patches/drm-ttm-fixed-a-read-write-lock-imbalance.patch

From 025af189fb44250206dd8a32fa4a682392af3301 Mon Sep 17 00:00:00 2001
From: Thomas Hellstrom <thellstrom@vmware.com>
Date: Fri, 20 Nov 2015 11:43:50 -0800
Subject: drm/ttm: Fixed a read/write lock imbalance

commit 025af189fb44250206dd8a32fa4a682392af3301 upstream.

In ttm_write_lock(), the uninterruptible path should call
__ttm_write_lock() not __ttm_read_lock().  This fixes a vmwgfx hang
on F23 start up.

syeh: Extracted this from one of Thomas' internal patches.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
 drivers/gpu/drm/ttm/ttm_lock.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/ttm/ttm_lock.c
+++ b/drivers/gpu/drm/ttm/ttm_lock.c
@@ -180,7 +180,7 @@ int ttm_write_lock(struct ttm_lock *lock
 			spin_unlock(&lock->lock);
 		}
 	} else
-		wait_event(lock->queue, __ttm_read_lock(lock));
+		wait_event(lock->queue, __ttm_write_lock(lock));
 
 	return ret;
 }