From 2f9b5b3ae2eb625b75a898212a76f3b8c6d0d2b0 Mon Sep 17 00:00:00 2001
From: Kuogee Hsieh <quic_khsieh@quicinc.com>
Date: Tue, 3 May 2022 09:25:36 -0700
Subject: [PATCH] drm/msm/dp: fix event thread stuck in wait_event after kthread_stop()
Git-commit: 2f9b5b3ae2eb625b75a898212a76f3b8c6d0d2b0
Patch-mainline: v5.19-rc1
References: git-fixes

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

Changes in v3:
-- remove unnecessary parenthesis
-- while(1) to replace while (!kthread_should_stop())

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>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/484576/
Link: https://lore.kernel.org/r/1651595136-24312-1-git-send-email-quic_khsieh@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/msm/dp/dp_display.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index c38832304353..da5c03a8cc4c 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -1103,15 +1103,20 @@ static int hpd_event_thread(void *data)
 
 	dp_priv = (struct dp_display_private *)data;
 
-	while (!kthread_should_stop()) {
+	while (1) {
 		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) {
-- 
2.35.3