From patchwork Thu Aug 20 06:48:39 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xin Long X-Patchwork-Id: 1348209 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=HJn1uRjp; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BXFc25t96z9sR4 for ; Thu, 20 Aug 2020 16:48:50 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726781AbgHTGst (ORCPT ); Thu, 20 Aug 2020 02:48:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60364 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725780AbgHTGss (ORCPT ); Thu, 20 Aug 2020 02:48:48 -0400 Received: from mail-pj1-x1042.google.com (mail-pj1-x1042.google.com [IPv6:2607:f8b0:4864:20::1042]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8CA41C061757; Wed, 19 Aug 2020 23:48:48 -0700 (PDT) Received: by mail-pj1-x1042.google.com with SMTP id e4so559323pjd.0; Wed, 19 Aug 2020 23:48:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=jm+uUDSmmx9X1srdhmuJqsAe+TT5/kJh3UlKWgVNgVw=; b=HJn1uRjpGV0DhRy/Wceim0P9RIA4TesPYKX6RA6GTr6TtUBSWMRf4zuFwWLwn4anFf g9AD4wbX4fYOXAb3y2KF6oB7gugTUi+UlY7zopLQXY1dz/aFPMNfyK/E6Zwf+MFCS58w YHbXDecPPVi2AaBxe7aXEqvtxJVOpmp2VBuzclRYOG0NWrFIughBcKTyxfoL/G4NdYqX H7WFKCisPljyaBVYQWZIpvlCSl0W5P6xSQuonxwmk2TZruEcvmLDTR6rGLiPFDk4CU5p m7EffC8PtZoo7JCpm8Cju9Tu3j90FYuXziBsjJ0CVGshCcGQLpyPN4sPsyW/uM5lWfmP e2YQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=jm+uUDSmmx9X1srdhmuJqsAe+TT5/kJh3UlKWgVNgVw=; b=RM3E3IwqgftloBqIkgQ6VGzQF71enYXkeQH1k9Cm2DfpX063ibtc3A5STCK3kJv04t uMQPXPhL9UVQiuh5pwB7YcQENr1pEVlDH8JwdlE74LNFWuWniS8fcbgk2Bm6j8Oeb8i5 hfFsoMTkfPiRtbAMVm12sNmmNb1GUhJA3Xnw9Ew00x5Ims93zTk7cX6IzwfooTyhEOcY JnWFVcLpeBCFwYMUgUjVPpEoCmiHrd66k0UMxNqNkiBGRBYBBFFoV81Dx7nFqnGbevdS ZaIvUjaII/LVObW3re8DsrJ0g09eQ9NpxxMpc5BQ3/3YdCCJbMPq2QOsdAB0Pv4dlqdG Y1Ew== X-Gm-Message-State: AOAM530bHFfEKmpLXhqbENMGbOzOjOVga8ATbebIUH6W5fSANT36TjO0 U9VwRBdaKlEQg5EpRONdne7CwA+Oatdtkg== X-Google-Smtp-Source: ABdhPJzyUsvupUEj90FwoqrcE1uxgomLzTTgJXrbMSN+Xm5wJgBh/5q7BepmiBAbbTKf5E/Sana1/Q== X-Received: by 2002:a17:90b:4b89:: with SMTP id lr9mr437065pjb.190.1597906127508; Wed, 19 Aug 2020 23:48:47 -0700 (PDT) Received: from localhost ([209.132.188.80]) by smtp.gmail.com with ESMTPSA id w7sm1454778pfi.164.2020.08.19.23.48.46 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 19 Aug 2020 23:48:46 -0700 (PDT) From: Xin Long To: network dev , linux-sctp@vger.kernel.org Cc: davem@davemloft.net, Eric Dumazet , Marcelo Ricardo Leitner , Neil Horman Subject: [PATCH net] sctp: not disable bh in the whole sctp_get_port_local() Date: Thu, 20 Aug 2020 14:48:39 +0800 Message-Id: X-Mailer: git-send-email 2.1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org With disabling bh in the whole sctp_get_port_local(), when snum == 0 and too many ports have been used, the do-while loop will take the cpu for a long time and cause cpu stuck: [ ] watchdog: BUG: soft lockup - CPU#11 stuck for 22s! [ ] RIP: 0010:native_queued_spin_lock_slowpath+0x4de/0x940 [ ] Call Trace: [ ] _raw_spin_lock+0xc1/0xd0 [ ] sctp_get_port_local+0x527/0x650 [sctp] [ ] sctp_do_bind+0x208/0x5e0 [sctp] [ ] sctp_autobind+0x165/0x1e0 [sctp] [ ] sctp_connect_new_asoc+0x355/0x480 [sctp] [ ] __sctp_connect+0x360/0xb10 [sctp] There's no need to disable bh in the whole function of sctp_get_port_local. So fix this cpu stuck by removing local_bh_disable() called at the beginning, and using spin_lock_bh() instead. The same thing was actually done for inet_csk_get_port() in Commit ea8add2b1903 ("tcp/dccp: better use of ephemeral ports in bind()"). Thanks to Marcelo for pointing the buggy code out. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Ying Xu Signed-off-by: Xin Long --- net/sctp/socket.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index ec1fba1..f0f9956 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -8060,8 +8060,6 @@ static int sctp_get_port_local(struct sock *sk, union sctp_addr *addr) pr_debug("%s: begins, snum:%d\n", __func__, snum); - local_bh_disable(); - if (snum == 0) { /* Search for an available port. */ int low, high, remaining, index; @@ -8079,20 +8077,20 @@ static int sctp_get_port_local(struct sock *sk, union sctp_addr *addr) continue; index = sctp_phashfn(net, rover); head = &sctp_port_hashtable[index]; - spin_lock(&head->lock); + spin_lock_bh(&head->lock); sctp_for_each_hentry(pp, &head->chain) if ((pp->port == rover) && net_eq(net, pp->net)) goto next; break; next: - spin_unlock(&head->lock); + spin_unlock_bh(&head->lock); } while (--remaining > 0); /* Exhausted local port range during search? */ ret = 1; if (remaining <= 0) - goto fail; + return ret; /* OK, here is the one we will use. HEAD (the port * hash table list entry) is non-NULL and we hold it's @@ -8107,7 +8105,7 @@ static int sctp_get_port_local(struct sock *sk, union sctp_addr *addr) * port iterator, pp being NULL. */ head = &sctp_port_hashtable[sctp_phashfn(net, snum)]; - spin_lock(&head->lock); + spin_lock_bh(&head->lock); sctp_for_each_hentry(pp, &head->chain) { if ((pp->port == snum) && net_eq(pp->net, net)) goto pp_found; @@ -8207,10 +8205,7 @@ static int sctp_get_port_local(struct sock *sk, union sctp_addr *addr) ret = 0; fail_unlock: - spin_unlock(&head->lock); - -fail: - local_bh_enable(); + spin_unlock_bh(&head->lock); return ret; }