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.