Merge "msm: kgsl: Use worker to put refcount on mem entry"

drivers/gpu/msm/kgsl.c

@@ -248,6 +248,13 @@ static void _deferred_put(struct work_struct *work)
 	kgsl_mem_entry_put(entry);
 }
 
+/* Use a worker to put the refcount on mem entry */
+void kgsl_mem_entry_put_deferred(struct kgsl_mem_entry *entry)
+{
+	INIT_WORK(&entry->work, _deferred_put);
+	queue_work(kgsl_driver.mem_workqueue, &entry->work);
+}
+
 static struct kgsl_mem_entry *kgsl_mem_entry_create(void)
 {
 	struct kgsl_mem_entry *entry = kzalloc(sizeof(*entry), GFP_KERNEL);
@@ -2336,8 +2343,7 @@ static bool gpuobj_free_fence_func(void *priv)
 			entry->memdesc.gpuaddr, entry->memdesc.size,
 			entry->memdesc.flags);
 
-	INIT_WORK(&entry->work, _deferred_put);
-	queue_work(kgsl_driver.mem_workqueue, &entry->work);
+	kgsl_mem_entry_put_deferred(entry);
 	return true;
 }
 

drivers/gpu/msm/kgsl.h

@@ -561,6 +561,13 @@ kgsl_mem_entry_put(struct kgsl_mem_entry *entry)
 		kref_put(&entry->refcount, kgsl_mem_entry_destroy);
 }
 
+/**
+ * kgsl_mem_entry_put_deferred() - use a worker to put the refcount
+ * on mem entry from a sysfs handler or debugfs handler.
+ * @entry - The memory entry
+ */
+void kgsl_mem_entry_put_deferred(struct kgsl_mem_entry *entry);
+
 /*
  * kgsl_addr_range_overlap() - Checks if 2 ranges overlap
  * @gpuaddr1: Start of first address range

drivers/gpu/msm/kgsl_sharedmem.c

@@ -136,7 +136,18 @@ imported_mem_show(struct kgsl_process_private *priv,
 			}
 		}
 
-		kgsl_mem_entry_put(entry);
+		/*
+		 * If refcount on mem entry is the last refcount, we will
+		 * call kgsl_mem_entry_destroy and detach it from process
+		 * list. When there is no refcount on the process private,
+		 * we will call kgsl_destroy_process_private to do cleanup.
+		 * During cleanup, we will try to remove the same sysfs
+		 * node which is in use by the current thread and this
+		 * situation will end up in a deadloack.
+		 * To avoid this situation, use a worker to put the refcount
+		 * on mem entry.
+		 */
+		kgsl_mem_entry_put_deferred(entry);
 		spin_lock(&priv->mem_lock);
 	}
 	spin_unlock(&priv->mem_lock);
@@ -227,12 +238,6 @@ static ssize_t memtype_sysfs_show(struct kobject *kobj,
 	u64 size = 0;
 	int id = 0;
 
-	/*
-	 * sysfs_remove_file waits for reads to complete before the node is
-	 * deleted and process private is freed only once kobj is released.
-	 * This implies that priv will not be freed until this function
-	 * completes, and no further locking is needed.
-	 */
 	priv = container_of(kobj, struct kgsl_process_private, kobj_memtype);
 	memtype = container_of(attr, struct kgsl_memtype, attr);
 
@@ -253,7 +258,7 @@ static ssize_t memtype_sysfs_show(struct kobject *kobj,
 		if (type == memtype->type)
 			size += memdesc->size;
 
-		kgsl_mem_entry_put(entry);
+		kgsl_mem_entry_put_deferred(entry);
 		spin_lock(&priv->mem_lock);
 	}
 	spin_unlock(&priv->mem_lock);