Skip to contentSkip to conversation

Patch "drm/radeon: Fix deadlock on runtime suspend" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Mar 12, 2018

Subsystems (3)
Stable branch DRM drivers Radeon and amdgpu DRM drivers
lore
Share & tools
lore

[email protected]

author maintainer Applied
#0 lore raw

This is a note to let you know that I've just added the patch titled

drm/radeon: Fix deadlock on runtime suspend

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-radeon-fix-deadlock-on-runtime-suspend.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 15734feff2bdac24aa3266c437cffa42851990e3 Mon Sep 17 00:00:00 2001

From: Lukas Wunner <[email protected]>
Date: Sun, 11 Feb 2018 10:38:28 +0100
Subject: drm/radeon: Fix deadlock on runtime suspend

From: Lukas Wunner <[email protected]>

commit 15734feff2bdac24aa3266c437cffa42851990e3 upstream.

radeon's ->runtime_suspend hook calls drm_kms_helper_poll_disable(), which waits for the output poll worker to finish if it's running.

The output poll worker meanwhile calls pm_runtime_get_sync() in radeon's ->detect hooks, which waits for the ongoing suspend to finish, causing a deadlock.

Fix by not acquiring a runtime PM ref if the ->detect hooks are called in the output poll worker's context. This is safe because the poll worker is only enabled while runtime active and we know that ->runtime_suspend waits for it to finish.

Stack trace for posterity:

  INFO: task kworker/0:3:31847 blocked for more than 120 seconds
  Workqueue: events output_poll_execute [drm_kms_helper]
  Call Trace:
   schedule+0x3c/0x90
   rpm_resume+0x1e2/0x690
   __pm_runtime_resume+0x3f/0x60
   radeon_lvds_detect+0x39/0xf0 [radeon]
   output_poll_execute+0xda/0x1e0 [drm_kms_helper]
   process_one_work+0x14b/0x440
   worker_thread+0x48/0x4a0

  INFO: task kworker/2:0:10493 blocked for more than 120 seconds.
  Workqueue: pm pm_runtime_work
  Call Trace:
   schedule+0x3c/0x90
   schedule_timeout+0x1b3/0x240
   wait_for_common+0xc2/0x180
   wait_for_completion+0x1d/0x20
   flush_work+0xfc/0x1a0
   __cancel_work_timer+0xa5/0x1d0
   cancel_delayed_work_sync+0x13/0x20
   drm_kms_helper_poll_disable+0x1f/0x30 [drm_kms_helper]
   radeon_pmops_runtime_suspend+0x3d/0xa0 [radeon]
   pci_pm_runtime_suspend+0x61/0x1a0
   vga_switcheroo_runtime_suspend+0x21/0x70
   __rpm_callback+0x32/0x70
   rpm_callback+0x24/0x80
   rpm_suspend+0x12b/0x640
   pm_runtime_work+0x6f/0xb0
   process_one_work+0x14b/0x440
   worker_thread+0x48/0x4a0

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94147

Fixes 10ebc0bc0934 ("drm/radeon: add runtime PM support (v2)")
Cc [email protected] # v3.13+: 27d4ee03078a: workqueue: Allow retrieval of current task's work struct
Cc [email protected] # v3.13+: 25c058ccaf2e: drm: Allow determining if current task is output poll worker
Cc Ismo Toijala <[email protected]>
Cc Alex Deucher <[email protected]>
Cc Dave Airlie <[email protected]>
Reviewed-by Lyude Paul <[email protected]>
Signed-off-by Lukas Wunner <[email protected]>
Link https://patchwork.freedesktop.org/patch/msgid/64ea02c44f91dda19bc563902b97bbc699040392.1518338789.git.lukas@wunner.de
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 drivers/gpu/drm/radeon/radeon_connectors.c |   74 +++++++++++++++++++----------
 1 file changed, 49 insertions(+), 25 deletions(-)
drivers/gpu/drm/radeon/radeon_connectors.c +49 -25
@@ -891,9 +891,11 @@ radeon_lvds_detect(struct drm_connector
 	enum drm_connector_status ret = connector_status_disconnected;
 	int r;
 
-	r = pm_runtime_get_sync(connector->dev->dev);
-	if (r < 0)
-		return connector_status_disconnected;
+	if (!drm_kms_helper_is_poll_worker()) {
+		r = pm_runtime_get_sync(connector->dev->dev);
+		if (r < 0)
+			return connector_status_disconnected;
+	}
 
 	if (encoder) {
 		struct radeon_encoder *radeon_encoder = to_radeon_encoder(encoder);

@@ -916,8 +918,12 @@ radeon_lvds_detect(struct drm_connector
 	/* check acpi lid status ??? */
 
 	radeon_connector_update_scratch_regs(connector, ret);
-	pm_runtime_mark_last_busy(connector->dev->dev);
-	pm_runtime_put_autosuspend(connector->dev->dev);
+
+	if (!drm_kms_helper_is_poll_worker()) {
+		pm_runtime_mark_last_busy(connector->dev->dev);
+		pm_runtime_put_autosuspend(connector->dev->dev);
+	}
+
 	return ret;
 }
 

