From patchwork Wed Sep 24 13:11:47 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tomi Valkeinen X-Patchwork-Id: 4967441 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 4FAFEBEEA5 for ; Wed, 24 Sep 2014 15:23:15 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 183522021A for ; Wed, 24 Sep 2014 15:23:14 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id CB275201B9 for ; Wed, 24 Sep 2014 15:23:12 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 03F706E60F; Wed, 24 Sep 2014 08:23:04 -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 C645D6E5A2 for ; Wed, 24 Sep 2014 06:12:54 -0700 (PDT) Received: from dflxv15.itg.ti.com ([128.247.5.124]) by comal.ext.ti.com (8.13.7/8.13.7) with ESMTP id s8ODCr9K027572; Wed, 24 Sep 2014 08:12:53 -0500 Received: from DLEE70.ent.ti.com (dlemailx.itg.ti.com [157.170.170.113]) by dflxv15.itg.ti.com (8.14.3/8.13.8) with ESMTP id s8ODCrug007131; Wed, 24 Sep 2014 08:12:53 -0500 Received: from dlep33.itg.ti.com (157.170.170.75) by DLEE70.ent.ti.com (157.170.170.113) with Microsoft SMTP Server id 14.3.174.1; Wed, 24 Sep 2014 08:12:53 -0500 Received: from deskari.lan (ileax41-snat.itg.ti.com [10.172.224.153]) by dlep33.itg.ti.com (8.14.3/8.13.8) with ESMTP id s8ODCeGf003773; Wed, 24 Sep 2014 08:12:52 -0500 From: Tomi Valkeinen To: Rob Clark , 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> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1411564310-732-1-git-send-email-tomi.valkeinen@ti.com> References: <1411564310-732-1-git-send-email-tomi.valkeinen@ti.com> MIME-Version: 1.0 X-Mailman-Approved-At: Wed, 24 Sep 2014 08:22:55 -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=-4.9 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);