From 1c92a85bdb460cee779c207999faf16c7ecdd196 Mon Sep 17 00:00:00 2001
From: Thomas Hellstrom <thomas-at-tungstengraphics-dot-com>
Date: Sat, 1 Mar 2008 17:01:57 +0100
Subject: [PATCH] Copy back buffer validate replies immediately after validation succeeds.

If we hit an -EAGAIN, restore the original buffer validate arguments.
---
 shared-core/i915_dma.c |   77 ++++++++++++++++++++++++++++++++++--------------
 1 files changed, 55 insertions(+), 22 deletions(-)

diff --git a/shared-core/i915_dma.c b/shared-core/i915_dma.c
index f9e02c7..eda9570 100644
--- a/shared-core/i915_dma.c
+++ b/shared-core/i915_dma.c
@@ -810,10 +810,9 @@ struct i915_relocatee_info {
 
 struct drm_i915_validate_buffer {
 	struct drm_buffer_object *buffer;
-	struct drm_bo_info_rep rep;
+	struct drm_bo_op_req req;
 	int presumed_offset_correct;
 	void __user *data;
-	int ret;
 };
 
 static void i915_dereference_buffers_locked(struct drm_i915_validate_buffer *buffers,
@@ -1071,6 +1070,7 @@ int i915_validate_buffer_list(struct drm
 {
 	struct drm_i915_op_arg arg;
 	struct drm_bo_op_req *req = &arg.d.req;
+	struct drm_bo_arg_rep rep;
 	int ret = 0;
 	unsigned buf_count = 0;
 	uint32_t buf_handle;
@@ -1078,31 +1078,31 @@ int i915_validate_buffer_list(struct drm
 	struct drm_i915_validate_buffer *item = buffers;
 
 	do {
+		item = buffers + buf_count;
+		item->data = (void __user *) (unsigned long) data;
+		item->buffer = NULL;
+		item->presumed_offset_correct = 0;
+
 		if (buf_count >= *num_buffers) {
 			DRM_ERROR("Buffer count exceeded %d\n.", *num_buffers);
 			ret = -EINVAL;
 			goto out_err;
 		}
-		item = buffers + buf_count;
-		item->buffer = NULL;
-		item->presumed_offset_correct = 0;
 
 		buffers[buf_count].buffer = NULL;
 
 		if (copy_from_user(&arg, (void __user *)(unsigned long)data, sizeof(arg))) {
 			ret = -EFAULT;
-			goto out_err;
+			goto out_err_copy;
 		}
-
 		ret = 0;
+
 		if (req->op != drm_bo_validate) {
 			DRM_ERROR
 			    ("Buffer object operation wasn't \"validate\".\n");
 			ret = -EINVAL;
-			goto out_err;
+			goto out_err_copy;
 		}
-		item->ret = 0;
-		item->data = (void __user *) (unsigned long) data;
 
 		buf_handle = req->bo_req.handle;
 		reloc_user_ptr = (uint32_t *)(unsigned long)arg.reloc_ptr;
@@ -1114,32 +1114,52 @@ int i915_validate_buffer_list(struct drm
 			DRM_MEMORYBARRIER();
 		}
 
+		arg.handled = 1;
 		ret = drm_bo_handle_validate(file_priv, req->bo_req.handle,
 					     req->bo_req.flags, req->bo_req.mask,
 					     req->bo_req.hint,
 					     req->bo_req.fence_class, 0,
-					     &item->rep,
+					     &rep.bo_info,
 					     &item->buffer);
 
 		if (ret) {
 			DRM_ERROR("error on handle validate %d\n", ret);
-			goto out_err;
+			goto out_err_copy;
 		}
 
+		item->req = *req;
 		buf_count++;
+		rep.ret = 0;
 
 		ret = i915_check_presumed(&arg, item->buffer,
 					  (uint32_t __user *)
 					  (unsigned long) data,
 					  &item->presumed_offset_correct);
+		arg.d.rep = rep;
+		if (ret)
+			goto out_err;
+
+		ret = __copy_to_user(item->data, &arg, sizeof(arg));
 		if (ret)
 			goto out_err;
 
 		data = arg.next;
 	} while (data != 0);
+
+out_err_copy:
+
+	/*
+	 * Buffer specific error.
+	 */
+
+	if (ret && (ret != -EAGAIN)) {
+		rep.ret = ret;
+		arg.handled = 1;
+	        if (__copy_to_user(item->data, &arg, sizeof(arg)))
+			ret = -EFAULT;
+	}
 out_err:
 	*num_buffers = buf_count;
-	item->ret = (ret != -EAGAIN) ? ret : 0;
 	return ret;
 }
 
@@ -1149,8 +1169,8 @@ out_err:
  * If the execbuffer operation was aborted, for example due to a signal,
  * this also make sure that buffers retain their original state and
  * fence pointers.
- * Copy back buffer information to user-space unless we were interrupted
- * by a signal. In which case the IOCTL must be rerun.
+ * Restore the origininal IOCTL arguments in case we've hit an EAGAIN and
+ * the IOCTL needs to be rerun.
  */
 
 static int i915_handle_copyback(struct drm_device *dev,
@@ -1159,17 +1179,30 @@ static int i915_handle_copyback(struct d
 {
 	int err = ret;
 	int i;
-	struct drm_i915_op_arg arg;
-
+	uint8_t __user *user_req;
 	if (ret)
 		drm_putback_buffer_objects(dev);
 
-	if (ret != -EAGAIN) {
+	if (ret == -EAGAIN) {
 		for (i = 0; i < num_buffers; ++i) {
-			arg.handled = 1;
-			arg.d.rep.ret = buffers->ret;
-			arg.d.rep.bo_info = buffers->rep;
-			if (__copy_to_user(buffers->data, &arg, sizeof(arg)))
+
+			/*
+			 * Set arg.handled to zero.
+			 */
+
+			user_req = buffers->data;
+			user_req += offsetof(struct drm_i915_op_arg, handled);
+			if (__put_user(0, (int __user *)user_req))
+				err = -EFAULT;
+
+			/*
+			 * Restore the original arg.d.req member.
+			 */
+
+			user_req = buffers->data;
+			user_req += offsetof(struct drm_i915_op_arg, d.req);
+			if (__copy_to_user(user_req, &buffers->req,
+					   sizeof(buffers->req)))
 				err = -EFAULT;
 			buffers++;
 		}
-- 
1.4.1