Messages in this thread | | | Date | Tue, 3 May 2022 09:13:02 -0700 | Subject | Re: [PATCH v2] drm/msm/dp: fix event thread stuck in wait_event after kthread_stop() | From | Kuogee Hsieh <> |
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On 5/2/2022 6:13 PM, Stephen Boyd wrote: > Quoting Kuogee Hsieh (2022-05-02 16:04:28) >> Event thread supposed to exit from its while loop after kthread_stop(). >> However there may has possibility that event thread is pending in the >> middle of wait_event due to condition checking never become true. >> To make sure event thread exit its loop after kthread_stop(), this >> patch OR kthread_should_stop() into wait_event's condition checking >> so that event thread will exit its loop after kernal_stop(). >> >> Changes in v2: >> -- correct spelling error at commit title >> >> Reported-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> >> Fixes: 570d3e5d28db ("drm/msm/dp: stop event kernel thread when DP unbind") >> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com> >> --- >> drivers/gpu/drm/msm/dp/dp_display.c | 11 ++++++++--- >> 1 file changed, 8 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c >> index c388323..5200a58 100644 >> --- a/drivers/gpu/drm/msm/dp/dp_display.c >> +++ b/drivers/gpu/drm/msm/dp/dp_display.c >> @@ -1106,12 +1106,17 @@ static int hpd_event_thread(void *data) >> while (!kthread_should_stop()) { >> if (timeout_mode) { >> wait_event_timeout(dp_priv->event_q, >> - (dp_priv->event_pndx == dp_priv->event_gndx), >> - EVENT_TIMEOUT); >> + ((dp_priv->event_pndx == dp_priv->event_gndx) || > Why the parenthesis (before and after)? > >> + kthread_should_stop()), EVENT_TIMEOUT); >> } else { >> wait_event_interruptible(dp_priv->event_q, >> - (dp_priv->event_pndx != dp_priv->event_gndx)); >> + ((dp_priv->event_pndx != dp_priv->event_gndx) || > Why the parenthesis (before and after)? > >> + kthread_should_stop())); >> } >> + >> + if(kthread_should_stop()) > Missing space after if > >> + break; > Is it possible to move the wait_event to the end of the loop and always > run the loop initially? That way we don't have to check for > kthread_should_stop() again.
no, since we have to make sure q is not empty so that we can proceed to service events.
bu ti thin we can use while (1) instead of while (!kthread_should_stop()) since we have add kthread_should_stop() into wait_event condition checking.
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