Merge branch 'stable/for-jens-3.9' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen into for-3.9/drivers

Konrad writes:

Please git pull the following branch:

 git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git stable/for-jens-3.9

which has bug-fixes that did not make it in v3.8. They all are marked as
material for the stable tree as well. There are two bug-fixes for
the code that has been in there for some time (that is the Jan's fix
and one of mine). And there are two bug-fixes for the persistent grant
feature that debuted in v3.8 for xen blk[back|front]end.

1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index d6a994a0739..26d08bb5821 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -539,6 +539,8 @@ i915_gem_execbuffer_relocate_slow(struct drm_device *dev,
 	total = 0;
 	for (i = 0; i < count; i++) {
 		struct drm_i915_gem_relocation_entry __user *user_relocs;
+		u64 invalid_offset = (u64)-1;
+		int j;
 
 		user_relocs = (void __user *)(uintptr_t)exec[i].relocs_ptr;
 
@@ -549,6 +551,25 @@ i915_gem_execbuffer_relocate_slow(struct drm_device *dev,
 			goto err;
 		}
 
+		/* As we do not update the known relocation offsets after
+		 * relocating (due to the complexities in lock handling),
+		 * we need to mark them as invalid now so that we force the
+		 * relocation processing next time. Just in case the target
+		 * object is evicted and then rebound into its old
+		 * presumed_offset before the next execbuffer - if that
+		 * happened we would make the mistake of assuming that the
+		 * relocations were valid.
+		 */
+		for (j = 0; j < exec[i].relocation_count; j++) {
+			if (copy_to_user(&user_relocs[j].presumed_offset,
+					 &invalid_offset,
+					 sizeof(invalid_offset))) {
+				ret = -EFAULT;
+				mutex_lock(&dev->struct_mutex);
+				goto err;
+			}
+		}
+
 		reloc_offset[i] = total;
 		total += exec[i].relocation_count;
 	}