[PATCH] drm/i915/guc: Don't take struct_mutex for object unreference

[PATCH] drm/i915/guc: Don't take struct_mutex for object unreference

[Chris Wilson]

We no longer need to take the struct_mutex for freeing objects, and on
the finalisation paths here the mutex is not been used for serialisation
of the pointer access, so remove the BKL wart.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_guc_loader.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_guc_loader.c b/drivers/gpu/drm/i915/intel_guc_loader.c
index 1aa85236b788..77a5c27b9da0 100644
--- a/drivers/gpu/drm/i915/intel_guc_loader.c
+++ b/drivers/gpu/drm/i915/intel_guc_loader.c
@@ -699,12 +699,9 @@ static void guc_fw_fetch(struct drm_device *dev, struct intel_guc_fw *guc_fw)
 	DRM_DEBUG_DRIVER("GuC fw fetch status FAIL; err %d, fw %p, obj %p\n",
 		err, fw, guc_fw->guc_fw_obj);
 
-	mutex_lock(&dev->struct_mutex);
-	obj = guc_fw->guc_fw_obj;
+	obj = fetch_and_zero(&guc_fw->guc_fw_obj);
 	if (obj)
 		i915_gem_object_put(obj);
-	guc_fw->guc_fw_obj = NULL;
-	mutex_unlock(&dev->struct_mutex);
 
 	release_firmware(fw);		/* OK even if fw is NULL */
 	guc_fw->guc_fw_fetch_status = GUC_FIRMWARE_FAIL;
@@ -781,16 +778,17 @@ void intel_guc_fini(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct intel_guc_fw *guc_fw = &dev_priv->guc.guc_fw;
+	struct drm_i915_gem_object *obj;
 
 	mutex_lock(&dev->struct_mutex);
 	guc_interrupts_release(dev_priv);
 	i915_guc_submission_disable(dev_priv);
 	i915_guc_submission_fini(dev_priv);
-
-	if (guc_fw->guc_fw_obj)
-		i915_gem_object_put(guc_fw->guc_fw_obj);
-	guc_fw->guc_fw_obj = NULL;
 	mutex_unlock(&dev->struct_mutex);
 
+	obj = fetch_and_zero(&guc_fw->guc_fw_obj);
+	if (obj)
+		i915_gem_object_put(obj);
+
 	guc_fw->guc_fw_fetch_status = GUC_FIRMWARE_NONE;
 }
-- 
2.10.2

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[PATCH] drm/i915/guc: Don't take struct_mutex for object unreference

[Chris Wilson]

We no longer need to take the struct_mutex for freeing objects, and on
the finalisation paths here the mutex is not been used for serialisation
of the pointer access, so remove the BKL wart.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_guc_loader.c | 14 ++++++--------
 drivers/gpu/drm/i915/intel_huc.c        |  9 ++++-----
 2 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_guc_loader.c b/drivers/gpu/drm/i915/intel_guc_loader.c
index 8ef33d88d5a0..9885f760f2ef 100644
--- a/drivers/gpu/drm/i915/intel_guc_loader.c
+++ b/drivers/gpu/drm/i915/intel_guc_loader.c
@@ -714,12 +714,9 @@ void intel_uc_fw_fetch(struct drm_i915_private *dev_priv,
 	DRM_DEBUG_DRIVER("uC fw fetch status FAIL; err %d, fw %p, obj %p\n",
 		err, fw, uc_fw->obj);
 
-	mutex_lock(&dev_priv->drm.struct_mutex);
-	obj = uc_fw->obj;
+	obj = fetch_and_zero(&uc_fw->obj);
 	if (obj)
 		i915_gem_object_put(obj);
-	uc_fw->obj = NULL;
-	mutex_unlock(&dev_priv->drm.struct_mutex);
 
 	release_firmware(fw);		/* OK even if fw is NULL */
 	uc_fw->fetch_status = INTEL_UC_FIRMWARE_FAIL;
@@ -793,16 +790,17 @@ void intel_guc_init(struct drm_i915_private *dev_priv)
 void intel_guc_fini(struct drm_i915_private *dev_priv)
 {
 	struct intel_uc_fw *guc_fw = &dev_priv->guc.fw;
+	struct drm_i915_gem_object *obj;
 
 	mutex_lock(&dev_priv->drm.struct_mutex);
 	guc_interrupts_release(dev_priv);
 	i915_guc_submission_disable(dev_priv);
 	i915_guc_submission_fini(dev_priv);
-
-	if (guc_fw->obj)
-		i915_gem_object_put(guc_fw->obj);
-	guc_fw->obj = NULL;
 	mutex_unlock(&dev_priv->drm.struct_mutex);
 
