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authorTakashi Iwai <tiwai@suse.de>2014-05-02 18:17:06 +0200
committerTakashi Iwai <tiwai@suse.de>2014-05-02 18:17:06 +0200
commit1ee23fe07ee83a38ecee927e701f762888ada942 (patch)
treef8af5087956bef2a461410b49584dc3bd2cd988c /sound/usb
parent1c53e7253ed8769a00afa0f06777d731dbe1ba6f (diff)
ALSA: usb-audio: Fix deadlocks at resuming
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>
Diffstat (limited to 'sound/usb')
-rw-r--r--sound/usb/card.c7
-rw-r--r--sound/usb/usbaudio.h1
2 files changed, 6 insertions, 2 deletions
diff --git a/sound/usb/card.c b/sound/usb/card.c
index e769d3977716..c3b5b7dca1c3 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -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;
}
diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index 25c4c7e217de..91d0380431b4 100644
--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -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 */