Messages in this thread | | | Date | Fri, 16 Oct 2020 18:50:39 +0100 | From | Sudeep Holla <> | Subject | Re: [PATCH] mailbox: avoid timer start from callback |
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On Fri, Oct 16, 2020 at 12:30:20PM -0500, jassisinghbrar@gmail.com wrote: > From: Jassi Brar <jaswinder.singh@linaro.org> > > 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 > [...] > > This can be fixed by not starting the timer from the callback path. Which > requires the timer reloading as long as any message is queued on the > channel, and not just when current tx is not done yet. >
I came to similar conclusion and was testing something similar. You bet me. Since we have single timer and multiple channels, each time a message is enqueued on any channel, timer gets added which is wrong.
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
I tested this patch too by reverting offending commit in -next, so
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
You seem to have dropped the Fixes tags. Is that intentional ? If so, any particular reasons. I think it is stable material and better to have fixes tag so that it gets added to stable trees.
-- Regards, Sudeep
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