From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tomi Valkeinen Subject: [PATCH 6/9] drm/omap: add a comment why locking is missing Date: Wed, 24 Sep 2014 16:11:47 +0300 Message-ID: <1411564310-732-7-git-send-email-tomi.valkeinen@ti.com> References: <1411564310-732-1-git-send-email-tomi.valkeinen@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from comal.ext.ti.com (comal.ext.ti.com [198.47.26.152]) by gabe.freedesktop.org (Postfix) with ESMTP id C645D6E5A2 for ; Wed, 24 Sep 2014 06:12:54 -0700 (PDT) In-Reply-To: <1411564310-732-1-git-send-email-tomi.valkeinen@ti.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Rob Clark , dri-devel@lists.freedesktop.org Cc: Tomi Valkeinen List-Id: dri-devel@lists.freedesktop.org unpin_worker() calls omap_framebuffer_unpin() without any locks, which looks very suspicious. However, both pin and unpin are always called via the driver's private workqueue, so the access is synchronized that way. Add a comment to make this clear. Signed-off-by: Tomi Valkeinen --- drivers/gpu/drm/omapdrm/omap_plane.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/gpu/drm/omapdrm/omap_plane.c b/drivers/gpu/drm/omapdrm/omap_plane.c index 891a4dc608af..743d04981d71 100644 --- a/drivers/gpu/drm/omapdrm/omap_plane.c +++ b/drivers/gpu/drm/omapdrm/omap_plane.c @@ -71,6 +71,10 @@ static void unpin_worker(struct drm_flip_work *work, void *val) container_of(work, struct omap_plane, unpin_work); struct drm_device *dev = omap_plane->base.dev; + /* + * omap_framebuffer_pin/unpin are always called from priv->wq, + * so there's no need for locking here. + */ omap_framebuffer_unpin(val); mutex_lock(&dev->mode_config.mutex); drm_framebuffer_unreference(val); -- 1.9.1