Merge remote-tracking branch 'linus/master' into staging/for_v3.8

* linus/master: (1428 commits)
  futex: avoid wake_futex() for a PI futex_q
  watchdog: using u64 in get_sample_period()
  writeback: put unused inodes to LRU after writeback completion
  mm: vmscan: check for fatal signals iff the process was throttled
  Revert "mm: remove __GFP_NO_KSWAPD"
  proc: check vma->vm_file before dereferencing
  UAPI: strip the _UAPI prefix from header guards during header installation
  include/linux/bug.h: fix sparse warning related to BUILD_BUG_ON_INVALID
  Linux 3.7-rc7
  powerpc/eeh: Do not invalidate PE properly
  ALSA: hda - Fix build without CONFIG_PM
  of/address: sparc: Declare of_iomap as an extern function for sparc again
  PM / QoS: fix wrong error-checking condition
  bnx2x: remove redundant warning log
  vxlan: fix command usage in its doc
  8139cp: revert "set ring address before enabling receiver"
  MPI: Fix compilation on MIPS with GCC 4.4 and newer
  MIPS: Fix crash that occurs when function tracing is enabled
  MIPS: Merge overlapping bootmem ranges
  jbd: Fix lock ordering bug in journal_unmap_buffer()
  ...

1 files changed, 30 insertions, 14 deletions

diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index 7ef1b673e1be..133b4132983e 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -121,6 +121,8 @@ int drm_open(struct inode *inode, struct file *filp)
 	int minor_id = iminor(inode);
 	struct drm_minor *minor;
 	int retcode = 0;
+	int need_setup = 0;
+	struct address_space *old_mapping;
 
 	minor = idr_find(&drm_minors_idr, minor_id);
 	if (!minor)
@@ -132,23 +134,37 @@ int drm_open(struct inode *inode, struct file *filp)
 	if (drm_device_is_unplugged(dev))
 		return -ENODEV;
 
+	if (!dev->open_count++)
+		need_setup = 1;
+	mutex_lock(&dev->struct_mutex);
+	old_mapping = dev->dev_mapping;
+	if (old_mapping == NULL)
+		dev->dev_mapping = &inode->i_data;
+	/* ihold ensures nobody can remove inode with our i_data */
+	ihold(container_of(dev->dev_mapping, struct inode, i_data));
+	inode->i_mapping = dev->dev_mapping;
+	filp->f_mapping = dev->dev_mapping;
+	mutex_unlock(&dev->struct_mutex);
+
 	retcode = drm_open_helper(inode, filp, dev);
-	if (!retcode) {
-		atomic_inc(&dev->counts[_DRM_STAT_OPENS]);
-		if (!dev->open_count++)
-			retcode = drm_setup(dev);
-	}
-	if (!retcode) {
-		mutex_lock(&dev->struct_mutex);
-		if (dev->dev_mapping == NULL)
-			dev->dev_mapping = &inode->i_data;
-		/* ihold ensures nobody can remove inode with our i_data */
-		ihold(container_of(dev->dev_mapping, struct inode, i_data));
-		inode->i_mapping = dev->dev_mapping;
-		filp->f_mapping = dev->dev_mapping;
-		mutex_unlock(&dev->struct_mutex);
+	if (retcode)
+		goto err_undo;
+	atomic_inc(&dev->counts[_DRM_STAT_OPENS]);
+	if (need_setup) {
+		retcode = drm_setup(dev);
+		if (retcode)
+			goto err_undo;
 	}
+	return 0;
 
+err_undo:
+	mutex_lock(&dev->struct_mutex);
+	filp->f_mapping = old_mapping;
+	inode->i_mapping = old_mapping;
+	iput(container_of(dev->dev_mapping, struct inode, i_data));
+	dev->dev_mapping = old_mapping;
+	mutex_unlock(&dev->struct_mutex);
+	dev->open_count--;
 	return retcode;
 }
 EXPORT_SYMBOL(drm_open);