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authorTakashi Iwai <tiwai@suse.de>2008-09-25 14:51:03 +0200
committerTakashi Iwai <tiwai@suse.de>2008-09-25 14:51:03 +0200
commit399ccdc1cd4e92e541d4dacbbf18c52bd693418b (patch)
tree4e9ecc896adb79397166c02bdd4cedd690a54a98
parentb0b8daf7849cc98217ca018fbe82c61cd2b735bc (diff)
downloadlinux-linaro-399ccdc1cd4e92e541d4dacbbf18c52bd693418b.tar.gz
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>
-rw-r--r--sound/core/pcm.c4
-rw-r--r--sound/core/rawmidi.c4
2 files changed, 4 insertions, 4 deletions
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 9dd9bc73fe1..ece25c718e9 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:
diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c
index f7ea7287c59..b917a9f981c 100644
--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -418,7 +418,7 @@ static int snd_rawmidi_open(struct inode *inode, struct file *file)
mutex_lock(&rmidi->open_mutex);
while (1) {
subdevice = -1;
- 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) {
subdevice = kctl->prefer_rawmidi_subdevice;
@@ -426,7 +426,7 @@ static int snd_rawmidi_open(struct inode *inode, struct file *file)
break;
}
}
- up_read(&card->controls_rwsem);
+ read_unlock(&card->ctl_files_rwlock);
err = snd_rawmidi_kernel_open(rmidi->card, rmidi->device,
subdevice, fflags, rawmidi_file);
if (err >= 0)