From patchwork Thu Feb 14 14:03:26 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Herbert Xu X-Patchwork-Id: 10812795 X-Patchwork-Delegate: johannes@sipsolutions.net 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 BB1CE13A4 for ; Thu, 14 Feb 2019 14:03:53 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A9B2E2D50B for ; Thu, 14 Feb 2019 14:03:53 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9DDA62D516; Thu, 14 Feb 2019 14:03:53 +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=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 384F82D50B for ; Thu, 14 Feb 2019 14:03:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732498AbfBNODg (ORCPT ); Thu, 14 Feb 2019 09:03:36 -0500 Received: from orcrist.hmeau.com ([104.223.48.154]:39750 "EHLO deadmen.hmeau.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729458AbfBNODf (ORCPT ); Thu, 14 Feb 2019 09:03:35 -0500 Received: from gondobar.mordor.me.apana.org.au ([192.168.128.4] helo=gondobar) by deadmen.hmeau.com with esmtps (Exim 4.89 #2 (Debian)) id 1guHbq-00037G-Rb; Thu, 14 Feb 2019 22:03:26 +0800 Received: from herbert by gondobar with local (Exim 4.89) (envelope-from ) id 1guHbq-0000OB-JQ; Thu, 14 Feb 2019 22:03:26 +0800 Subject: [PATCH 3/4] mac80211: Use rhashtable_lookup_get_insert_fast instead of racy code References: <20190214140236.omt74prxhkfaasue@gondor.apana.org.au> To: David Miller , johannes@sipsolutions.net, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, j@w1.fi, tgraf@suug.ch, johannes.berg@intel.com, Julia Lawall Message-Id: From: Herbert Xu Date: Thu, 14 Feb 2019 22:03:26 +0800 Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The code in mesh_path_add tries to handle the case where a duplicate entry is added to the rhashtable by doing a lookup after a failed insertion. It also tries to handle races by repeating the insertion should the lookup fail. This is now unnecessary as we have rhashtable API functions that can directly return the mathcing object. Signed-off-by: Herbert Xu --- net/mac80211/mesh_pathtbl.c | 24 ++++++++---------------- 1 file changed, 8 insertions(+), 16 deletions(-) diff --git a/net/mac80211/mesh_pathtbl.c b/net/mac80211/mesh_pathtbl.c index c3a7396fb955..8902395e406e 100644 --- a/net/mac80211/mesh_pathtbl.c +++ b/net/mac80211/mesh_pathtbl.c @@ -404,7 +404,6 @@ struct mesh_path *mesh_path_add(struct ieee80211_sub_if_data *sdata, { struct mesh_table *tbl; struct mesh_path *mpath, *new_mpath; - int ret; if (ether_addr_equal(dst, sdata->vif.addr)) /* never add ourselves as neighbours */ @@ -422,25 +421,18 @@ struct mesh_path *mesh_path_add(struct ieee80211_sub_if_data *sdata, tbl = sdata->u.mesh.mesh_paths; spin_lock_bh(&tbl->walk_lock); - do { - ret = rhashtable_lookup_insert_fast(&tbl->rhead, - &new_mpath->rhash, - mesh_rht_params); - - if (ret == -EEXIST) - mpath = rhashtable_lookup_fast(&tbl->rhead, - dst, - mesh_rht_params); - else if (!ret) - hlist_add_head(&new_mpath->walk_list, &tbl->walk_head); - } while (unlikely(ret == -EEXIST && !mpath)); + mpath = rhashtable_lookup_get_insert_fast(&tbl->rhead, + &new_mpath->rhash, + mesh_rht_params); + if (!mpath) + hlist_add_head(&new_mpath->walk_list, &tbl->walk_head); spin_unlock_bh(&tbl->walk_lock); - if (ret) { + if (mpath) { kfree(new_mpath); - if (ret != -EEXIST) - return ERR_PTR(ret); + if (IS_ERR(mpath)) + return mpath; new_mpath = mpath; }