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Patch "drm/amdgpu: Fix deadlock on runtime suspend" has been added to the 4.9-stable tree

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

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Stable branch DRM drivers Radeon and amdgpu DRM drivers
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This is a note to let you know that I've just added the patch titled

drm/amdgpu: Fix deadlock on runtime suspend

to the 4.9-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-amdgpu-fix-deadlock-on-runtime-suspend.patch
and it can be found in the queue-4.9 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 aa0aad57909eb321746325951d66af88a83bc956 Mon Sep 17 00:00:00 2001

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

From: Lukas Wunner <[email protected]>

commit aa0aad57909eb321746325951d66af88a83bc956 upstream.

amdgpu'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 amdgpu'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.

Fixes d38ceaf99ed0 ("drm/amdgpu: add core driver (v4)")
Cc [email protected] # v4.2+: 27d4ee03078a: workqueue: Allow retrieval of current task's work struct
Cc [email protected] # v4.2+: 25c058ccaf2e: drm: Allow determining if current task is output poll worker
Cc Alex Deucher <[email protected]>
Tested-by Mike Lothian <[email protected]>
Reviewed-by Lyude Paul <[email protected]>
Signed-off-by Lukas Wunner <[email protected]>
Link https://patchwork.freedesktop.org/patch/msgid/4c9bf72aacae1eef062bd134cd112e0770a7f121.1518338789.git.lukas@wunner.de
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c |   58 ++++++++++++++++---------
 1 file changed, 38 insertions(+), 20 deletions(-)
drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c +38 -20
@@ -739,9 +739,11 @@ amdgpu_connector_lvds_detect(struct drm_
 	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 amdgpu_encoder *amdgpu_encoder = to_amdgpu_encoder(encoder);

@@ -760,8 +762,12 @@ amdgpu_connector_lvds_detect(struct drm_
 	/* check acpi lid status ??? */
 
 	amdgpu_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;
 }
 

@@ -871,9 +877,11 @@ amdgpu_connector_vga_detect(struct drm_c
 	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 = amdgpu_connector_best_single_encoder(connector);
 	if (!encoder)

@@ -927,8 +935,10 @@ amdgpu_connector_vga_detect(struct drm_c
 	amdgpu_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;
 }

@@ -991,9 +1001,11 @@ amdgpu_connector_dvi_detect(struct drm_c
 	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 (!force && amdgpu_connector_check_hpd_status_unchanged(connector)) {
 		ret = connector->status;

@@ -1118,8 +1130,10 @@ out:
 	amdgpu_connector_update_scratch_regs(connector, ret);
 
 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;
 }

@@ -1362,9 +1376,11 @@ amdgpu_connector_dp_detect(struct drm_co
 	struct drm_encoder *encoder = amdgpu_connector_best_single_encoder(connector);
 	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 (!force && amdgpu_connector_check_hpd_status_unchanged(connector)) {
 		ret = connector->status;

@@ -1432,8 +1448,10 @@ amdgpu_connector_dp_detect(struct drm_co
 
 	amdgpu_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;
 }

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

queue-4.9/workqueue-allow-retrieval-of-current-task-s-work-struct.patch queue-4.9/drm-radeon-fix-deadlock-on-runtime-suspend.patch queue-4.9/drm-amdgpu-fix-deadlock-on-runtime-suspend.patch queue-4.9/drm-allow-determining-if-current-task-is-output-poll-worker.patch queue-4.9/drm-nouveau-fix-deadlock-on-runtime-suspend.patch