2017-10-29 14:23:02 -04:00
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From a27178e05b7c332522df40904f27674e36ee3757 Mon Sep 17 00:00:00 2001
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2017-10-29 01:48:53 -04:00
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From: Takashi Iwai <tiwai@suse.de>
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2017-10-29 14:23:02 -04:00
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Date: Mon, 12 Dec 2016 17:33:06 +0100
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2017-10-29 01:48:53 -04:00
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Subject: ALSA: pcm : Call kill_fasync() in stream lock
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2017-10-29 14:23:02 -04:00
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commit 3aa02cb664c5fb1042958c8d1aa8c35055a2ebc4 upstream.
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2017-10-29 01:48:53 -04:00
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Currently kill_fasync() is called outside the stream lock in
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snd_pcm_period_elapsed(). This is potentially racy, since the stream
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may get released even during the irq handler is running. Although
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snd_pcm_release_substream() calls snd_pcm_drop(), this doesn't
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guarantee that the irq handler finishes, thus the kill_fasync() call
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outside the stream spin lock may be invoked after the substream is
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detached, as recently reported by KASAN.
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As a quick workaround, move kill_fasync() call inside the stream
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lock. The fasync is rarely used interface, so this shouldn't have a
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big impact from the performance POV.
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Ideally, we should implement some sync mechanism for the proper finish
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of stream and irq handler. But this oneliner should suffice for most
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cases, so far.
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Reported-by: Baozeng Ding <sploving1@gmail.com>
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Signed-off-by: Takashi Iwai <tiwai@suse.de>
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2017-10-29 14:23:02 -04:00
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Signed-off-by: Willy Tarreau <w@1wt.eu>
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2017-10-29 01:48:53 -04:00
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---
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sound/core/pcm_lib.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
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2017-10-29 14:23:02 -04:00
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index 8eddece..dfed3ef 100644
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2017-10-29 01:48:53 -04:00
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--- a/sound/core/pcm_lib.c
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+++ b/sound/core/pcm_lib.c
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2017-10-29 14:23:02 -04:00
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@@ -1856,10 +1856,10 @@ void snd_pcm_period_elapsed(struct snd_pcm_substream *substream)
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if (substream->timer_running)
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2017-10-29 01:48:53 -04:00
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snd_timer_interrupt(substream->timer, 1);
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_end:
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2017-10-29 14:23:02 -04:00
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+ kill_fasync(&runtime->fasync, SIGIO, POLL_IN);
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snd_pcm_stream_unlock_irqrestore(substream, flags);
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if (runtime->transfer_ack_end)
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runtime->transfer_ack_end(substream);
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- kill_fasync(&runtime->fasync, SIGIO, POLL_IN);
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2017-10-29 01:48:53 -04:00
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}
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EXPORT_SYMBOL(snd_pcm_period_elapsed);
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--
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cgit v1.1
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