From patchwork Fri Aug 2 16:36:59 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 11073867 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 880F913AC for ; Fri, 2 Aug 2019 16:37:13 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 77B0A28756 for ; Fri, 2 Aug 2019 16:37:13 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6BB3328874; Fri, 2 Aug 2019 16:37:13 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=unavailable version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 3544728756 for ; Fri, 2 Aug 2019 16:37:13 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 22A456EEE5; Fri, 2 Aug 2019 16:37:11 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6DDAD6EEE4; Fri, 2 Aug 2019 16:37:08 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from haswell.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 17822167-1500050 for multiple; Fri, 02 Aug 2019 17:37:01 +0100 From: Chris Wilson To: dri-devel@lists.freedesktop.org Subject: [PATCH 2/2] drm/syncobj: Lookup the syncobj with RCU protection Date: Fri, 2 Aug 2019 17:36:59 +0100 Message-Id: <20190802163659.23255-2-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.23.0.rc0 In-Reply-To: <20190802163659.23255-1-chris@chris-wilson.co.uk> References: <20190802163659.23255-1-chris@chris-wilson.co.uk> MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Daniel Vetter , intel-gfx@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP Relax the spinlock used for looking up the handle in the XArray and acquiring a reference to it to an RCU protected critical section. This incurs the requirement that we protect the syncobj struct itself using RCU, which we achieve by simply calling kfree_rcu() and being more careful in acquiring our reference. Signed-off-by: Chris Wilson Cc: Daniel Vetter --- drivers/gpu/drm/drm_syncobj.c | 12 +++++------- include/drm/drm_syncobj.h | 2 ++ 2 files changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c index 4fc71dc9fc43..aafc03986a48 100644 --- a/drivers/gpu/drm/drm_syncobj.c +++ b/drivers/gpu/drm/drm_syncobj.c @@ -86,13 +86,11 @@ struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private, { struct drm_syncobj *syncobj; - xa_lock(&file_private->syncobjs); - + rcu_read_lock(); syncobj = xa_load(&file_private->syncobjs, handle); - if (syncobj) - drm_syncobj_get(syncobj); - - xa_unlock(&file_private->syncobjs); + if (syncobj && !kref_get_unless_zero(&syncobj->refcount)) + syncobj = NULL; + rcu_read_unlock(); return syncobj; } @@ -309,7 +307,7 @@ void drm_syncobj_free(struct kref *kref) struct drm_syncobj, refcount); drm_syncobj_replace_fence(syncobj, NULL); - kfree(syncobj); + kfree_rcu(syncobj, rcu); } EXPORT_SYMBOL(drm_syncobj_free); diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h index 6cf7243a1dc5..7c1503d47abf 100644 --- a/include/drm/drm_syncobj.h +++ b/include/drm/drm_syncobj.h @@ -61,6 +61,8 @@ struct drm_syncobj { * @file: A file backing for this syncobj. */ struct file *file; + + struct rcu_head rcu; }; void drm_syncobj_free(struct kref *kref);