[PATCH 3.19 148/177] drm/i915: Check obj->vma_list under the struct_mutex

Greg Kroah-Hartman
2015-03-16T14:18:00Z

From: Chris Wilson <chris@chris-wilson.co.uk>

commit 6c31a614c43ae274546f736b2a33363e149c3dc2 upstream.

When we walk the list of vma, or even for protecting against concurrent
framebuffer creation, we must hold the struct_mutex or else a second
thread can corrupt the list as we walk it.

Fixes regression from
commit d7f46fc4e7323887494db13f063a8e59861fefb0
Author: Ben Widawsky <benjamin.widawsky@intel.com>
Date: Fri Dec 6 14:10:55 2013 -0800

drm/i915: Make pin count per VMA

References: https://bugs.freedesktop.org/show_bug.cgi?id=89085
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/i915/i915_gem_tiling.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/i915/i915_gem_tiling.c
+++ b/drivers/gpu/drm/i915/i915_gem_tiling.c
@@ -335,9 +335,10 @@ i915_gem_set_tiling(struct drm_device *d
return -EINVAL;
}

+ mutex_lock(&dev->struct_mutex);
if (i915_gem_obj_is_pinned(obj) || obj->framebuffer_references) {
- drm_gem_object_unreference_unlocked(&obj->base);
- return -EBUSY;
+ ret = -EBUSY;
+ goto err;
}

if (args->tiling_mode == I915_TILING_NONE) {
@@ -369,7 +370,6 @@ i915_gem_set_tiling(struct drm_device *d
}
}

- mutex_lock(&dev->struct_mutex);
if (args->tiling_mode != obj->tiling_mode ||
args->stride != obj->stride) {
/* We need to rebind the object if its current allocation
@@ -424,6 +424,7 @@ i915_gem_set_tiling(struct drm_device *d
obj->bit_17 = NULL;
}

+err:
drm_gem_object_unreference(&obj->base);
mutex_unlock(&dev->struct_mutex);