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 <[email protected]>
Fixes: 570d3e5d28db ("drm/msm/dp: stop event kernel thread when DP unbind")
Signed-off-by: Kuogee Hsieh <[email protected]>
---
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) ||
+ 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) {
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
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 <[email protected]>
> Fixes: 570d3e5d28db ("drm/msm/dp: stop event kernel thread when DP unbind")
> Signed-off-by: Kuogee Hsieh <[email protected]>
> ---
> 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 <[email protected]>
>> Fixes: 570d3e5d28db ("drm/msm/dp: stop event kernel thread when DP unbind")
>> Signed-off-by: Kuogee Hsieh <[email protected]>
>> ---
>> 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.