@@ -1020,9 +1026,11 @@ radeon_vga_detect(struct drm_connector *
 	enum drm_connector_status ret = connector_status_disconnected;
 	int r;
 
-	r = pm_runtime_get_sync(connector->dev->dev);
-	if (r < 0)
-		return connector_status_disconnected;
+	if (!drm_kms_helper_is_poll_worker()) {
+		r = pm_runtime_get_sync(connector->dev->dev);
+		if (r < 0)
+			return connector_status_disconnected;
+	}
 
 	encoder = radeon_best_single_encoder(connector);
 	if (!encoder)

@@ -1089,8 +1097,10 @@ radeon_vga_detect(struct drm_connector *
 	radeon_connector_update_scratch_regs(connector, ret);
 
 out:
-	pm_runtime_mark_last_busy(connector->dev->dev);
-	pm_runtime_put_autosuspend(connector->dev->dev);
+	if (!drm_kms_helper_is_poll_worker()) {
+		pm_runtime_mark_last_busy(connector->dev->dev);
+		pm_runtime_put_autosuspend(connector->dev->dev);
+	}
 
 	return ret;
 }

@@ -1153,9 +1163,11 @@ radeon_tv_detect(struct drm_connector *c
 	if (!radeon_connector->dac_load_detect)
 		return ret;
 
-	r = pm_runtime_get_sync(connector->dev->dev);
-	if (r < 0)
-		return connector_status_disconnected;
+	if (!drm_kms_helper_is_poll_worker()) {
+		r = pm_runtime_get_sync(connector->dev->dev);
+		if (r < 0)
+			return connector_status_disconnected;
+	}
 
 	encoder = radeon_best_single_encoder(connector);
 	if (!encoder)

@@ -1167,8 +1179,12 @@ radeon_tv_detect(struct drm_connector *c
 	if (ret == connector_status_connected)
 		ret = radeon_connector_analog_encoder_conflict_solve(connector, encoder, ret, false);
 	radeon_connector_update_scratch_regs(connector, ret);
-	pm_runtime_mark_last_busy(connector->dev->dev);
-	pm_runtime_put_autosuspend(connector->dev->dev);
+
+	if (!drm_kms_helper_is_poll_worker()) {
+		pm_runtime_mark_last_busy(connector->dev->dev);
+		pm_runtime_put_autosuspend(connector->dev->dev);
+	}
+
 	return ret;
 }
 

@@ -1230,9 +1246,11 @@ radeon_dvi_detect(struct drm_connector *
 	enum drm_connector_status ret = connector_status_disconnected;
 	bool dret = false, broken_edid = false;
 
-	r = pm_runtime_get_sync(connector->dev->dev);
-	if (r < 0)
-		return connector_status_disconnected;
+	if (!drm_kms_helper_is_poll_worker()) {
+		r = pm_runtime_get_sync(connector->dev->dev);
+		if (r < 0)
+			return connector_status_disconnected;
+	}
 
 	if (radeon_connector->detected_hpd_without_ddc) {
 		force = true;

@@ -1415,8 +1433,10 @@ out:
 	}
 
 exit:
-	pm_runtime_mark_last_busy(connector->dev->dev);
-	pm_runtime_put_autosuspend(connector->dev->dev);
+	if (!drm_kms_helper_is_poll_worker()) {
+		pm_runtime_mark_last_busy(connector->dev->dev);
+		pm_runtime_put_autosuspend(connector->dev->dev);
+	}
 
 	return ret;
 }

@@ -1666,9 +1686,11 @@ radeon_dp_detect(struct drm_connector *c
 	if (radeon_dig_connector->is_mst)
 		return connector_status_disconnected;
 
-	r = pm_runtime_get_sync(connector->dev->dev);
-	if (r < 0)
-		return connector_status_disconnected;
+	if (!drm_kms_helper_is_poll_worker()) {
+		r = pm_runtime_get_sync(connector->dev->dev);
+		if (r < 0)
+			return connector_status_disconnected;
+	}
 
 	if (!force && radeon_check_hpd_status_unchanged(connector)) {
 		ret = connector->status;

@@ -1755,8 +1777,10 @@ radeon_dp_detect(struct drm_connector *c
 	}
 
 out:
-	pm_runtime_mark_last_busy(connector->dev->dev);
-	pm_runtime_put_autosuspend(connector->dev->dev);
+	if (!drm_kms_helper_is_poll_worker()) {
+		pm_runtime_mark_last_busy(connector->dev->dev);
+		pm_runtime_put_autosuspend(connector->dev->dev);
+	}
 
 	return ret;
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/workqueue-allow-retrieval-of-current-task-s-work-struct.patch queue-4.4/drm-radeon-fix-deadlock-on-runtime-suspend.patch queue-4.4/drm-amdgpu-fix-deadlock-on-runtime-suspend.patch queue-4.4/drm-allow-determining-if-current-task-is-output-poll-worker.patch queue-4.4/drm-nouveau-fix-deadlock-on-runtime-suspend.patch