[PATCH v3 08/13] drm/i915: GEM operations need to be done under the big lock

Tvrtko Ursulin
2016-01-08T13:04:38Z

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

VMA creation and GEM list management need the big lock.

v2:

Mutex unlock ended on the wrong path somehow. (0-day, Julia Lawall)

Not to mention drm_gem_object_unreference was there in existing
code with no mutex held.

v3:

Some callers of i915_gem_object_create_stolen_for_preallocated
already hold the lock so move the mutex into the other caller
as well.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
drivers/gpu/drm/i915/i915_gem_stolen.c | 3 +++
drivers/gpu/drm/i915/intel_display.c | 8 ++++++--
2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
index c384dc9c8a63..a97a5e762c0f 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -635,6 +635,9 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
if (!drm_mm_initialized(&dev_priv->mm.stolen))
return NULL;

+ if (WARN_ON_ONCE(!mutex_is_locked(&dev->struct_mutex)))
+ return NULL;
+
DRM_DEBUG_KMS("creating preallocated stolen object: stolen_offset=%x, gtt_offset=%x, size=%x\n",
stolen_offset, gtt_offset, size);

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index cb76054fe4c8..c502b7387509 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2534,12 +2534,16 @@ intel_alloc_initial_plane_obj(struct intel_crtc *crtc,
if (size_aligned * 2 > dev_priv->gtt.stolen_usable_size)
return false;

+ mutex_lock(&dev->struct_mutex);
+
obj = i915_gem_object_create_stolen_for_preallocated(dev,
base_aligned,
base_aligned,
size_aligned);
- if (!obj)
+ if (!obj) {
+ mutex_unlock(&dev->struct_mutex);
return false;
+ }

obj->tiling_mode = plane_config->tiling;
if (obj->tiling_mode == I915_TILING_X)
@@ -2552,12 +2556,12 @@ intel_alloc_initial_plane_obj(struct intel_crtc *crtc,
mode_cmd.modifier[0] = fb->modifier[0];
mode_cmd.flags = DRM_MODE_FB_MODIFIERS;

- mutex_lock(&dev->struct_mutex);
if (intel_framebuffer_init(dev, to_intel_framebuffer(fb),
&mode_cmd, obj)) {
DRM_DEBUG_KMS("intel fb init failed\n");
goto out_unref_obj;
}
+
mutex_unlock(&dev->struct_mutex);

DRM_DEBUG_KMS("initial plane fb obj %p\n", obj);
--
1.9.1