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| author | Takashi Iwai <tiwai@suse.de> | 2008-09-25 16:51:03 +0400 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2008-09-25 16:51:03 +0400 |
| commit | 399ccdc1cd4e92e541d4dacbbf18c52bd693418b (patch) | |
| tree | 4e9ecc896adb79397166c02bdd4cedd690a54a98 /sound/core/pcm.c | |
| parent | b0b8daf7849cc98217ca018fbe82c61cd2b735bc (diff) | |
| download | linux-399ccdc1cd4e92e541d4dacbbf18c52bd693418b.tar.xz | |
ALSA: fix locking in snd_pcm_open*() and snd_rawmidi_open*()
The PCM and rawmidi open callbacks have a lock against card->controls_list
but it takes a wrong one, card->controls_rwsem, instead of a right one
card->ctl_files_rwlock. This patch fixes them.
This change also fixes automatically the potential deadlocks due to
mm->mmap_sem in munmap and copy_from/to_user, reported by Sitsofe
Wheeler:
A: snd_ctl_elem_user_tlv(): card->controls_rwsem => mm->mmap_sem
B: snd_pcm_open(): card->open_mutex => card->controls_rwsem
C: munmap: mm->mmap_sem => snd_pcm_release(): card->open_mutex
The patch breaks the chain.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/core/pcm.c')
| -rw-r--r-- | sound/core/pcm.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/sound/core/pcm.c b/sound/core/pcm.c index 9dd9bc73fe1d..ece25c718e95 100644 --- a/sound/core/pcm.c +++ b/sound/core/pcm.c @@ -781,7 +781,7 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream, return -ENODEV; card = pcm->card; - down_read(&card->controls_rwsem); + read_lock(&card->ctl_files_rwlock); list_for_each_entry(kctl, &card->ctl_files, list) { if (kctl->pid == current->pid) { prefer_subdevice = kctl->prefer_pcm_subdevice; @@ -789,7 +789,7 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream, break; } } - up_read(&card->controls_rwsem); + read_unlock(&card->ctl_files_rwlock); switch (stream) { case SNDRV_PCM_STREAM_PLAYBACK: |