Tirdea, Irina schrieb am 20.07.2015 um 19:45: > > >> -----Original Message----- >> From: Hartmut Knaack [mailto:knaack.h@xxxxxx] >> Sent: 17 July, 2015 11:52 >> To: linux-iio@xxxxxxxxxxxxxxx >> Cc: Jonathan Cameron; Lars-Peter Clausen; Peter Meerwald; Tirdea, Irina; Dogaru, Vlad >> Subject: [PATCH 6/8] iio:magnetometer:bmc150_magn: protect runtime_resume with mutex >> >> Protect bmc150_magn_runtime_resume() with a mutex, as done with other >> suspend/resume functions. >> >> Signed-off-by: Hartmut Knaack <knaack.h@xxxxxx> >> --- >> drivers/iio/magnetometer/bmc150_magn.c | 9 +++++++-- >> 1 file changed, 7 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/iio/magnetometer/bmc150_magn.c b/drivers/iio/magnetometer/bmc150_magn.c >> index e1f804b2b244..ac0cdbde813b 100644 >> --- a/drivers/iio/magnetometer/bmc150_magn.c >> +++ b/drivers/iio/magnetometer/bmc150_magn.c >> @@ -1052,9 +1052,14 @@ static int bmc150_magn_runtime_resume(struct device *dev) >> { >> struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev)); >> struct bmc150_magn_data *data = iio_priv(indio_dev); >> + int ret; >> >> - return bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL, >> - true); >> + mutex_lock(&data->mutex); >> + ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL, >> + true); >> + mutex_unlock(&data->mutex); >> + >> + return ret; > > This function does not have mutex_lock/unlock because it is called with data->mutex locked. > I should have added a comment to specify this. > > Whenever we wake up the device, bmc150_magn_set_power_state is called after locking > data->mutex. This in turn calls pm_runtime_get_sync which will immediately call > bmc150_magn_runtime_resume. Trying to lock the mutex here would lead to a deadlock > (e.g. when trying to read a value through sysfs _raw). > > Since this driver uses autosuspend delay, the situation is different for runtime suspend since > that is called after 2 seconds in a separate thread. This is why there is a mutex locked in runtime > suspend but not in runtime resume. > Yes, please add such a comment. As for me, it seems I have to dig a bit deeper into power management magic - maybe another day ;-) Thanks, Hartmut >> } >> #endif >> >> -- >> 2.4.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
