On Monday 22 November 2021 19:50:14 Armin Wolf wrote: > Am 22.11.21 um 18:55 schrieb Guenter Roeck: > > On 11/22/21 8:01 AM, Pali Rohár wrote: > > > On Saturday 20 November 2021 18:03:19 Armin Wolf wrote: > > > > The only purpose of i8k_ioctl() is to call i8k_ioctl_unlocked() > > > > with i8k_mutex held. Judging from the hwmon code, this mutex > > > > only needs to be held when setting the fan speed/mode. > > > > > > Really? I think that there is no difference between setting and getting > > > fan speed/mode. At least I do not see why 'set' needs mutex and 'get' do > > > not need it. Some more explanation is needed... > > > > > I8K_SET_FAN sets the fan speed and returns the current status. Without > > locking, the returned status may not match or be associated with the > > previous > > set operation. > > > > Maybe that doesn't matter, and the synchronization is not needed. If so, > > you can probably remove the locking entirely. > > > > Guenter > > That is the reason i kept the locking code. Since i do not want to break > the ioctl interfacein any way, removing the locking code seems too risky > to me. I see. That is a good point. But there is same race condition also when at the same time going to change speed via ioctl and also via hwmon sysfs.
