drm/qxl: Acquire reservation lock in GEM pin/unpin callbacks

Acquire the reservation lock directly in GEM pin callback. Same for
unpin. Prepares for further changes.

Dma-buf locking semantics require callers to hold the buffer's
reservation lock when invoking the pin and unpin callbacks. Prepare
qxl accordingly by pushing locking out of the implementation. A
follow-up patch will fix locking for all GEM code at once.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> # virtio-gpu
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Zack Rusin <zack.rusin@broadcom.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240227113853.8464-9-tzimmermann@suse.de

drivers/gpu/drm/qxl/qxl_prime.c

@@ -31,15 +31,27 @@
 int qxl_gem_prime_pin(struct drm_gem_object *obj)
 {
 	struct qxl_bo *bo = gem_to_qxl_bo(obj);
+	int r;
 
-	return qxl_bo_pin(bo);
+	r = qxl_bo_reserve(bo);
+	if (r)
+		return r;
+	r = qxl_bo_pin_locked(bo);
+	qxl_bo_unreserve(bo);
+
+	return r;
 }
 
 void qxl_gem_prime_unpin(struct drm_gem_object *obj)
 {
 	struct qxl_bo *bo = gem_to_qxl_bo(obj);
+	int r;
 
-	qxl_bo_unpin(bo);
+	r = qxl_bo_reserve(bo);
+	if (r)
+		return;
+	qxl_bo_unpin_locked(bo);
+	qxl_bo_unreserve(bo);
 }
 
 struct sg_table *qxl_gem_prime_get_sg_table(struct drm_gem_object *obj)