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| author | Takashi Iwai <tiwai@suse.de> | 2019-04-16 18:18:47 +0200 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2019-04-17 07:16:15 +0200 |
| commit | f4fa968950aef7efb98a0899bb0132405e2edaf1 (patch) | |
| tree | 2053bcf32985ef7539b02f10246bf67c4543903a /sound/core/sound.c | |
| parent | c989954938761a2939a21fcbc768af182de6be58 (diff) | |
| download | linux-f4fa968950aef7efb98a0899bb0132405e2edaf1.tar.bz2 | |
ALSA: core: Don't refer to snd_cards array directly
The snd_cards[] array holds the card pointers that have been currently
registered, and it's exported for the external modules that may need
to refer a card object. But accessing to this array can be racy
against the driver probe or removal, as the card registration or free
may happen concurrently.
This patch gets rid of the direct access to snd_cards[] array and
provides a helper function to give the card object from the index
number with a refcount management. Then the caller can access to the
given card object safely, and releases it via snd_card_unref().
While we're at it, add a proper comment to snd_card_unref() and make
it an inlined function for type-safety, too.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/core/sound.c')
| -rw-r--r-- | sound/core/sound.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/sound/core/sound.c b/sound/core/sound.c index b30f027eb0fe..a9ad4379523b 100644 --- a/sound/core/sound.c +++ b/sound/core/sound.c @@ -134,8 +134,11 @@ static struct snd_minor *autoload_device(unsigned int minor) if (dev == SNDRV_MINOR_CONTROL) { /* /dev/aloadC? */ int card = SNDRV_MINOR_CARD(minor); - if (snd_cards[card] == NULL) + struct snd_card *ref = snd_card_ref(card); + if (!ref) snd_request_card(card); + else + snd_card_unref(ref); } else if (dev == SNDRV_MINOR_GLOBAL) { /* /dev/aloadSEQ */ snd_request_other(minor); |