ALSA: timer: Wrap with spinlock for queue access (d7f910bf) · Commits · 戴 / test

For accessing the snd_timer_user queue indices, we take tu->qlock. But it's forgotten in a couple of places. The one in snd_timer_user_params() should be safe without the spinlock as the timer is already stopped. But it's better for consistency. The one in poll is just a read-out, so it's not inevitably needed, but it'd be good to make the result consistent, too. Tested-by:

Alexander Potapenko <glider@google.com> Signed-off-by:

Takashi Iwai <tiwai@suse.de>

sound/core/timer.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -1755,6 +1755,7 @@ static int snd_timer_user_params(struct file *file,
		if (err < 0)
		goto _end;
		}
		spin_lock_irq(&tu->qlock);
		tu->qhead = tu->qtail = tu->qused = 0;
		if (tu->timeri->flags & SNDRV_TIMER_IFLG_EARLY_EVENT) {
		if (tu->tread) {
		@@ -1775,6 +1776,7 @@ static int snd_timer_user_params(struct file *file,
		}
		tu->filter = params.filter;
		tu->ticks = params.ticks;
		spin_unlock_irq(&tu->qlock);
		err = 0;
		_end:
		if (copy_to_user(_params, &params, sizeof(params)))
		@@ -2022,10 +2024,12 @@ static unsigned int snd_timer_user_poll(struct file file, poll_table wait)
		poll_wait(file, &tu->qchange_sleep, wait);

		mask = 0;
		spin_lock_irq(&tu->qlock);
		if (tu->qused)
		mask \|= POLLIN \| POLLRDNORM;
		if (tu->disconnected)
		mask \|= POLLERR;
		spin_unlock_irq(&tu->qlock);

		return mask;
		}

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