drm/i915; Only increment the user-pin-count after successfully pinning the bo

commit 93be8788e648817d62fda33e2998eb6ca6ebf3a3 upstream.

As along the error path we do not correct the user pin-count for the
failure, we may end up with userspace believing that it has a pinned
object at offset 0 (when interrupted by a signal for example).

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Weng Meiling <wengmeiling.weng@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index eb33945..a0fa218 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3411,14 +3411,15 @@ i915_gem_pin_ioctl(struct drm_device *dev, void *data,
                goto out;
        }
 
-       obj->user_pin_count++;
-       obj->pin_filp = file;
-       if (obj->user_pin_count == 1) {
+       if (obj->user_pin_count == 0) {
                ret = i915_gem_object_pin(obj, args->alignment, true);
                if (ret)
                        goto out;
        }
 
+       obj->user_pin_count++;
+       obj->pin_filp = file;
+
        /* XXX - flush the CPU caches for pinned objects
         * as the X server doesn't manage domains yet
         */