On 1/27/2025 22:30, Guenter Roeck wrote: > On 1/27/25 01:35, liuchao (CR) wrote: > > On 1/26/25 21:10, Guenter Roeck wrote: > >> On 1/26/25 00:38, Liu Chao wrote: > >>> Every time the user echoes 0 > /dev/watchdog0, meaningless critical > >>> log is printed. > >>> > >> > >> It is not meaningless, and it will still be displayed after this > >> change, making the change pointless. > > > > The change is not pointless. For example, the softdog driver does not > > invoke watchdog_stop or print logs in the watchdog_release. > > > > It seems to me that is a problem in the softdog driver. > > The change is actually worse than I initially thought. > The message is _supposed_ to be displayed if watchdog_stop() is not called while > the watchdog is running (i.e., if err == -EBUSY). > Otherwise it would not be displayed for real hardware watchdogs which are not > stopped because they were running and watchdog_stop() is not called because > WDIOF_MAGICCLOSE is set in the driver and the magic release byte was not > written. > > Specifically, the softdog driver has WDIOF_MAGICCLOSE set. It is not supposed > to be unloadable (or unloaded) while the watchdog is running. When echo to /dev/watchdog0, The watchdog_open, watchdog_write, and watchdog_release functions are invoked in sequence. Do you mean the softdog driver should not call watchdog_release? After the user opens /dev/watchdog0, the user feeds the watchdog through ioctl WDIOC_KEEPALIVE and never closes. Is this the correct usage? > > Guenter
