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ALSA: hda: ext: fix locking in stream_release 

The snd_hdac_ext_stream_release() routine uses the bus reg_lock, but
releases it before calling snd_hdac_stream_release() where the bus
reg_lock is taken again.

This creates a timing window where the link stream release could test
an invalid 'opened' boolean status and fail to recouple the host and
link parts.

Fix by exposing a locked version of snd_hdac_stream_release() and use
it without releasing the spinlock.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20220919121041.43463-8-pierre-louis.bossart@linux.intel.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Pierre-Louis Bossart 2022-09-19 14:10:40 +02:00 committed by Takashi Iwai
parent 53f4f6b4e5
commit ac3467ad7f
3 changed files with 18 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/sound/hdaudio.h
View File

@ -551,6 +551,7 @@ void snd_hdac_stream_init(struct hdac_bus *bus, struct hdac_stream *azx_dev,
int idx, int direction, int tag);
struct hdac_stream *snd_hdac_stream_assign(struct hdac_bus *bus,
struct snd_pcm_substream *substream);
void snd_hdac_stream_release_locked(struct hdac_stream *azx_dev);
void snd_hdac_stream_release(struct hdac_stream *azx_dev);
struct hdac_stream *snd_hdac_get_stream(struct hdac_bus *bus,
int dir, int stream_tag);

2
sound/hda/ext/hdac_ext_stream.c
View File

@ -384,8 +384,8 @@ void snd_hdac_ext_stream_release(struct hdac_ext_stream *hext_stream, int type)
spin_lock_irq(&bus->reg_lock);
if (hext_stream->decoupled && !hext_stream->link_locked)
snd_hdac_ext_stream_decouple_locked(bus, hext_stream, false);
snd_hdac_stream_release_locked(&hext_stream->hstream);
spin_unlock_irq(&bus->reg_lock);
snd_hdac_stream_release(&hext_stream->hstream);
break;
case HDAC_EXT_STREAM_TYPE_LINK:

19
sound/hda/hdac_stream.c
View File

@ -365,6 +365,21 @@ struct hdac_stream *snd_hdac_stream_assign(struct hdac_bus *bus,
}
EXPORT_SYMBOL_GPL(snd_hdac_stream_assign);
/**
* snd_hdac_stream_release_locked - release the assigned stream
* @azx_dev: HD-audio core stream to release
*
* Release the stream that has been assigned by snd_hdac_stream_assign().
* The bus->reg_lock needs to be taken at a higher level
*/
void snd_hdac_stream_release_locked(struct hdac_stream *azx_dev)
{
azx_dev->opened = 0;
azx_dev->running = 0;
azx_dev->substream = NULL;
}
EXPORT_SYMBOL_GPL(snd_hdac_stream_release_locked);
/**
* snd_hdac_stream_release - release the assigned stream
* @azx_dev: HD-audio core stream to release
@ -376,9 +391,7 @@ void snd_hdac_stream_release(struct hdac_stream *azx_dev)
struct hdac_bus *bus = azx_dev->bus;
spin_lock_irq(&bus->reg_lock);
azx_dev->opened = 0;
azx_dev->running = 0;
azx_dev->substream = NULL;
snd_hdac_stream_release_locked(azx_dev);
spin_unlock_irq(&bus->reg_lock);
}
EXPORT_SYMBOL_GPL(snd_hdac_stream_release);