drm/i915: Hold the spinlock whilst resetting unpin_work along error path

Delay taking the mutex until we need to and ensure that we hold the
spinlock when resetting unpin_work on the error path. Also defer the
debugging print messages until after we have released the spinlock.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Kristian Høgsberg <krh@bitplanet.net>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>

1 files changed, 12 insertions, 8 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index cfac4dd1d483..1845a068cca5 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4667,8 +4667,6 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
         if (work == NULL)
                 return -ENOMEM;
 
-        mutex_lock(&dev->struct_mutex);
-
         work->event = event;
         work->dev = crtc->dev;
         intel_fb = to_intel_framebuffer(crtc->fb);
@@ -4678,10 +4676,10 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
         /* We borrow the event spin lock for protecting unpin_work */
         spin_lock_irqsave(&dev->event_lock, flags);
         if (intel_crtc->unpin_work) {
-                DRM_DEBUG_DRIVER("flip queue: crtc already busy\n");
                 spin_unlock_irqrestore(&dev->event_lock, flags);
                 kfree(work);
-                mutex_unlock(&dev->struct_mutex);
+
+                DRM_DEBUG_DRIVER("flip queue: crtc already busy\n");
                 return -EBUSY;
         }
         intel_crtc->unpin_work = work;
@@ -4690,13 +4688,19 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
         intel_fb = to_intel_framebuffer(fb);
         obj = intel_fb->obj;
 
+        mutex_lock(&dev->struct_mutex);
         ret = intel_pin_and_fence_fb_obj(dev, obj);
         if (ret != 0) {
-                DRM_DEBUG_DRIVER("flip queue: %p pin & fence failed\n",
-                          to_intel_bo(obj));
-                kfree(work);
-                intel_crtc->unpin_work = NULL;
                 mutex_unlock(&dev->struct_mutex);
+
+                spin_lock_irqsave(&dev->event_lock, flags);
+                intel_crtc->unpin_work = NULL;
+                spin_unlock_irqrestore(&dev->event_lock, flags);
+
+                kfree(work);
+
+                DRM_DEBUG_DRIVER("flip queue: %p pin & fence failed\n",
+                                 to_intel_bo(obj));
                 return ret;
         }