[PATCH 1/8] sync_file: add type/flags to sync file object creation.

[Dave Airlie <airlied-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

From: Dave Airlie <airlied@redhat.com>

This allows us to create sync files with different semantics,
and clearly define the interoperation between them it also
provides flags to allow for tweaks on those semantics.

This provides a validation interface for drivers that accept
types from userspace so they can return EINVAL instead of ENOMEM.

This provides an ioctl for userspace to retrieve the type/flags
of an object it may recieve from somewhere else.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
---
 Documentation/driver-api/dma-buf.rst |  6 ++++
 drivers/dma-buf/sw_sync.c            |  2 +-
 drivers/dma-buf/sync_file.c          | 67 +++++++++++++++++++++++++++++++++---
 drivers/gpu/drm/drm_atomic.c         |  2 +-
 include/linux/sync_file.h            |  9 ++++-
 include/uapi/linux/sync_file.h       | 27 +++++++++++++++
 6 files changed, 106 insertions(+), 7 deletions(-)

diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst
index 31671b4..bf2f7d5 100644
--- a/Documentation/driver-api/dma-buf.rst
+++ b/Documentation/driver-api/dma-buf.rst
@@ -163,3 +163,9 @@ DMA Fence uABI/Sync File
 .. kernel-doc:: include/linux/sync_file.h
    :internal:
 
+
+Sync File IOCTL Definitions
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: include/uapi/linux/sync_file.h
+   :internal:
diff --git a/drivers/dma-buf/sw_sync.c b/drivers/dma-buf/sw_sync.c
index 69c5ff3..1c47de6 100644
--- a/drivers/dma-buf/sw_sync.c
+++ b/drivers/dma-buf/sw_sync.c
@@ -315,7 +315,7 @@ static long sw_sync_ioctl_create_fence(struct sync_timeline *obj,
 		goto err;
 	}
 
-	sync_file = sync_file_create(&pt->base);
+	sync_file = sync_file_create(&pt->base, SYNC_FILE_TYPE_FENCE, 0);
 	dma_fence_put(&pt->base);
 	if (!sync_file) {
 		err = -ENOMEM;
diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
index 2321035..4342d92 100644
--- a/drivers/dma-buf/sync_file.c
+++ b/drivers/dma-buf/sync_file.c
@@ -28,9 +28,32 @@
 
 static const struct file_operations sync_file_fops;
 
-static struct sync_file *sync_file_alloc(void)
+/**
+ * sync_file_validate_type_flags - validate type/flags for support
+ * @type: type of sync file object
+ * @flags: flags to sync object.
+ *
+ * Validates the flags are correct so userspace can get a more
+ * detailed error type.
+ */
+int sync_file_validate_type_flags(uint32_t type, uint32_t flags)
+{
+	if (flags)
+		return -EINVAL;
+	if (type != SYNC_FILE_TYPE_FENCE)
+		return -EINVAL;
+	return 0;
+}
+EXPORT_SYMBOL(sync_file_validate_type_flags);
+
+static struct sync_file *sync_file_alloc(uint32_t type, uint32_t flags)
 {
 	struct sync_file *sync_file;
+	int ret;
+
+	ret = sync_file_validate_type_flags(type, flags);
+	if (ret)
+		return NULL;
 
 	sync_file = kzalloc(sizeof(*sync_file), GFP_KERNEL);
 	if (!sync_file)
@@ -47,6 +70,8 @@ static struct sync_file *sync_file_alloc(void)
 
 	INIT_LIST_HEAD(&sync_file->cb.node);
 
+	sync_file->type = type;
+	sync_file->flags = flags;
 	return sync_file;
 
 err:
@@ -66,17 +91,21 @@ static void fence_check_cb_func(struct dma_fence *f, struct dma_fence_cb *cb)
 /**
  * sync_file_create() - creates a sync file
  * @fence:	fence to add to the sync_fence
+ * @type: type of sync file to create
+ * @flags: flags to create sync file with.
  *
  * Creates a sync_file containg @fence. This function acquires and additional
  * reference of @fence for the newly-created &sync_file, if it succeeds. The
  * sync_file can be released with fput(sync_file->file). Returns the
  * sync_file or NULL in case of error.
  */
-struct sync_file *sync_file_create(struct dma_fence *fence)
+struct sync_file *sync_file_create(struct dma_fence *fence,
+				   uint32_t type,
+				   uint32_t flags)
 {
 	struct sync_file *sync_file;
 
-	sync_file = sync_file_alloc();
+	sync_file = sync_file_alloc(type, flags);
 	if (!sync_file)
 		return NULL;
 
@@ -200,7 +229,7 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
 	struct dma_fence **fences, **nfences, **a_fences, **b_fences;
 	int i, i_a, i_b, num_fences, a_num_fences, b_num_fences;
 
-	sync_file = sync_file_alloc();
+	sync_file = sync_file_alloc(a->type, a->flags);
 	if (!sync_file)
 		return NULL;
 
