[PATCH] drm: fix call_kern.cocci warnings v3

[Chunming Zhou <david1.zhou@xxxxxxx>]

drivers/gpu/drm/drm_syncobj.c:202:4-14: ERROR: function drm_syncobj_find_signal_pt_for_point called on line 390 inside lock on line 389 but uses GFP_KERNEL

  Find functions that refer to GFP_KERNEL but are called with locks held.

Generated by: scripts/coccinelle/locks/call_kern.cocci

v2:
syncobj->timeline still needs protect.

v3:
use a global signaled fence instead of re-allocation.

Signed-off-by: Chunming Zhou <david1.zhou@xxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
Cc: Christian König <easy2remember.chk@xxxxxxxxxxxxxx>
---
 drivers/gpu/drm/drm_drv.c     |  2 ++
 drivers/gpu/drm/drm_syncobj.c | 52 +++++++++++++++++++++--------------
 include/drm/drm_syncobj.h     |  1 +
 3 files changed, 34 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 36e8e9cbec52..0a6f1023d6c3 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -37,6 +37,7 @@
 #include <drm/drm_client.h>
 #include <drm/drm_drv.h>
 #include <drm/drmP.h>
+#include <drm/drm_syncobj.h>
 
 #include "drm_crtc_internal.h"
 #include "drm_legacy.h"
@@ -1003,6 +1004,7 @@ static int __init drm_core_init(void)
 	if (ret < 0)
 		goto error;
 
+	drm_syncobj_stub_fence_init();
 	drm_core_init_complete = true;
 
 	DRM_DEBUG("Initialized\n");
diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index b7eaa603f368..6b3f5a06e4d3 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -80,6 +80,27 @@ struct drm_syncobj_signal_pt {
 	struct list_head list;
 };
 
+static struct drm_syncobj_stub_fence stub_signaled_fence;
+static void global_stub_fence_release(struct dma_fence *fence)
+{
+	/* it is impossible to come here */
+	BUG();
+}
+static const struct dma_fence_ops global_stub_fence_ops = {
+	.get_driver_name = drm_syncobj_stub_fence_get_name,
+	.get_timeline_name = drm_syncobj_stub_fence_get_name,
+	.release = global_stub_fence_release,
+};
+
+void drm_syncobj_stub_fence_init(void)
+{
+	spin_lock_init(&stub_signaled_fence.lock);
+	dma_fence_init(&stub_signaled_fence.base,
+		       &global_stub_fence_ops,
+		       &stub_signaled_fence.lock,
+		       0, 0);
+	dma_fence_signal(&stub_signaled_fence.base);
+}
 /**
  * drm_syncobj_find - lookup and reference a sync object.
  * @file_private: drm file private pointer
@@ -111,24 +132,14 @@ static struct dma_fence
 				      uint64_t point)
 {
 	struct drm_syncobj_signal_pt *signal_pt;
+	struct dma_fence *f = NULL;
 
+	spin_lock(&syncobj->pt_lock);
 	if ((syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) &&
 	    (point <= syncobj->timeline)) {
-		struct drm_syncobj_stub_fence *fence =
-			kzalloc(sizeof(struct drm_syncobj_stub_fence),
-				GFP_KERNEL);
-
-		if (!fence)
-			return NULL;
-		spin_lock_init(&fence->lock);
-		dma_fence_init(&fence->base,
-			       &drm_syncobj_stub_fence_ops,
-			       &fence->lock,
-			       syncobj->timeline_context,
-			       point);
-
-		dma_fence_signal(&fence->base);
-		return &fence->base;
+		dma_fence_get(&stub_signaled_fence.base);
+		spin_unlock(&syncobj->pt_lock);
+		return &stub_signaled_fence.base;
 	}
 
 	list_for_each_entry(signal_pt, &syncobj->signal_pt_list, list) {
@@ -137,9 +148,12 @@ static struct dma_fence
 		if ((syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) &&
 		    (point != signal_pt->value))
 			continue;
-		return dma_fence_get(&signal_pt->fence_array->base);
+		f = dma_fence_get(&signal_pt->fence_array->base);
+		break;
 	}
-	return NULL;
+	spin_unlock(&syncobj->pt_lock);
+
+	return f;
 }
 
 static void drm_syncobj_add_callback_locked(struct drm_syncobj *syncobj,
@@ -166,9 +180,7 @@ static void drm_syncobj_fence_get_or_add_callback(struct drm_syncobj *syncobj,
 	}
 
 	mutex_lock(&syncobj->cb_mutex);
-	spin_lock(&syncobj->pt_lock);
 	*fence = drm_syncobj_find_signal_pt_for_point(syncobj, pt_value);
-	spin_unlock(&syncobj->pt_lock);
 	if (!*fence)
 		drm_syncobj_add_callback_locked(syncobj, cb, func);
 	mutex_unlock(&syncobj->cb_mutex);
@@ -379,11 +391,9 @@ drm_syncobj_point_get(struct drm_syncobj *syncobj, u64 point, u64 flags,
 		if (ret < 0)
 			return ret;
 	}
-	spin_lock(&syncobj->pt_lock);
 	*fence = drm_syncobj_find_signal_pt_for_point(syncobj, point);
 	if (!*fence)
 		ret = -EINVAL;
-	spin_unlock(&syncobj->pt_lock);
 	return ret;
 }
 
diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h
index 29244cbcd05e..63cfd1540241 100644
--- a/include/drm/drm_syncobj.h
+++ b/include/drm/drm_syncobj.h
@@ -148,4 +148,5 @@ int drm_syncobj_get_fd(struct drm_syncobj *syncobj, int *p_fd);
 int drm_syncobj_search_fence(struct drm_syncobj *syncobj, u64 point, u64 flags,
 			     struct dma_fence **fence);
 
+void drm_syncobj_stub_fence_init(void);
 #endif
-- 
2.17.1

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