drm/aperture: Fix missing unlock on error in devm_aperture_acquire()

Add the missing unlock before return from function devm_aperture_acquire()
in the error handling case.
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: 730e7992 ("drm/aperture: Add infrastructure for aperture ownership")
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Maxime Ripard <maxime@cerno.tech>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Link: https://patchwork.freedesktop.org/patch/msgid/1620895564-52367-1-git-send-email-zou_wei@huawei.com

drivers/gpu/drm/drm_aperture.c

@@ -164,13 +164,17 @@ static int devm_aperture_acquire(struct drm_device *dev,
 
 	list_for_each(pos, &drm_apertures) {
 		ap = container_of(pos, struct drm_aperture, lh);
-		if (overlap(base, end, ap->base, ap->base + ap->size))
+		if (overlap(base, end, ap->base, ap->base + ap->size)) {
+			mutex_unlock(&drm_apertures_lock);
 			return -EBUSY;
 		}
+	}
 
 	ap = devm_kzalloc(dev->dev, sizeof(*ap), GFP_KERNEL);
-	if (!ap)
+	if (!ap) {
+		mutex_unlock(&drm_apertures_lock);
 		return -ENOMEM;
+	}
 
 	ap->dev = dev;
 	ap->base = base;