On Thu, May 23, 2019 at 09:43:14AM +0100, Srinivas Kandagatla wrote:
On 22/05/2019 17:41, Pierre-Louis Bossart wrote:
On 5/22/19 11:25 AM, Srinivas Kandagatla wrote:
This patch fixes below warning due to unlocking without locking.
?? ===================================== ?? WARNING: bad unlock balance detected! ?? 5.1.0-16506-gc1c383a6f0a2-dirty #1523 Tainted: G?????????????? W ?? ------------------------------------- ?? aplay/2954 is trying to release lock (&bus->msg_lock) at: ?? do_bank_switch+0x21c/0x480 ?? but there are no more locks to release!
Signed-off-by: Srinivas Kandagatla srinivas.kandagatla@linaro.org
?? drivers/soundwire/stream.c | 3 ++- ?? 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c index 544925ff0b40..d16268f30e4f 100644 --- a/drivers/soundwire/stream.c +++ b/drivers/soundwire/stream.c @@ -814,7 +814,8 @@ static int do_bank_switch(struct sdw_stream_runtime *stream) ?????????????????????????? goto error; ?????????????????? } -?????????????? mutex_unlock(&bus->msg_lock); +?????????????? if (mutex_is_locked(&bus->msg_lock)) +?????????????????????? utex_unlock(&bus->msg_lock);
Does this even compile? should be mutex_unlock, no?
We also may want to identify the issue in more details without pushing it under the rug. The locking mechanism is far from simple and it's likely there are a number of problems with it.
msg_lock is taken conditionally during multi link bank switch cases, however the unlock is done unconditionally leading to this warning.
Having a closer look show that there could be a dead lock in this path while executing sdw_transfer(). And infact there is no need to take msg_lock in multi link switch cases as sdw_transfer should take care of this.
Vinod/Sanyog any reason why msg_lock is really required in this path?
In case of multi link we use sdw_transfer_defer instead of sdw_transfer where lock is not acquired, hence lock is acquired in do_bank_switch for multi link. we should add same check of multi link to release lock in do_bank_switch.
--srini
?????????? } ?????????? return ret;
--