| Message ID | 20230227112933.1593997-1-rf@opensource.cirrus.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | soundwire: bus: Fix unbalanced pm_runtime_put() causing usage count underflow | expand |
On 2/27/23 06:29, Richard Fitzgerald wrote: > This reverts commit > 443a98e649b4 ("soundwire: bus: use pm_runtime_resume_and_get()") > > Change calls to pm_runtime_resume_and_get() back to pm_runtime_get_sync(). > This fixes a usage count underrun caused by doing a pm_runtime_put() even > though pm_runtime_resume_and_get() returned an error. > > The three affected functions ignore -EACCES error from trying to get > pm_runtime, and carry on, including a put at the end of the function. > But pm_runtime_resume_and_get() does not increment the usage count if it > returns an error. So in the -EACCES case you must not call > pm_runtime_put(). > > The documentation for pm_runtime_get_sync() says: > "Consider using pm_runtime_resume_and_get() ... as this is likely to > result in cleaner code." > > In this case I don't think it results in cleaner code because the > pm_runtime_put() at the end of the function would have to be conditional on > the return value from pm_runtime_resume_and_get() at the top of the > function. > > pm_runtime_get_sync() doesn't have this problem because it always > increments the count, so always needs a put. The code can just flow through > and do the pm_runtime_put() unconditionally. > > Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com> Agreed, in hindsight the move to use pm_runtime_resume_and_get() mostly added issues left and right with limited benefits - just too hard to review and figure out what cases work and which ones don't. Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> > --- > drivers/soundwire/bus.c | 15 ++++++++++----- > 1 file changed, 10 insertions(+), 5 deletions(-) > > diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c > index 76515c33e639..4fd221d0cc81 100644 > --- a/drivers/soundwire/bus.c > +++ b/drivers/soundwire/bus.c > @@ -571,9 +571,11 @@ int sdw_nread(struct sdw_slave *slave, u32 addr, size_t count, u8 *val) > { > int ret; > > - ret = pm_runtime_resume_and_get(&slave->dev); > - if (ret < 0 && ret != -EACCES) > + ret = pm_runtime_get_sync(&slave->dev); > + if (ret < 0 && ret != -EACCES) { > + pm_runtime_put_noidle(&slave->dev); > return ret; > + } > > ret = sdw_nread_no_pm(slave, addr, count, val); > > @@ -595,9 +597,11 @@ int sdw_nwrite(struct sdw_slave *slave, u32 addr, size_t count, const u8 *val) > { > int ret; > > - ret = pm_runtime_resume_and_get(&slave->dev); > - if (ret < 0 && ret != -EACCES) > + ret = pm_runtime_get_sync(&slave->dev); > + if (ret < 0 && ret != -EACCES) { > + pm_runtime_put_noidle(&slave->dev); > return ret; > + } > > ret = sdw_nwrite_no_pm(slave, addr, count, val); > > @@ -1565,9 +1569,10 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave) > > sdw_modify_slave_status(slave, SDW_SLAVE_ALERT); > > - ret = pm_runtime_resume_and_get(&slave->dev); > + ret = pm_runtime_get_sync(&slave->dev); > if (ret < 0 && ret != -EACCES) { > dev_err(&slave->dev, "Failed to resume device: %d\n", ret); > + pm_runtime_put_noidle(&slave->dev); > return ret; > } >
diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c index 76515c33e639..4fd221d0cc81 100644 --- a/drivers/soundwire/bus.c +++ b/drivers/soundwire/bus.c @@ -571,9 +571,11 @@ int sdw_nread(struct sdw_slave *slave, u32 addr, size_t count, u8 *val) { int ret; - ret = pm_runtime_resume_and_get(&slave->dev); - if (ret < 0 && ret != -EACCES) + ret = pm_runtime_get_sync(&slave->dev); + if (ret < 0 && ret != -EACCES) { + pm_runtime_put_noidle(&slave->dev); return ret; + } ret = sdw_nread_no_pm(slave, addr, count, val); @@ -595,9 +597,11 @@ int sdw_nwrite(struct sdw_slave *slave, u32 addr, size_t count, const u8 *val) { int ret; - ret = pm_runtime_resume_and_get(&slave->dev); - if (ret < 0 && ret != -EACCES) + ret = pm_runtime_get_sync(&slave->dev); + if (ret < 0 && ret != -EACCES) { + pm_runtime_put_noidle(&slave->dev); return ret; + } ret = sdw_nwrite_no_pm(slave, addr, count, val); @@ -1565,9 +1569,10 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave) sdw_modify_slave_status(slave, SDW_SLAVE_ALERT); - ret = pm_runtime_resume_and_get(&slave->dev); + ret = pm_runtime_get_sync(&slave->dev); if (ret < 0 && ret != -EACCES) { dev_err(&slave->dev, "Failed to resume device: %d\n", ret); + pm_runtime_put_noidle(&slave->dev); return ret; }
This reverts commit 443a98e649b4 ("soundwire: bus: use pm_runtime_resume_and_get()") Change calls to pm_runtime_resume_and_get() back to pm_runtime_get_sync(). This fixes a usage count underrun caused by doing a pm_runtime_put() even though pm_runtime_resume_and_get() returned an error. The three affected functions ignore -EACCES error from trying to get pm_runtime, and carry on, including a put at the end of the function. But pm_runtime_resume_and_get() does not increment the usage count if it returns an error. So in the -EACCES case you must not call pm_runtime_put(). The documentation for pm_runtime_get_sync() says: "Consider using pm_runtime_resume_and_get() ... as this is likely to result in cleaner code." In this case I don't think it results in cleaner code because the pm_runtime_put() at the end of the function would have to be conditional on the return value from pm_runtime_resume_and_get() at the top of the function. pm_runtime_get_sync() doesn't have this problem because it always increments the count, so always needs a put. The code can just flow through and do the pm_runtime_put() unconditionally. Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com> --- drivers/soundwire/bus.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)