From 1fe7841d892925aff10c3b070937e974d7835d2b Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 6 Dec 2016 11:37:15 +0000
Subject: [PATCH] drm: Don't block the kworker waiting for mode_config.mutex in
output_poll()
If we cannot acquire the mode_config.mutex immediately, just back off and
queue a new attempt after the poll interval. This is mostly to stop the
hung task spam when the system is deadlocked, but it will also lessen
the load (in such extreme cases).
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
[danvet:s/lock/mutex/ per Eric's comment.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161206113715.30382-1-chris@chris-wilson.co.uk
---
drivers/gpu/drm/drm_probe_helper.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index 078d9703a4fe3..ac953f037be7e 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -392,7 +392,11 @@ static void output_poll_execute(struct work_struct *work)
if (!drm_kms_helper_poll)
goto out;
- mutex_lock(&dev->mode_config.mutex);
+ if (!mutex_trylock(&dev->mode_config.mutex)) {
+ repoll = true;
+ goto out;
+ }
+
drm_for_each_connector(connector, dev) {
/* Ignore forced connectors. */
--
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