On Fri 16 Oct 2020 at 10:52, Ionela Voinescu <ionela.voine...@arm.com> wrote:
> On Thursday 15 Oct 2020 at 13:45:54 (-0500), Jassi Brar wrote: > [..] >> > >> --- a/drivers/mailbox/mailbox.c >> > >> +++ b/drivers/mailbox/mailbox.c >> > >> @@ -82,9 +82,13 @@ static void msg_submit(struct mbox_chan *chan) >> > >> exit: >> > >> spin_unlock_irqrestore(&chan->lock, flags); >> > >> >> > >> - if (!err && (chan->txdone_method & TXDONE_BY_POLL)) >> > >> - /* kick start the timer immediately to avoid delays */ >> > >> + if (!err && (chan->txdone_method & TXDONE_BY_POLL)) { >> > >> + /* Disable the timer if already active ... */ >> > >> + hrtimer_cancel(&chan->mbox->poll_hrt); >> > >> + >> > >> + /* ... and kick start it immediately to avoid delays */ >> > >> hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL); >> > >> + } >> > >> } >> > >> >> > >> static void tx_tick(struct mbox_chan *chan, int r) >> > > >> > > I've tracked a regression back to this commit. Details to reproduce: >> > >> > Hi Ionela, >> > >> > I don't have access to your platform and I don't get what is going on >> > from the log below. >> > >> > Could you please give us a bit more details about what is going on ? >> > >> > All this patch does is add hrtimer_cancel(). >> > * It is needed if the timer had already been started, which is >> > appropriate AFAIU >> > * It is a NO-OP is the timer is not active. >> > >> Can you please try using hrtimer_try_to_cancel() instead ? >> > > Yes, using hrtimer_try_to_cancel() instead works for me. But doesn't > this limit how effective this change is? AFAIU, this will possibly only > reduce the chances for the race condition, but not solve it. > It is also my understanding, hrtimer_try_to_cancel() would remove a timer which as not already started but would return withtout doing anything if the callback is already running ... which is the original problem > Thanks, > Ionela. > >> thanks