ALSA: fireworks: accessing to user space outside spinlock
authorTakashi Sakamoto <o-takashi@sakamocchi.jp>
Wed, 31 Aug 2016 13:58:42 +0000 (22:58 +0900)
committerTakashi Iwai <tiwai@suse.de>
Wed, 31 Aug 2016 14:17:15 +0000 (16:17 +0200)
commit6b1ca4bcadf9ef077cc5f03c6822ba276ed14902
tree9f30fa84c9ce173059e7250cba2722a3e763b159
parent04b2d9c9c319277ad4fbbb71855c256a9f4d5f98
ALSA: fireworks: accessing to user space outside spinlock

In hwdep interface of fireworks driver, accessing to user space is in a
critical section with disabled local interrupt. Depending on architecture,
accessing to user space can cause page fault exception. Then local
processor stores machine status and handles the synchronous event. A
handler corresponding to the event can call task scheduler to wait for
preparing pages. In a case of usage of single core processor, the state to
disable local interrupt is worse because it don't handle usual interrupts
from hardware.

This commit fixes this bug, performing the accessing outside spinlock. This
commit also gives up counting the number of queued response messages to
simplify ring-buffer management.

Reported-by: Vaishali Thakkar <vaishali.thakkar@oracle.com>
Cc: stable@vger.kernel.org
Fixes: 555e8a8f7f14('ALSA: fireworks: Add command/response functionality into hwdep interface')
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
sound/firewire/fireworks/fireworks.h
sound/firewire/fireworks/fireworks_hwdep.c
sound/firewire/fireworks/fireworks_proc.c
sound/firewire/fireworks/fireworks_transaction.c