| Message ID | 20190522162528.5892-1-srinivas.kandagatla@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | soundwire: stream: fix bad unlock balance | expand |
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. > } > > return ret; >
On 22/05/2019 17:25, 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); Looks like I messed this up! I will resend this one! --srini > }
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? --srini >> } >> return ret; >>
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; > > >
On 23/05/2019 10:20, Sanyog Kale wrote: > 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. probably we should just add the lock around the sdw_transfer_defer call in sdw_bank_switch()? This should cleanup the code a bit too. something like: ------------------------------------>cut<----------------------------- diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c index d01060dbee96..f455af5b8151 100644 --- a/drivers/soundwire/stream.c +++ b/drivers/soundwire/stream.c @@ -676,10 +676,13 @@ static int sdw_bank_switch(struct sdw_bus *bus, int m_rt_count) */ multi_link = bus->multi_link && (m_rt_count > 1); - if (multi_link) + if (multi_link) { + mutex_lock(&bus->msg_lock); ret = sdw_transfer_defer(bus, wr_msg, &bus->defer_msg); - else + mutex_unlock(&bus->msg_lock); + } else { ret = sdw_transfer(bus, wr_msg); + } if (ret < 0) { dev_err(bus->dev, "Slave frame_ctrl reg write failed\n"); @@ -742,25 +745,19 @@ static int do_bank_switch(struct sdw_stream_runtime *stream) struct sdw_master_runtime *m_rt = NULL; const struct sdw_master_ops *ops; struct sdw_bus *bus = NULL; - bool multi_link = false; int ret = 0; list_for_each_entry(m_rt, &stream->master_list, stream_node) { bus = m_rt->bus; ops = bus->ops; - if (bus->multi_link) { - multi_link = true; - mutex_lock(&bus->msg_lock); - } - /* Pre-bank switch */ if (ops->pre_bank_switch) { ret = ops->pre_bank_switch(bus); if (ret < 0) { dev_err(bus->dev, "Pre bank switch op failed: %d\n", ret); - goto msg_unlock; + return ret; } } @@ -814,7 +811,6 @@ static int do_bank_switch(struct sdw_stream_runtime *stream) goto error; } - mutex_unlock(&bus->msg_lock); } return ret; @@ -827,16 +823,6 @@ static int do_bank_switch(struct sdw_stream_runtime *stream) kfree(bus->defer_msg.msg); } -msg_unlock: - - if (multi_link) { - list_for_each_entry(m_rt, &stream->master_list, stream_node) { - bus = m_rt->bus; - if (mutex_is_locked(&bus->msg_lock)) - mutex_unlock(&bus->msg_lock); - } - } - return ret; } ------------------------------------>cut<----------------------------- > >> --srini >> >>>> ?????????? } >>>> ?????????? return ret; >>>> >
On Thu, May 23, 2019 at 10:30:20AM +0100, Srinivas Kandagatla wrote: > > > On 23/05/2019 10:20, Sanyog Kale wrote: > > 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. > > probably we should just add the lock around the sdw_transfer_defer call in > sdw_bank_switch()? > This should cleanup the code a bit too. > > something like: > > ------------------------------------>cut<----------------------------- > diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c > index d01060dbee96..f455af5b8151 100644 > --- a/drivers/soundwire/stream.c > +++ b/drivers/soundwire/stream.c > @@ -676,10 +676,13 @@ static int sdw_bank_switch(struct sdw_bus *bus, int > m_rt_count) > */ > multi_link = bus->multi_link && (m_rt_count > 1); > > - if (multi_link) > + if (multi_link) { > + mutex_lock(&bus->msg_lock); > ret = sdw_transfer_defer(bus, wr_msg, &bus->defer_msg); > - else > + mutex_unlock(&bus->msg_lock); you cant release bus_lock here since message is not yet transferred. we can only release bus_lock after sdw_ml_sync_bank_switch function where we confirm that message transfer is completed. > + } else { > ret = sdw_transfer(bus, wr_msg); > + } > > if (ret < 0) { > dev_err(bus->dev, "Slave frame_ctrl reg write failed\n"); > @@ -742,25 +745,19 @@ static int do_bank_switch(struct sdw_stream_runtime > *stream) > struct sdw_master_runtime *m_rt = NULL; > const struct sdw_master_ops *ops; > struct sdw_bus *bus = NULL; > - bool multi_link = false; > int ret = 0; > > list_for_each_entry(m_rt, &stream->master_list, stream_node) { > bus = m_rt->bus; > ops = bus->ops; > > - if (bus->multi_link) { > - multi_link = true; > - mutex_lock(&bus->msg_lock); > - } > - > /* Pre-bank switch */ > if (ops->pre_bank_switch) { > ret = ops->pre_bank_switch(bus); > if (ret < 0) { > dev_err(bus->dev, > "Pre bank switch op failed: %d\n", > ret); > - goto msg_unlock; > + return ret; > } > } > > @@ -814,7 +811,6 @@ static int do_bank_switch(struct sdw_stream_runtime > *stream) > goto error; > } > > - mutex_unlock(&bus->msg_lock); > } > > return ret; > @@ -827,16 +823,6 @@ static int do_bank_switch(struct sdw_stream_runtime > *stream) > kfree(bus->defer_msg.msg); > } > > -msg_unlock: > - > - if (multi_link) { > - list_for_each_entry(m_rt, &stream->master_list, stream_node) > { > - bus = m_rt->bus; > - if (mutex_is_locked(&bus->msg_lock)) > - mutex_unlock(&bus->msg_lock); > - } > - } > - > return ret; > } > > ------------------------------------>cut<----------------------------- > > > > > --srini > > > > > > > > ?????????? } > > > > > ?????????? return ret; > > > > > > >
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); } return ret;
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(-)