| Message ID | 1651532668-18873-1-git-send-email-quic_khsieh@quicinc.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] drm/msm/dp: fix event thread stuck in wait_event after kthread_stop() | expand |
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.
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.
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) || + 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) || + kthread_should_stop())); } + + if(kthread_should_stop()) + break; + spin_lock_irqsave(&dp_priv->event_lock, flag); todo = &dp_priv->event_list[dp_priv->event_gndx]; if (todo->delay) {
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(-)