[PATCH 4.4 09/63] drm/amdgpu: Fix deadlock on runtime suspend

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

--

From: Lukas Wunner 

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: sta...@vger.kernel.org # v4.2+: 27d4ee03078a: workqueue: Allow retrieval of 
current task's work struct
Cc: sta...@vger.kernel.org # v4.2+: 25c058ccaf2e: drm: Allow determining if 
current task is output poll worker
Cc: Alex Deucher 
Tested-by: Mike Lothian 
Reviewed-by: Lyude Paul 
Signed-off-by: Lukas Wunner 
Link: 
https://patchwork.freedesktop.org/patch/msgid/4c9bf72aacae1eef062bd134cd112e0770a7f121.1518338789.git.lu...@wunner.de
Signed-off-by: Greg Kroah-Hartman 

---
 drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c |   58 -
 1 file changed, 38 insertions(+), 20 deletions(-)

--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
@@ -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;
 }
 
@@ -862,9 +868,11 @@ 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)
@@ -918,8 +926,10 @@ 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;
 }
@@ -981,9 +991,11 @@ 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;
@@ -1108,8 +1120,10 @@ 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;
 }
@@ -1351,9 +1365,11 @@ amdgpu_connector_dp_detect(struct drm_co
struct drm_encoder *encoder = 
amdgpu_connector_best_single_encoder(connector);
int r;
 
-   r = 

[PATCH 4.4 09/63] drm/amdgpu: Fix deadlock on runtime suspend

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

--

From: Lukas Wunner 

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: sta...@vger.kernel.org # v4.2+: 27d4ee03078a: workqueue: Allow retrieval of 
current task's work struct
Cc: sta...@vger.kernel.org # v4.2+: 25c058ccaf2e: drm: Allow determining if 
current task is output poll worker
Cc: Alex Deucher 
Tested-by: Mike Lothian 
Reviewed-by: Lyude Paul 
Signed-off-by: Lukas Wunner 
Link: 
https://patchwork.freedesktop.org/patch/msgid/4c9bf72aacae1eef062bd134cd112e0770a7f121.1518338789.git.lu...@wunner.de
Signed-off-by: Greg Kroah-Hartman 

---
 drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c |   58 -
 1 file changed, 38 insertions(+), 20 deletions(-)

--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
@@ -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;
 }
 
@@ -862,9 +868,11 @@ 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)
@@ -918,8 +926,10 @@ 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;
 }
@@ -981,9 +991,11 @@ 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;
@@ -1108,8 +1120,10 @@ 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;
 }
@@ -1351,9 +1365,11 @@ 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