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ALSA: usb-audio: Fix deadlocks at resuming

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The recent addition of the USB audio mixer suspend/resume may lead to
deadlocks when the driver tries to call usb_autopm_get_interface()
recursively, since the function tries to sync with the finish of the
other calls.  For avoiding it, introduce a flag indicating the resume
operation and avoids the recursive usb_autopm_get_interface() calls
during the resume.

Reported-and-tested-by: Bryan Quigley <gquigs@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2014-05-02 18:17:06 +02:00
parent 1c53e7253e
commit 1ee23fe07e
2 changed files with 6 additions and 2 deletions
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7
sound/usb/card.c
View File

@ -651,7 +651,7 @@ int snd_usb_autoresume(struct snd_usb_audio *chip)
int err = -ENODEV;
down_read(&chip->shutdown_rwsem);
if (chip->probing)
if (chip->probing && chip->in_pm)
err = 0;
else if (!chip->shutdown)
err = usb_autopm_get_interface(chip->pm_intf);
@ -663,7 +663,7 @@ int snd_usb_autoresume(struct snd_usb_audio *chip)
void snd_usb_autosuspend(struct snd_usb_audio *chip)
{
down_read(&chip->shutdown_rwsem);
if (!chip->shutdown && !chip->probing)
if (!chip->shutdown && !chip->probing && !chip->in_pm)
usb_autopm_put_interface(chip->pm_intf);
up_read(&chip->shutdown_rwsem);
}
@ -712,6 +712,8 @@ static int __usb_audio_resume(struct usb_interface *intf, bool reset_resume)
return 0;
if (--chip->num_suspended_intf)
return 0;
chip->in_pm = 1;
/*
* ALSA leaves material resumption to user space
* we just notify and restart the mixers
@ -727,6 +729,7 @@ static int __usb_audio_resume(struct usb_interface *intf, bool reset_resume)
chip->autosuspended = 0;
err_out:
chip->in_pm = 0;
return err;
}

1
sound/usb/usbaudio.h
View File

@ -40,6 +40,7 @@ struct snd_usb_audio {
struct rw_semaphore shutdown_rwsem;
unsigned int shutdown:1;
unsigned int probing:1;
unsigned int in_pm:1;
unsigned int autosuspended:1;
unsigned int txfr_quirk:1; /* Subframe boundaries on transfers */