commit d80771c083 upstream.
When compiling with CONFIG_DEBUG_ATOMIC_SLEEP=y the mxs-dcp driver
prints warnings such as:
WARNING: CPU: 0 PID: 120 at kernel/sched/core.c:7736 __might_sleep+0x98/0x9c
do not call blocking ops when !TASK_RUNNING; state=1 set at [<8081978c>] dcp_chan_thread_sha+0x3c/0x2ec
The problem is that blocking ops will manipulate current->state
themselves so it is not allowed to call them between
set_current_state(TASK_INTERRUPTIBLE) and schedule().
Fix this by converting the per-chan mutex to a spinlock (it only
protects tiny list ops anyway) and rearranging the wait logic so that
callbacks are called current->state as TASK_RUNNING. Those callbacks
will indeed call blocking ops themselves so this is required.
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
d585747f95