linux-kernel - [145/205] drm/i915: Hold the spinlock whilst resetting unpin

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Date:	Fri, 30 Jul 2010 10:52:42 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Chris Wilson <chris@...is-wilson.co.uk>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Kristian HÃžgsberg <krh@...planet.net>,
	Eric Anholt <eric@...olt.net>
Subject: [145/205] drm/i915: Hold the spinlock whilst resetting unpin_work along error path

2.6.34-stable review patch.  If anyone has any objections, please let us know.

------------------

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

commit 468f0b44ce4b002ca7d9260f802a341854752c02 upstream.

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@...is-wilson.co.uk>
Cc: Jesse Barnes <jbarnes@...tuousgeek.org>
Cc: Kristian Høgsberg <krh@...planet.net>
Reviewed-by: Jesse Barnes <jbarnes@...tuousgeek.org>
Signed-off-by: Eric Anholt <eric@...olt.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/gpu/drm/i915/intel_display.c |   20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4239,8 +4239,6 @@ static int intel_crtc_page_flip(struct d
 	if (work == NULL)
 		return -ENOMEM;
 
-	mutex_lock(&dev->struct_mutex);
-
 	work->event = event;
 	work->dev = crtc->dev;
 	intel_fb = to_intel_framebuffer(crtc->fb);
@@ -4250,10 +4248,10 @@ static int intel_crtc_page_flip(struct d
 	/* 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;
@@ -4262,13 +4260,19 @@ static int intel_crtc_page_flip(struct d
 	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;
 	}
 


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