+	obj = fetch_and_zero(&guc_fw->obj);
+	if (obj)
+		i915_gem_object_put(obj);
+
 	guc_fw->fetch_status = INTEL_UC_FIRMWARE_NONE;
 }
diff --git a/drivers/gpu/drm/i915/intel_huc.c b/drivers/gpu/drm/i915/intel_huc.c
index c144609425f6..c28543d220a2 100644
--- a/drivers/gpu/drm/i915/intel_huc.c
+++ b/drivers/gpu/drm/i915/intel_huc.c
@@ -274,12 +274,11 @@ int intel_huc_load(struct drm_i915_private *dev_priv)
 void intel_huc_fini(struct drm_i915_private *dev_priv)
 {
 	struct intel_uc_fw *huc_fw = &dev_priv->huc.fw;
+	struct drm_i915_gem_object *obj;
 
-	mutex_lock(&dev_priv->drm.struct_mutex);
-	if (huc_fw->obj)
-		i915_gem_object_put(huc_fw->obj);
-	huc_fw->obj = NULL;
-	mutex_unlock(&dev_priv->drm.struct_mutex);
+	obj = fetch_and_zero(&huc_fw->obj);
+	if (obj)
+		i915_gem_object_put(obj);
 
 	huc_fw->fetch_status = INTEL_UC_FIRMWARE_NONE;
 }
-- 
2.11.0

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Re: [PATCH] drm/i915/guc: Don't take struct_mutex for object unreference

[Joonas Lahtinen]

On ti, 2017-02-14 at 13:34 +0000, Chris Wilson wrote:
> We no longer need to take the struct_mutex for freeing objects, and on
> the finalisation paths here the mutex is not been used for serialisation
> of the pointer access, so remove the BKL wart.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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✓ Fi.CI.BAT: success for drm/i915/guc: Don't take struct_mutex for object unreference (rev2)

[Patchwork]

== Series Details ==

Series: drm/i915/guc: Don't take struct_mutex for object unreference (rev2)
URL   : https://patchwork.freedesktop.org/series/15071/
State : success

== Summary ==

Series 15071v2 drm/i915/guc: Don't take struct_mutex for object unreference
https://patchwork.freedesktop.org/api/1.0/series/15071/revisions/2/mbox/

fi-bdw-5557u     total:252  pass:241  dwarn:0   dfail:0   fail:0   skip:11 
fi-bsw-n3050     total:252  pass:213  dwarn:0   dfail:0   fail:0   skip:39 
fi-bxt-j4205     total:252  pass:233  dwarn:0   dfail:0   fail:0   skip:19 
fi-bxt-t5700     total:83   pass:70   dwarn:0   dfail:0   fail:0   skip:12 
fi-byt-j1900     total:252  pass:225  dwarn:0   dfail:0   fail:0   skip:27 
fi-byt-n2820     total:252  pass:221  dwarn:0   dfail:0   fail:0   skip:31 
fi-hsw-4770      total:252  pass:236  dwarn:0   dfail:0   fail:0   skip:16 
fi-hsw-4770r     total:252  pass:236  dwarn:0   dfail:0   fail:0   skip:16 
fi-ilk-650       total:252  pass:202  dwarn:0   dfail:0   fail:0   skip:50 
fi-ivb-3520m     total:252  pass:234  dwarn:0   dfail:0   fail:0   skip:18 
fi-ivb-3770      total:252  pass:234  dwarn:0   dfail:0   fail:0   skip:18 
fi-kbl-7500u     total:252  pass:234  dwarn:0   dfail:0   fail:0   skip:18 
fi-skl-6260u     total:252  pass:242  dwarn:0   dfail:0   fail:0   skip:10 
fi-skl-6700hq    total:252  pass:235  dwarn:0   dfail:0   fail:0   skip:17 
fi-skl-6700k     total:252  pass:230  dwarn:4   dfail:0   fail:0   skip:18 
fi-skl-6770hq    total:252  pass:242  dwarn:0   dfail:0   fail:0   skip:10 
fi-snb-2520m     total:252  pass:224  dwarn:0   dfail:0   fail:0   skip:28 
fi-snb-2600      total:252  pass:223  dwarn:0   dfail:0   fail:0   skip:29 

7b80cb5504b3b3cebaea944d35f25e27415e89a6 drm-tip: 2017y-02m-14d-14h-36m-43s UTC integration manifest
c3d40c6 drm/i915/guc: Don't take struct_mutex for object unreference

== Logs ==

For more details see: https://intel-gfx-ci.01.org/CI/Patchwork_3806/
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