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ALSA: fireworks: accessing to user space outside spinlock
Takashi Sakamoto authored
BugLink: http://bugs.launchpad.net/bugs/1624037

commit 6b1ca4bc

 upstream.

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: default avatarVaishali Thakkar <vaishali.thakkar@oracle.com>
Fixes: 555e8a8f

('ALSA: fireworks: Add command/response functionality into hwdep interface')
Signed-off-by: default avatarTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarTim Gardner <tim.gardner@canonical.com>
Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
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