From c6be27401fbc12ec72bac13d07e3cc93bd63732a Mon Sep 17 00:00:00 2001
From: Thomas Hellstrom <thomas-at-tungstengraphics-dot-com>
Date: Mon, 2 Oct 2006 13:34:30 +0200
Subject: [PATCH] Trap and be verbose about a deadlock that occurs with AIGLX
 and drivers that use drm_reclaim_buffers_locked().

---
 linux-core/drm_fops.c | 16 ++++++++++++++--
 linux-core/drm_lock.c |  8 +++++++-
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/linux-core/drm_fops.c b/linux-core/drm_fops.c
index dcc05a0a..e4385cf6 100644
--- a/linux-core/drm_fops.c
+++ b/linux-core/drm_fops.c
@@ -421,14 +421,26 @@ int drm_release(struct inode *inode, struct file *filp)
 		  dev->open_count);
 
 	if (dev->driver->reclaim_buffers_locked) {
-		retcode = drm_kernel_take_hw_lock(filp);
+	        unsigned long _end = jiffies + DRM_HZ*3;
+
+		do {
+			retcode = drm_kernel_take_hw_lock(filp);
+		} while(retcode && !time_after_eq(jiffies,_end));
+
 		if (!retcode) {
 			dev->driver->reclaim_buffers_locked(dev, filp);
 
 			drm_lock_free(dev, &dev->lock.hw_lock->lock,
 				      _DRM_LOCKING_CONTEXT(dev->lock.hw_lock->lock));
+		} else {
+			DRM_ERROR("Reclaim buffers locked deadlock.\n");
+			DRM_ERROR("This is probably a single thread having multiple\n");
+			DRM_ERROR("DRM file descriptors open either dying or "
+				  "closing file descriptors\n");
+			DRM_ERROR("while having the lock. I will not reclaim buffers.\n");
+			DRM_ERROR("Locking context is 0x%08x\n",
+				  _DRM_LOCKING_CONTEXT(dev->lock.hw_lock->lock));
 		}
-
 	} else if (drm_i_have_hw_lock(filp)) {
 		DRM_DEBUG("File %p released, freeing lock for context %d\n",
 			  filp, _DRM_LOCKING_CONTEXT(dev->lock.hw_lock->lock));
diff --git a/linux-core/drm_lock.c b/linux-core/drm_lock.c
index 04c145a6..0cf183a7 100644
--- a/linux-core/drm_lock.c
+++ b/linux-core/drm_lock.c
@@ -343,6 +343,7 @@ int drm_kernel_take_hw_lock(struct file *filp)
 	DRM_DEVICE;
 
 	int ret = 0; 
+	unsigned long _end = jiffies + 3*DRM_HZ;
 	
 	if (!drm_i_have_hw_lock(filp)) {
 	
@@ -364,7 +365,12 @@ int drm_kernel_take_hw_lock(struct file *filp)
 				break;	/* Got lock */
 			}
 			/* Contention */
-			schedule();
+			if (time_after_eq(jiffies,_end)) {
+			        ret = -EBUSY;
+				break;
+			}
+
+			schedule_timeout(1);
 			if (signal_pending(current)) {
 				ret = -ERESTARTSYS;
 				break;