From patchwork Wed Sep 3 11:55:10 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tomi Valkeinen X-Patchwork-Id: 4834831 Return-Path: X-Original-To: patchwork-dri-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 5B7E3C0338 for ; Wed, 3 Sep 2014 13:43:30 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 73C7920221 for ; Wed, 3 Sep 2014 13:43:28 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id D57E82020F for ; Wed, 3 Sep 2014 13:43:26 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0B0D86E594; Wed, 3 Sep 2014 06:43:13 -0700 (PDT) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from comal.ext.ti.com (comal.ext.ti.com [198.47.26.152]) by gabe.freedesktop.org (Postfix) with ESMTP id 1658E6E547 for ; Wed, 3 Sep 2014 04:55:41 -0700 (PDT) Received: from dlelxv90.itg.ti.com ([172.17.2.17]) by comal.ext.ti.com (8.13.7/8.13.7) with ESMTP id s83BtexJ032701; Wed, 3 Sep 2014 06:55:40 -0500 Received: from DLEE71.ent.ti.com (dlee71.ent.ti.com [157.170.170.114]) by dlelxv90.itg.ti.com (8.14.3/8.13.8) with ESMTP id s83BtdKE017676; Wed, 3 Sep 2014 06:55:40 -0500 Received: from dflp33.itg.ti.com (10.64.6.16) by DLEE71.ent.ti.com (157.170.170.114) with Microsoft SMTP Server id 14.3.174.1; Wed, 3 Sep 2014 06:55:39 -0500 Received: from deskari.lan (ileax41-snat.itg.ti.com [10.172.224.153]) by dflp33.itg.ti.com (8.14.3/8.13.8) with ESMTP id s83BtNQJ004347; Wed, 3 Sep 2014 06:55:38 -0500 From: Tomi Valkeinen To: Rob Clark , Subject: [PATCH 9/9] drm/omap: add a comment why locking is missing Date: Wed, 3 Sep 2014 14:55:10 +0300 Message-ID: <1409745310-19092-9-git-send-email-tomi.valkeinen@ti.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1409745310-19092-1-git-send-email-tomi.valkeinen@ti.com> References: <1409745310-19092-1-git-send-email-tomi.valkeinen@ti.com> MIME-Version: 1.0 X-Mailman-Approved-At: Wed, 03 Sep 2014 06:43:10 -0700 Cc: Tomi Valkeinen X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Spam-Status: No, score=-5.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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);