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authorMichał Mirosław <mirq-linux@rere.qmqm.pl>2020-06-08 12:06:32 +0200
committerTakashi Iwai <tiwai@suse.de>2020-06-08 15:01:45 +0200
commite18035cf5cb3d2bf8e4f4d350a23608bd208b934 (patch)
tree447725e4df87724f1224303c774ca29e94ad8b76 /sound/core
parente4b0e41fee948ad327f9c912160aa4b50a6a4340 (diff)
ALSA: pcm: fix snd_pcm_link() lockdep splat
Add and use snd_pcm_stream_lock_nested() in snd_pcm_link/unlink implementation. The code is fine, but generates a lockdep complaint: ============================================ WARNING: possible recursive locking detected 5.7.1mq+ #381 Tainted: G O -------------------------------------------- pulseaudio/4180 is trying to acquire lock: ffff888402d6f508 (&group->lock){-...}-{2:2}, at: snd_pcm_common_ioctl+0xda8/0xee0 [snd_pcm] but task is already holding lock: ffff8883f7a8cf18 (&group->lock){-...}-{2:2}, at: snd_pcm_common_ioctl+0xe4e/0xee0 [snd_pcm] other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&group->lock); lock(&group->lock); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by pulseaudio/4180: #0: ffffffffa1a05190 (snd_pcm_link_rwsem){++++}-{3:3}, at: snd_pcm_common_ioctl+0xca0/0xee0 [snd_pcm] #1: ffff8883f7a8cf18 (&group->lock){-...}-{2:2}, at: snd_pcm_common_ioctl+0xe4e/0xee0 [snd_pcm] [...] Cc: stable@vger.kernel.org Fixes: f57f3df03a8e ("ALSA: pcm: More fine-grained PCM link locking") Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl> Link: https://lore.kernel.org/r/37252c65941e58473b1219ca9fab03d48f47e3e3.1591610330.git.mirq-linux@rere.qmqm.pl Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/core')
-rw-r--r--sound/core/pcm_native.c14
1 files changed, 12 insertions, 2 deletions
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index aef860256278..c08732998a42 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -138,6 +138,16 @@ void snd_pcm_stream_lock_irq(struct snd_pcm_substream *substream)
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_lock_irq);
+static void snd_pcm_stream_lock_nested(struct snd_pcm_substream *substream)
+{
+ struct snd_pcm_group *group = &substream->self_group;
+
+ if (substream->pcm->nonatomic)
+ mutex_lock_nested(&group->mutex, SINGLE_DEPTH_NESTING);
+ else
+ spin_lock_nested(&group->lock, SINGLE_DEPTH_NESTING);
+}
+
/**
* snd_pcm_stream_unlock_irq - Unlock the PCM stream
* @substream: PCM substream
@@ -2194,7 +2204,7 @@ static int snd_pcm_link(struct snd_pcm_substream *substream, int fd)
snd_pcm_stream_unlock_irq(substream);
snd_pcm_group_lock_irq(target_group, nonatomic);
- snd_pcm_stream_lock(substream1);
+ snd_pcm_stream_lock_nested(substream1);
snd_pcm_group_assign(substream1, target_group);
refcount_inc(&target_group->refs);
snd_pcm_stream_unlock(substream1);
@@ -2210,7 +2220,7 @@ static int snd_pcm_link(struct snd_pcm_substream *substream, int fd)
static void relink_to_local(struct snd_pcm_substream *substream)
{
- snd_pcm_stream_lock(substream);
+ snd_pcm_stream_lock_nested(substream);
snd_pcm_group_assign(substream, &substream->self_group);
snd_pcm_stream_unlock(substream);
}