From: Takashi Iwai tiwai@suse.de
stable inclusion from stable-v5.10.138 commit 857ccedcf569665809d351241d22247c6c55887f category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I60QFD
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
--------------------------------
[ Upstream commit 4a971e84a7ae10a38d875cd2d4e487c8d1682ca3 ]
For avoiding the potential deadlock via kill_fasync() call, use the new fasync helpers to defer the invocation from the control API. Note that it's merely a workaround.
Another note: although we haven't received reports about the deadlock with the control API, the deadlock is still potentially possible, and it's better to align the behavior with other core APIs (PCM and timer); so let's move altogether.
Link: https://lore.kernel.org/r/20220728125945.29533-5-tiwai@suse.de Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Reviewed-by: Wei Li liwei391@huawei.com --- include/sound/control.h | 2 +- sound/core/control.c | 7 ++++--- 2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/include/sound/control.h b/include/sound/control.h index 77d9fa10812d..41bd72ffd232 100644 --- a/include/sound/control.h +++ b/include/sound/control.h @@ -103,7 +103,7 @@ struct snd_ctl_file { int preferred_subdevice[SND_CTL_SUBDEV_ITEMS]; wait_queue_head_t change_sleep; spinlock_t read_lock; - struct fasync_struct *fasync; + struct snd_fasync *fasync; int subscribed; /* read interface is activated */ struct list_head events; /* waiting events for read */ }; diff --git a/sound/core/control.c b/sound/core/control.c index 3b44378b9dec..732eb515d2f5 100644 --- a/sound/core/control.c +++ b/sound/core/control.c @@ -121,6 +121,7 @@ static int snd_ctl_release(struct inode *inode, struct file *file) if (control->vd[idx].owner == ctl) control->vd[idx].owner = NULL; up_write(&card->controls_rwsem); + snd_fasync_free(ctl->fasync); snd_ctl_empty_read_queue(ctl); put_pid(ctl->pid); kfree(ctl); @@ -175,7 +176,7 @@ void snd_ctl_notify(struct snd_card *card, unsigned int mask, _found: wake_up(&ctl->change_sleep); spin_unlock(&ctl->read_lock); - kill_fasync(&ctl->fasync, SIGIO, POLL_IN); + snd_kill_fasync(ctl->fasync, SIGIO, POLL_IN); } read_unlock_irqrestore(&card->ctl_files_rwlock, flags); } @@ -1941,7 +1942,7 @@ static int snd_ctl_fasync(int fd, struct file * file, int on) struct snd_ctl_file *ctl;
ctl = file->private_data; - return fasync_helper(fd, file, on, &ctl->fasync); + return snd_fasync_helper(fd, file, on, &ctl->fasync); }
/* return the preferred subdevice number if already assigned; @@ -2015,7 +2016,7 @@ static int snd_ctl_dev_disconnect(struct snd_device *device) read_lock_irqsave(&card->ctl_files_rwlock, flags); list_for_each_entry(ctl, &card->ctl_files, list) { wake_up(&ctl->change_sleep); - kill_fasync(&ctl->fasync, SIGIO, POLL_ERR); + snd_kill_fasync(ctl->fasync, SIGIO, POLL_ERR); } read_unlock_irqrestore(&card->ctl_files_rwlock, flags);