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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/last.c | |
| parent | c989954938761a2939a21fcbc768af182de6be58 (diff) | |
| download | linux-f4fa968950aef7efb98a0899bb0132405e2edaf1.tar.gz linux-f4fa968950aef7efb98a0899bb0132405e2edaf1.tar.bz2 linux-f4fa968950aef7efb98a0899bb0132405e2edaf1.zip | |
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/last.c')
| -rw-r--r-- | sound/last.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/sound/last.c b/sound/last.c index 43f222825038..4f5a624ab438 100644 --- a/sound/last.c +++ b/sound/last.c @@ -24,14 +24,18 @@ static int __init alsa_sound_last_init(void) { + struct snd_card *card; int idx, ok = 0; printk(KERN_INFO "ALSA device list:\n"); - for (idx = 0; idx < SNDRV_CARDS; idx++) - if (snd_cards[idx] != NULL) { - printk(KERN_INFO " #%i: %s\n", idx, snd_cards[idx]->longname); + for (idx = 0; idx < SNDRV_CARDS; idx++) { + card = snd_card_ref(idx); + if (card) { + printk(KERN_INFO " #%i: %s\n", idx, card->longname); + snd_card_unref(card); ok++; } + } if (ok == 0) printk(KERN_INFO " No soundcards found.\n"); return 0; |