There is a code sequence where the locking is substream->self_group.lock
-> ins->scbs[index].lock
substream->self_group.lock is interrupt safe, and taken from irq context
as well (trace is snipped for brevity)
so what can happen is
cpu 0 cpu 1
user context user context
take ins->scbs[index].lock without disabling interrupts
get substream->self_group.lock (irqsafe)
try to get ins->scbs[index].lock (spins)
interrupt happens
try to get substream->self_group.lock (spins)
which is an obvious AB-BA deadlock
fix is to just take the lock with _irqsafe
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Jaroslav Kysela <perex@suse.cz>
Acked-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
c6482dde1c