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* [PATCH 1/2] drm/atomic: fix self-refresh helpers crtc state dereference
@ 2019-11-01 18:07 Rob Clark
  2019-11-01 18:07 ` [PATCH 2/2] drm/atomic: clear new_state pointers at hw_done Rob Clark
  2019-11-01 20:06 ` [PATCH 1/2] drm/atomic: fix self-refresh helpers crtc state dereference Sean Paul
  0 siblings, 2 replies; 15+ messages in thread
From: Rob Clark @ 2019-11-01 18:07 UTC (permalink / raw)
  To: dri-devel
  Cc: Sean Paul, Maarten Lankhorst, Rob Clark, Maxime Ripard, Sean Paul,
	David Airlie, Daniel Vetter, open list

From: Rob Clark <robdclark@chromium.org>

drm_self_refresh_helper_update_avg_times() was incorrectly accessing the
new incoming state after drm_atomic_helper_commit_hw_done().  But this
state might have already been superceeded by an !nonblock atomic update
resulting in dereferencing an already free'd crtc_state.

Fixes: d4da4e33341c ("drm: Measure Self Refresh Entry/Exit times to avoid thrashing")
Cc: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>
---
TODO I *think* this will more or less do the right thing.. althought I'm
not 100% sure if, for example, we enter psr in a nonblock commit, and
then leave psr in a !nonblock commit that overtakes the completion of
the nonblock commit.  Not sure if this sort of scenario can happen in
practice.  But not crashing is better than crashing, so I guess we
should either take this patch or rever the self-refresh helpers until
Sean can figure out a better solution.

 drivers/gpu/drm/drm_atomic_helper.c       |  2 ++
 drivers/gpu/drm/drm_self_refresh_helper.c | 11 ++++++-----
 include/drm/drm_atomic.h                  |  8 ++++++++
 3 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 3ef2ac52ce94..732bd0ce9241 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -2240,6 +2240,8 @@ void drm_atomic_helper_commit_hw_done(struct drm_atomic_state *old_state)
 	int i;
 
 	for_each_oldnew_crtc_in_state(old_state, crtc, old_crtc_state, new_crtc_state, i) {
+		old_state->crtcs[i].new_self_refresh_active = new_crtc_state->self_refresh_active;
+
 		commit = new_crtc_state->commit;
 		if (!commit)
 			continue;
diff --git a/drivers/gpu/drm/drm_self_refresh_helper.c b/drivers/gpu/drm/drm_self_refresh_helper.c
index 68f4765a5896..77b9079fa578 100644
--- a/drivers/gpu/drm/drm_self_refresh_helper.c
+++ b/drivers/gpu/drm/drm_self_refresh_helper.c
@@ -143,19 +143,20 @@ void drm_self_refresh_helper_update_avg_times(struct drm_atomic_state *state,
 					      unsigned int commit_time_ms)
 {
 	struct drm_crtc *crtc;
-	struct drm_crtc_state *old_crtc_state, *new_crtc_state;
+	struct drm_crtc_state *old_crtc_state;
 	int i;
 
-	for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state,
-				      new_crtc_state, i) {
+	for_each_old_crtc_in_state(state, crtc, old_crtc_state, i) {
+		bool new_self_refresh_active =
+				state->crtcs[i].new_self_refresh_active;
 		struct drm_self_refresh_data *sr_data = crtc->self_refresh_data;
 		struct ewma_psr_time *time;
 
 		if (old_crtc_state->self_refresh_active ==
-		    new_crtc_state->self_refresh_active)
+		    new_self_refresh_active)
 			continue;
 
-		if (new_crtc_state->self_refresh_active)
+		if (new_self_refresh_active)
 			time = &sr_data->entry_avg_ms;
 		else
 			time = &sr_data->exit_avg_ms;
diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index 927e1205d7aa..86baf2b38bb3 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -155,6 +155,14 @@ struct __drm_crtcs_state {
 	struct drm_crtc *ptr;
 	struct drm_crtc_state *state, *old_state, *new_state;
 
+	/**
+	 * @new_self_refresh_active:
+	 *
+	 * drm_atomic_helper_commit_hw_done() stashes new_crtc_state->self_refresh_active
+	 * so that it can be accessed late in drm_self_refresh_helper_update_avg_times().
+	 */
+	bool new_self_refresh_active;
+
 	/**
 	 * @commit:
 	 *
-- 
2.21.0


^ permalink raw reply related	[flat|nested] 15+ messages in thread

end of thread, other threads:[~2019-11-06  2:58 UTC | newest]

Thread overview: 15+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2019-11-01 18:07 [PATCH 1/2] drm/atomic: fix self-refresh helpers crtc state dereference Rob Clark
2019-11-01 18:07 ` [PATCH 2/2] drm/atomic: clear new_state pointers at hw_done Rob Clark
2019-11-01 18:33   ` Maarten Lankhorst
2019-11-01 19:44     ` Rob Clark
2019-11-01 19:24   ` Ville Syrjälä
2019-11-01 19:49     ` Rob Clark
2019-11-01 21:44       ` Ville Syrjälä
2019-11-01 22:14         ` Rob Clark
2019-11-04 18:41           ` Ville Syrjälä
2019-11-04 19:13             ` Rob Clark
2019-11-04 20:50               ` Ville Syrjälä
2019-11-04 21:11                 ` Rob Clark
2019-11-06  2:58   ` [drm/atomic] 554231a5c5: BUG:kernel_NULL_pointer_dereference,address kernel test robot
2019-11-01 20:06 ` [PATCH 1/2] drm/atomic: fix self-refresh helpers crtc state dereference Sean Paul
2019-11-04  9:29   ` Maarten Lankhorst

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