From patchwork Thu Feb 26 13:20:13 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tomi Valkeinen X-Patchwork-Id: 5897231 Return-Path: X-Original-To: patchwork-dri-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 20C819F536 for ; Fri, 27 Feb 2015 01:14:28 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 5613E20218 for ; Fri, 27 Feb 2015 01:14:27 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id 865DB20212 for ; Fri, 27 Feb 2015 01:14:26 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 334256E896; Thu, 26 Feb 2015 17:13:51 -0800 (PST) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org X-Greylist: delayed 671 seconds by postgrey-1.34 at gabe; Thu, 26 Feb 2015 05:32:17 PST Received: from comal.ext.ti.com (comal.ext.ti.com [198.47.26.152]) by gabe.freedesktop.org (Postfix) with ESMTP id 17BA66E233 for ; Thu, 26 Feb 2015 05:32:16 -0800 (PST) Received: from dlelxv90.itg.ti.com ([172.17.2.17]) by comal.ext.ti.com (8.13.7/8.13.7) with ESMTP id t1QDL3cc032071; Thu, 26 Feb 2015 07:21:03 -0600 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 t1QDL2k6019483; Thu, 26 Feb 2015 07:21:02 -0600 Received: from dlep33.itg.ti.com (157.170.170.75) by DLEE71.ent.ti.com (157.170.170.114) with Microsoft SMTP Server id 14.3.224.2; Thu, 26 Feb 2015 07:21:02 -0600 Received: from deskari.ti.com (ileax41-snat.itg.ti.com [10.172.224.153]) by dlep33.itg.ti.com (8.14.3/8.13.8) with ESMTP id t1QDKqkj005764; Thu, 26 Feb 2015 07:21:01 -0600 From: Tomi Valkeinen To: Laurent Pinchart , Subject: [PATCH 05/21] drm/omap: add a comment why locking is missing Date: Thu, 26 Feb 2015 15:20:13 +0200 Message-ID: <1424956829-22892-6-git-send-email-tomi.valkeinen@ti.com> X-Mailer: git-send-email 2.3.0 In-Reply-To: <1424956829-22892-1-git-send-email-tomi.valkeinen@ti.com> References: <1424956829-22892-1-git-send-email-tomi.valkeinen@ti.com> MIME-Version: 1.0 X-Mailman-Approved-At: Thu, 26 Feb 2015 17:13:46 -0800 Cc: Tomi Valkeinen , linux-omap@vger.kernel.org X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.18 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=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_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 ee8e2b3a117e..1f4f2b866379 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);