Patch "drm/atomic: Handle -EDEADLK with out-fences correctly" has been added to the 4.12-stable tree

This is a note to let you know that I've just added the patch titled

drm/atomic: Handle -EDEADLK with out-fences correctly

to the 4.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-atomic-handle-edeadlk-with-out-fences-correctly.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Maarten Lankhorst <[email protected]>
Date: Mon, 14 Aug 2017 12:07:21 +0200
Subject: drm/atomic: Handle -EDEADLK with out-fences correctly

From: Maarten Lankhorst <[email protected]>

commit 7f5d6dac548b983702dd7aac1d463bd88dff50a8 upstream.

complete_crtc_signaling is freeing fence_state, but when retrying num_fences and fence_state are not zero'd. This caused duplicate fd's in the fence_state array, followed by a BUG_ON in fs/file.c because we reallocate freed memory, and installing over an existing fd, or potential other fun.

Zero fence_state and num_fences correctly in the retry loop, which allows kms_atomic_transition to pass.

Testcase: kms_atomic_transitions.plane-all-modeset-transition-fencing (with CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y)

---
 drivers/gpu/drm/drm_atomic.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

@@ -2093,10 +2093,10 @@ int drm_mode_atomic_ioctl(struct drm_dev
 	struct drm_atomic_state *state;
 	struct drm_modeset_acquire_ctx ctx;
 	struct drm_plane *plane;
-	struct drm_out_fence_state *fence_state = NULL;
+	struct drm_out_fence_state *fence_state;
 	unsigned plane_mask;
 	int ret = 0;
-	unsigned int i, j, num_fences = 0;
+	unsigned int i, j, num_fences;
 
 	/* disallow for drivers not supporting atomic: */
 	if (!drm_core_check_feature(dev, DRIVER_ATOMIC))

@@ -2137,6 +2137,8 @@ retry:
 	plane_mask = 0;
 	copied_objs = 0;
 	copied_props = 0;
+	fence_state = NULL;
+	num_fences = 0;
 
 	for (i = 0; i < arg->count_objs; i++) {
 		uint32_t obj_id, count_props;

Patches currently in stable-queue which might be from [email protected] are

queue-4.12/drm-atomic-handle-edeadlk-with-out-fences-correctly.patch queue-4.12/drm-atomic-if-the-atomic-check-fails-return-its-value-first.patch