[PATCH AUTOSEL 5.18 30/39] ALSA: timer: Use deferred fasync helper

Sasha Levin
2022-08-14T16:33:44Z

From: Takashi Iwai <tiwai@suse.de>

[ Upstream commit 95cc637c1afd83fb7dd3d7c8a53710488f4caf9c ]

For avoiding the potential deadlock via kill_fasync() call, use the
new fasync helpers to defer the invocation from PCI API. Note that
it's merely a workaround.

Reported-by: syzbot+1ee0910eca9c94f71f25@syzkaller.appspotmail.com
Reported-by: syzbot+49b10793b867871ee26f@syzkaller.appspotmail.com
Reported-by: syzbot+8285e973a41b5aa68902@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20220728125945.29533-3-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
sound/core/timer.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/sound/core/timer.c b/sound/core/timer.c
index b3214baa8919..e08a37c23add 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -83,7 +83,7 @@ struct snd_timer_user {
unsigned int filter;
struct timespec64 tstamp; /* trigger tstamp */
wait_queue_head_t qchange_sleep;
- struct fasync_struct *fasync;
+ struct snd_fasync *fasync;
struct mutex ioctl_lock;
};

@@ -1345,7 +1345,7 @@ static void snd_timer_user_interrupt(struct snd_timer_instance *timeri,
}
__wake:
spin_unlock(&tu->qlock);
- kill_fasync(&tu->fasync, SIGIO, POLL_IN);
+ snd_kill_fasync(tu->fasync, SIGIO, POLL_IN);
wake_up(&tu->qchange_sleep);
}

@@ -1383,7 +1383,7 @@ static void snd_timer_user_ccallback(struct snd_timer_instance *timeri,
spin_lock_irqsave(&tu->qlock, flags);
snd_timer_user_append_to_tqueue(tu, &r1);
spin_unlock_irqrestore(&tu->qlock, flags);
- kill_fasync(&tu->fasync, SIGIO, POLL_IN);
+ snd_kill_fasync(tu->fasync, SIGIO, POLL_IN);
wake_up(&tu->qchange_sleep);
}

@@ -1453,7 +1453,7 @@ static void snd_timer_user_tinterrupt(struct snd_timer_instance *timeri,
spin_unlock(&tu->qlock);
if (append == 0)
return;
- kill_fasync(&tu->fasync, SIGIO, POLL_IN);
+ snd_kill_fasync(tu->fasync, SIGIO, POLL_IN);
wake_up(&tu->qchange_sleep);
}

@@ -1521,6 +1521,7 @@ static int snd_timer_user_release(struct inode *inode, struct file *file)
snd_timer_instance_free(tu->timeri);
}
mutex_unlock(&tu->ioctl_lock);
+ snd_fasync_free(tu->fasync);
kfree(tu->queue);
kfree(tu->tqueue);
kfree(tu);
@@ -2135,7 +2136,7 @@ static int snd_timer_user_fasync(int fd, struct file * file, int on)
struct snd_timer_user *tu;

tu = file->private_data;
- return fasync_helper(fd, file, on, &tu->fasync);
+ return snd_fasync_helper(fd, file, on, &tu->fasync);
}

static ssize_t snd_timer_user_read(struct file *file, char __user *buffer,
--
2.35.1