On Tue, 22 Nov 2022, Thomas Gleixner wrote: > Tearing down timers which have circular dependencies to other > functionality, e.g. workqueues, where the timer can schedule work and work > can arm timers is not trivial. > > In those cases it is desired to shutdown the timer in a way which prevents > rearming of the timer. The mechanism to do so it to set timer->function to > NULL and use this as an indicator for the timer arming functions to ignore > the (re)arm request. > > In preparation for that replace the warnings in the relevant code pathes > with checks for timer->function == NULL and discard the rearm request > silently. > > Add debug_assert_init() instead of the WARN_ON_ONCE(!timer->function) > checks so that debug objects can warn about non-initialized timers. Could you expand this paragraph, so that is is not missleading when a reader is not aware of the details of debug objects? Otherwise it seems to the reader that debug objects will warn when timer->function == NULL. The warning of debug objects does not cover the original WARN_ON_ONCE(!timer->function). It warns when timer was not initialized using timer_setup[_on_stack]() or via DEFINE_TIMER(). > If developers fail to enable debug objects and then waste lots of time to > figure out why their non-initialized timer is not firing, they deserve it. Thanks, Anna-Maria
