Return EBUSY when attempting to addmap a DRM_SHM area with a lock in it if

    dev->lock.hw_lock is already set. This fixes the case of two X Servers
    running on the same head on different VTs with interface 1.1, by making
    the 2nd head fail to inizialize like before.

1 files changed, 6 insertions, 0 deletions

diff --git a/linux/drm_bufs.h b/linux/drm_bufs.h
index 77573709f..e30e6de83 100644
--- a/linux/drm_bufs.h
+++ b/linux/drm_bufs.h
@@ -161,6 +161,12 @@ int DRM(addmap)( struct inode *inode, struct file *filp,
 		}
 		map->offset = (unsigned long)map->handle;
 		if ( map->flags & _DRM_CONTAINS_LOCK ) {
+			/* Prevent a 2nd X Server from creating a 2nd lock */
+			if (dev->lock.hw_lock != NULL) {
+				vfree( map->handle );
+				DRM(free)( map, sizeof(*map), DRM_MEM_MAPS );
+				return -EBUSY;
+			}
 			dev->sigdata.lock =
 			dev->lock.hw_lock = map->handle; /* Pointer to lock */
 		}