From: Ionela Voinescu <ionela.voinescu@arm.com>
To: Jassi Brar <jassisinghbrar@gmail.com>
Cc: Jerome Brunet <jbrunet@baylibre.com>,
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 09:52:17 +0100 [thread overview]
Message-ID: <20201016085217.GA12323@arm.com> (raw)
In-Reply-To: <CABb+yY1-MBac0e6xQwWkHRo3bqJNMWb4xQzdaGdrYT=n5zRvtw@mail.gmail.com>
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.
Thanks,
Ionela.
> thanks
next prev parent reply other threads:[~2020-10-16 8:52 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-23 12:39 [PATCH] mailbox: cancel timer before starting it Jerome Brunet
2020-09-24 16:50 ` Kevin Hilman
2020-10-15 13:46 ` Ionela Voinescu
2020-10-15 13:58 ` Jerome Brunet
2020-10-15 14:29 ` Ionela Voinescu
2020-10-16 8:44 ` Sudeep Holla
2020-10-16 9:02 ` Jerome Brunet
2020-10-16 9:34 ` Sudeep Holla
2020-10-16 11:47 ` Sudeep Holla
2020-10-15 18:45 ` Jassi Brar
2020-10-16 8:52 ` Ionela Voinescu [this message]
2020-10-16 9:00 ` Jerome Brunet
2020-10-16 13:52 ` Sudeep Holla
2020-10-16 17:33 ` Jassi Brar
2020-10-16 18:54 ` Jerome Brunet
2020-10-16 19:27 ` Jassi Brar
2022-07-19 7:08 ` Da Xue
2020-10-16 11:52 ` Sudeep Holla
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