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 <[email protected]>
---
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);
}
return ret;
--
2.21.0
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 <[email protected]>
> ---
> 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<[email protected]>
> ---
> 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 <[email protected]>
>> ---
>> 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 <[email protected]>
> > > ---
> > > ?? 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 <[email protected]>
>>>> ---
>>>> ?? 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 <[email protected]>
> > > > > ---
> > > > > ?? 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;
> > > > >
> >
--