WSL2-Linux-Kernel/sound
Arjan van de Ven 763437a9e7 ALSA: pcm - fix race condition in wait_for_avail()
wait_for_avail() in pcm_lib.c has a race in it (observed in practice by an
Intel validation group).

The function is supposed to return once space in the buffer has become
available, or if some timeout happens.  The entity that creates space (irq
handler of sound driver and some such) will do a wake up on a waitqueue
that this function registers for.

However there are two races in the existing code

1) If space became available between the caller noticing there was no
   space and this function actually sleeping, the wakeup is missed and the
   timeout condition will happen instead

2) If a wakeup happened but not sufficient space became available, the
   code will loop again and wait for more space.  However, if the second
   wake comes in prior to hitting the schedule_timeout_interruptible(), it
   will be missed, and potentially you'll wait out until the timeout
   happens.

The fix consists of using more careful setting of the current state (so
that if a wakeup happens in the main loop window, the schedule_timeout()
falls through) and by checking for available space prior to going into the
schedule_timeout() loop, but after being on the waitqueue and having the
state set to interruptible.

[tiwai: the following changes have been added to Arjan's original patch:
 - merged akpm's fix for waitqueue adding order into a single patch
 - reduction of duplicated code of avail check
]

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2011-09-15 09:03:16 +02:00
..
aoa ALSA: sound/aoa/fabrics/layout.c: remove unneeded kfree 2011-08-20 09:27:04 +02:00
arm Merge branch 'for-2.6.39' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound-2.6 into for-2.6.39 2011-04-03 19:28:29 +09:00
atmel Merge branch 'master' into for-next 2011-07-11 14:15:55 +02:00
core ALSA: pcm - fix race condition in wait_for_avail() 2011-09-15 09:03:16 +02:00
drivers i8253: Make pcsp sound driver use the shared i8253_lock 2011-06-09 15:01:39 +02:00
firewire Merge branch 'fix/hda' into topic/misc 2011-06-17 14:54:47 +02:00
i2c [media] tea575x: remove useless input ioctls 2011-07-27 17:53:08 -03:00
isa snd_msnd ->mode is fmode_t, not mode_t 2011-07-26 12:59:29 -04:00
mips sound: Add missing spin_unlock 2010-05-27 09:47:02 +02:00
oss sound: pss - don't use the deprecated function check_region 2011-08-08 14:29:36 +02:00
parisc
pci ALSA: HDA: Cirrus - fix "Surround Speaker" volume control name 2011-09-14 13:45:12 +02:00
pcmcia ALSA: pcmcia - Use pcmcia_request_irq() 2011-07-08 10:11:35 +02:00
ppc treewide: Convert uses of struct resource to resource_size(ptr) 2011-06-10 14:55:36 +02:00
sh sound: sh: ctrl_in/outX to __raw_read/writeX conversion. 2010-10-27 15:53:50 +09:00
soc ASoC: Fix trivial build regression in Kirkwood I2S 2011-09-12 11:48:12 +01:00
sparc atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
spi ALSA: atmel - update author email for ABDAC, AC97C and AT73C213 2011-06-28 16:56:07 +02:00
synth ALSA: emux: Add trivial compat ioctl handler 2010-09-14 16:18:11 +02:00
usb ALSA: usb-audio - Fix missing mixer dB information 2011-08-19 07:55:10 +02:00
Kconfig ALSA: add LaCie FireWire Speakers/Griffin FireWave Surround driver 2011-03-15 08:42:22 +01:00
Makefile ALSA: add LaCie FireWire Speakers/Griffin FireWave Surround driver 2011-03-15 08:42:22 +01:00
ac97_bus.c sound: Fixed line limit issue in sound/ac97_bus.c 2010-12-06 16:09:49 +01:00
last.c
sound_core.c sound: Use sound_register_*() for additional OSS minor devices 2011-03-09 20:10:37 +01:00
sound_firmware.c sound: read i_size with i_size_read() 2011-03-18 15:14:57 +01:00