Messages in this thread | | | From | Kevin Hilman <> | Subject | Re: [PATCH] mailbox: cancel timer before starting it | Date | Thu, 24 Sep 2020 09:50:55 -0700 |
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Jerome Brunet <jbrunet@baylibre.com> writes:
> If the txdone is done by polling, it is possible for msg_submit() to start > the timer while txdone_hrtimer() callback is running. If the timer needs > recheduling, it could already be enqueued by the time hrtimer_forward_now() > is called, leading hrtimer to loudly complain. > > WARNING: CPU: 3 PID: 74 at kernel/time/hrtimer.c:932 hrtimer_forward+0xc4/0x110 > CPU: 3 PID: 74 Comm: kworker/u8:1 Not tainted 5.9.0-rc2-00236-gd3520067d01c-dirty #5 > Hardware name: Libre Computer AML-S805X-AC (DT) > Workqueue: events_freezable_power_ thermal_zone_device_check > pstate: 20000085 (nzCv daIf -PAN -UAO BTYPE=--) > pc : hrtimer_forward+0xc4/0x110 > lr : txdone_hrtimer+0xf8/0x118 > [...] > > Canceling the timer before starting it ensure that the timer callback is > not running when the timer is started, solving this race condition. > > Fixes: 0cc67945ea59 ("mailbox: switch to hrtimer for tx_complete polling") > Reported-by: Da Xue <da@libre.computer> > Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Kevin
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