On 27/06/22 11:50, Juri Lelli wrote: > Changes to hrtimer mode (potentially made by __hrtimer_init_sleeper on > PREEMPT_RT) are not visible to hrtimer_start_range_ns, thus not > accounted for by hrtimer_start_expires call paths. In particular, > __wait_event_hrtimeout suffers from this problem as we have, for > example: > > fs/aio.c::read_events > wait_event_interruptible_hrtimeout > __wait_event_hrtimeout > hrtimer_init_sleeper_on_stack <- this might "mode |= HRTIMER_MODE_HARD" > on RT if task runs at RT/DL priority > hrtimer_start_range_ns > WARN_ON_ONCE(!(mode & HRTIMER_MODE_HARD) ^ !timer->is_hard) > fires since the latter doesn't see the change of mode done by > init_sleeper > > Fix it by making __wait_event_hrtimeout call hrtimer_sleeper_start_expires, > which is aware of the special RT/DL case, instead of hrtimer_start_range_ns. > > Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> > Reported-by: Bruno Goncalves <bgoncalv@xxxxxxxxxx> > Signed-off-by: Juri Lelli <juri.lelli@xxxxxxxxxx> Makes sense, that's now aligned with what e.g. schedule_hrtimer_range_clock() does. Reviewed-by: Valentin Schneider <vschneid@xxxxxxxxxx>
