FAILED: patch "[PATCH] drm/radeon: Fix deadlock on runtime suspend" failed to apply to 4.14-stable tree

PATCH [email protected] 1 participant 1 message Feb 26, 2018

Subsystems (3)

Stable branch DRM drivers Radeon and amdgpu DRM drivers

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2018-02-26 16:07 UTC #0 lore raw

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

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: [PATCH] drm/radeon: Fix deadlock on runtime suspend

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

drivers/gpu/drm/radeon/radeon_connectors.c +49 ~~-25~~

index 59dcefb2df3b..30e129684c7c 100644
@@ -900,9 +900,11 @@ radeon_lvds_detect(struct drm_connector *connector, bool force)
 	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);

@@ -925,8 +927,12 @@ radeon_lvds_detect(struct drm_connector *connector, bool force)
 	/* 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;
 }

@@ -1040,9 +1046,11 @@ radeon_vga_detect(struct drm_connector *connector, bool force)
 	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)

@@ -1109,8 +1117,10 @@ radeon_vga_detect(struct drm_connector *connector, bool force)
 	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;
 }

@@ -1174,9 +1184,11 @@ radeon_tv_detect(struct drm_connector *connector, bool force)
 	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)

@@ -1188,8 +1200,12 @@ radeon_tv_detect(struct drm_connector *connector, bool force)
 	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;
 }

@@ -1252,9 +1268,11 @@ radeon_dvi_detect(struct drm_connector *connector, bool force)
 	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;

@@ -1437,8 +1455,10 @@ radeon_dvi_detect(struct drm_connector *connector, bool force)
 	}
 
 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;
 }

@@ -1689,9 +1709,11 @@ radeon_dp_detect(struct drm_connector *connector, bool force)
 	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;

@@ -1778,8 +1800,10 @@ radeon_dp_detect(struct drm_connector *connector, bool force)
 	}
 
 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;
 }