From: Jerome Brunet <jbrunet@baylibre.com> To: Ionela Voinescu <ionela.voinescu@arm.com>, Jassi Brar <jassisinghbrar@gmail.com> Cc: Kevin Hilman <khilman@baylibre.com>, "open list\:ARM\/Amlogic Meson..." <linux-amlogic@lists.infradead.org>, Da Xue <da@libre.computer>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org> Subject: Re: [PATCH] mailbox: cancel timer before starting it Date: Fri, 16 Oct 2020 11:00:37 +0200 [thread overview] Message-ID: <1jk0vqk0ju.fsf@starbuckisacylon.baylibre.com> (raw) In-Reply-To: <20201016085217.GA12323@arm.com> On Fri 16 Oct 2020 at 10:52, Ionela Voinescu <ionela.voinescu@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
WARNING: multiple messages have this Message-ID (diff)
From: Jerome Brunet <jbrunet@baylibre.com> To: Ionela Voinescu <ionela.voinescu@arm.com>, Jassi Brar <jassisinghbrar@gmail.com> Cc: Kevin Hilman <khilman@baylibre.com>, Da Xue <da@libre.computer>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, "open list:ARM/Amlogic Meson..." <linux-amlogic@lists.infradead.org> Subject: Re: [PATCH] mailbox: cancel timer before starting it Date: Fri, 16 Oct 2020 11:00:37 +0200 [thread overview] Message-ID: <1jk0vqk0ju.fsf@starbuckisacylon.baylibre.com> (raw) In-Reply-To: <20201016085217.GA12323@arm.com> On Fri 16 Oct 2020 at 10:52, Ionela Voinescu <ionela.voinescu@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 _______________________________________________ linux-amlogic mailing list linux-amlogic@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-amlogic
next prev parent reply other threads:[~2020-10-16 9:00 UTC|newest] Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-09-23 12:39 [PATCH] mailbox: cancel timer before starting it Jerome Brunet 2020-09-23 12:39 ` Jerome Brunet 2020-09-24 16:50 ` Kevin Hilman 2020-09-24 16:50 ` Kevin Hilman 2020-10-15 13:46 ` Ionela Voinescu 2020-10-15 13:46 ` Ionela Voinescu 2020-10-15 13:58 ` Jerome Brunet 2020-10-15 13:58 ` Jerome Brunet 2020-10-15 14:29 ` Ionela Voinescu 2020-10-15 14:29 ` Ionela Voinescu 2020-10-16 8:44 ` Sudeep Holla 2020-10-16 8:44 ` Sudeep Holla 2020-10-16 9:02 ` Jerome Brunet 2020-10-16 9:02 ` Jerome Brunet 2020-10-16 9:34 ` Sudeep Holla 2020-10-16 9:34 ` Sudeep Holla 2020-10-16 11:47 ` Sudeep Holla 2020-10-16 11:47 ` Sudeep Holla 2020-10-15 18:45 ` Jassi Brar 2020-10-15 18:45 ` Jassi Brar 2020-10-16 8:52 ` Ionela Voinescu 2020-10-16 8:52 ` Ionela Voinescu 2020-10-16 9:00 ` Jerome Brunet [this message] 2020-10-16 9:00 ` Jerome Brunet 2020-10-16 13:52 ` Sudeep Holla 2020-10-16 13:52 ` Sudeep Holla 2020-10-16 17:33 ` Jassi Brar 2020-10-16 17:33 ` Jassi Brar 2020-10-16 18:54 ` Jerome Brunet 2020-10-16 18:54 ` Jerome Brunet 2020-10-16 19:27 ` Jassi Brar 2020-10-16 19:27 ` Jassi Brar 2022-07-19 7:08 ` Da Xue 2022-07-19 7:08 ` Da Xue 2020-10-16 11:52 ` Sudeep Holla 2020-10-16 11:52 ` Sudeep Holla
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