+			return timr;
+		}
+		spin_unlock(&timr->it_lock);
+	}
+	spin_unlock_irqrestore(&idr_lock, *flags);
 
-	return timr;
+	return NULL;
 }
 
 /*
@@ -877,8 +833,7 @@ retry_delete:
 	 * This keeps any tasks waiting on the spin lock from thinking
 	 * they got something (see the lock code above).
 	 */
-	if (timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
-		put_task_struct(timer->it_process);
+	put_task_struct(timer->it_process);
 	timer->it_process = NULL;
 
 	unlock_timer(timer, flags);
@@ -905,8 +860,7 @@ retry_delete:
 	 * This keeps any tasks waiting on the spin lock from thinking
 	 * they got something (see the lock code above).
 	 */
-	if (timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
-		put_task_struct(timer->it_process);
+	put_task_struct(timer->it_process);
 	timer->it_process = NULL;
 
 	unlock_timer(timer, flags);