snd_jack_report() is supposed to be callable from an IRQ context, too, and it's indeed used in that way from virtsnd driver. The fix for input_dev race in commit 1b6a6fc5280e ("ALSA: jack: Access input_dev under mutex"), however, introduced a mutex lock in snd_jack_report(), and this resulted in a potential sleep-in-atomic.
For addressing that problem, this patch changes the relevant code to use the object get/put and removes the mutex usage. That is, snd_jack_report(), it takes input_get_device() and leaves with input_put_device() for assuring the input_dev being assigned.
Although the whole mutex could be reduced, we keep it because it can be still a protection for potential races between creation and deletion.
Fixes: 1b6a6fc5280e ("ALSA: jack: Access input_dev under mutex") Reported-by: Dan Carpenter dan.carpenter@linaro.org Closes: https://lore.kernel.org/r/cf95f7fe-a748-4990-8378-000491b40329@moroto.mounta... Tested-by: Amadeusz Sławiński amadeuszx.slawinski@linux.intel.com Cc: stable@vger.kernel.org Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/core/jack.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/sound/core/jack.c b/sound/core/jack.c index 88493cc31914..03d155ed362b 100644 --- a/sound/core/jack.c +++ b/sound/core/jack.c @@ -654,6 +654,7 @@ void snd_jack_report(struct snd_jack *jack, int status) struct snd_jack_kctl *jack_kctl; unsigned int mask_bits = 0; #ifdef CONFIG_SND_JACK_INPUT_DEV + struct input_dev *idev; int i; #endif
@@ -670,17 +671,15 @@ void snd_jack_report(struct snd_jack *jack, int status) status & jack_kctl->mask_bits);
#ifdef CONFIG_SND_JACK_INPUT_DEV - mutex_lock(&jack->input_dev_lock); - if (!jack->input_dev) { - mutex_unlock(&jack->input_dev_lock); + idev = input_get_device(jack->input_dev); + if (!idev) return; - }
for (i = 0; i < ARRAY_SIZE(jack->key); i++) { int testbit = ((SND_JACK_BTN_0 >> i) & ~mask_bits);
if (jack->type & testbit) - input_report_key(jack->input_dev, jack->key[i], + input_report_key(idev, jack->key[i], status & testbit); }
@@ -688,13 +687,13 @@ void snd_jack_report(struct snd_jack *jack, int status) int testbit = ((1 << i) & ~mask_bits);
if (jack->type & testbit) - input_report_switch(jack->input_dev, + input_report_switch(idev, jack_switch_types[i], status & testbit); }
- input_sync(jack->input_dev); - mutex_unlock(&jack->input_dev_lock); + input_sync(idev); + input_put_device(idev); #endif /* CONFIG_SND_JACK_INPUT_DEV */ } EXPORT_SYMBOL(snd_jack_report);