@@ -339,6 +368,12 @@ static long sync_file_ioctl_merge(struct sync_file *sync_file,
 	}
 
 	data.name[sizeof(data.name) - 1] = '\0';
+
+	if (sync_file->type != fence2->type) {
+		err = -EINVAL;
+		goto err_put_fd;
+	}
+
 	fence3 = sync_file_merge(data.name, sync_file, fence2);
 	if (!fence3) {
 		err = -ENOMEM;
@@ -437,6 +472,27 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
 	return ret;
 }
 
+static long sync_file_ioctl_type(struct sync_file *sync_file,
+				 unsigned long arg)
+{
+	struct sync_file_type type;
+	int ret;
+	if (copy_from_user(&type, (void __user *)arg, sizeof(type)))
+		return -EFAULT;
+
+	if (type.flags || type.type)
+		return -EINVAL;
+
+	type.type = sync_file->type;
+	type.flags = sync_file->flags;
+
+	if (copy_to_user((void __user *)arg, &type, sizeof(type)))
+		ret = -EFAULT;
+	else
+		ret = 0;
+	return ret;
+}
+
 static long sync_file_ioctl(struct file *file, unsigned int cmd,
 			    unsigned long arg)
 {
@@ -449,6 +505,9 @@ static long sync_file_ioctl(struct file *file, unsigned int cmd,
 	case SYNC_IOC_FILE_INFO:
 		return sync_file_ioctl_fence_info(sync_file, arg);
 
+	case SYNC_IOC_TYPE:
+		return sync_file_ioctl_type(sync_file, arg);
+
 	default:
 		return -ENOTTY;
 	}
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index a567310..bb5a740 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -1917,7 +1917,7 @@ static int setup_out_fence(struct drm_out_fence_state *fence_state,
 	if (put_user(fence_state->fd, fence_state->out_fence_ptr))
 		return -EFAULT;
 
-	fence_state->sync_file = sync_file_create(fence);
+	fence_state->sync_file = sync_file_create(fence, SYNC_FILE_TYPE_FENCE, 0);
 	if (!fence_state->sync_file)
 		return -ENOMEM;
 
diff --git a/include/linux/sync_file.h b/include/linux/sync_file.h
index 3e3ab84..ede4182 100644
--- a/include/linux/sync_file.h
+++ b/include/linux/sync_file.h
@@ -20,6 +20,8 @@
 #include <linux/spinlock.h>
 #include <linux/dma-fence.h>
 #include <linux/dma-fence-array.h>
+#include <uapi/linux/sync_file.h>
+
 
 /**
  * struct sync_file - sync file to export to the userspace
@@ -30,6 +32,8 @@
  * @wq:			wait queue for fence signaling
  * @fence:		fence with the fences in the sync_file
  * @cb:			fence callback information
+ * @type:               sync file type
+ * @flags:              flags used to create sync file
  */
 struct sync_file {
 	struct file		*file;
@@ -43,11 +47,14 @@ struct sync_file {
 
 	struct dma_fence	*fence;
 	struct dma_fence_cb cb;
+	uint32_t type;
+	uint32_t flags;
 };
 
 #define POLL_ENABLED DMA_FENCE_FLAG_USER_BITS
 
-struct sync_file *sync_file_create(struct dma_fence *fence);
+int sync_file_validate_type_flags(uint32_t type, uint32_t flags);
+struct sync_file *sync_file_create(struct dma_fence *fence, uint32_t type, uint32_t flags);
 struct dma_fence *sync_file_get_fence(int fd);
 
 #endif /* _LINUX_SYNC_H */
diff --git a/include/uapi/linux/sync_file.h b/include/uapi/linux/sync_file.h
index 5b287d6..f439cda 100644
--- a/include/uapi/linux/sync_file.h
+++ b/include/uapi/linux/sync_file.h
@@ -69,6 +69,26 @@ struct sync_file_info {
 #define SYNC_IOC_MAGIC		'>'
 
 /**
+ * DOC: SYNC_FILE_TYPE_FENCE - fence sync file object
+ *
+ * This sync file is a wrapper around a dma fence or a dma fence array.
+ * It can be merged with another fence sync file object to create a new
+ * merged object.
+ * The fence backing this object cannot be replaced.
+ * This is useful for shared fences.
+ */
+#define SYNC_FILE_TYPE_FENCE 0
+
+/**
+ * struct sync_file_type - data returned from sync file type ioctl
+ * @type:	sync_file type
+ * @flags:	sync_file creation flags
+ */
+struct sync_file_type {
+	__u32	type;
+	__u32	flags;
+};
+/**
  * Opcodes  0, 1 and 2 were burned during a API change to avoid users of the
  * old API to get weird errors when trying to handling sync_files. The API
  * change happened during the de-stage of the Sync Framework when there was
@@ -94,4 +114,11 @@ struct sync_file_info {
  */
 #define SYNC_IOC_FILE_INFO	_IOWR(SYNC_IOC_MAGIC, 4, struct sync_file_info)
 
+/**
+ * DOC: SYNC_IOC_TYPE - get creation type and flags of sync_file.
+ *
+ * Takes a struct sync_file_type. Returns the created values of type and flags.
+ */
+#define SYNC_IOC_TYPE		_IOWR(SYNC_IOC_MAGIC, 5, struct sync_file_type)
+
 #endif /* _UAPI_LINUX_SYNC_H */
-- 
2.9.3

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