From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2754C00140 for ; Thu, 18 Aug 2022 10:47:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244154AbiHRKro (ORCPT ); Thu, 18 Aug 2022 06:47:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40760 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244141AbiHRKrj (ORCPT ); Thu, 18 Aug 2022 06:47:39 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D61D9816BD; Thu, 18 Aug 2022 03:47:35 -0700 (PDT) Received: from dggpemm500021.china.huawei.com (unknown [172.30.72.55]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4M7hPf5yGpzGpVw; Thu, 18 Aug 2022 18:45:58 +0800 (CST) Received: from dggpemm500007.china.huawei.com (7.185.36.183) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 18 Aug 2022 18:47:32 +0800 Received: from [10.174.178.174] (10.174.178.174) by dggpemm500007.china.huawei.com (7.185.36.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 18 Aug 2022 18:47:31 +0800 Subject: Re: [PATCH -next] net: neigh: use dev_kfree_skb_irq instead of kfree_skb() To: "Denis V. Lunev" , , CC: , , References: <20220818043729.412753-1-yangyingliang@huawei.com> <79784952-0d15-8a4a-aa8d-590bc243ab5e@virtuozzo.com> From: Yang Yingliang Message-ID: <705de4aa-91bf-c559-419c-2bfd083c9067@huawei.com> Date: Thu, 18 Aug 2022 18:47:31 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <79784952-0d15-8a4a-aa8d-590bc243ab5e@virtuozzo.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.174.178.174] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpemm500007.china.huawei.com (7.185.36.183) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 2022/8/18 17:00, Denis V. Lunev wrote: > On 18.08.2022 06:37, 'Yang Yingliang' via den wrote: >> It is not allowed to call kfree_skb() from hardware interrupt >> context or with interrupts being disabled. So replace kfree_skb() >> with dev_kfree_skb_irq() under spin_lock_irqsave(). >> >> Fixes: 66ba215cb513 ("neigh: fix possible DoS due to net iface >> start/stop loop") >> Signed-off-by: Yang Yingliang >> --- >>   net/core/neighbour.c | 2 +- >>   1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/net/core/neighbour.c b/net/core/neighbour.c >> index 5b669eb80270..167826200f3e 100644 >> --- a/net/core/neighbour.c >> +++ b/net/core/neighbour.c >> @@ -328,7 +328,7 @@ static void pneigh_queue_purge(struct >> sk_buff_head *list, struct net *net) >>               __skb_unlink(skb, list); >>                 dev_put(dev); >> -            kfree_skb(skb); >> +            dev_kfree_skb_irq(skb); >>           } >>           skb = skb_next; >>       } > > Technically this is pretty much correct, but would it be better to > move all skb to purge into the new list and after that purge > them at once? > > what about something like this? > > diff --git a/net/core/neighbour.c b/net/core/neighbour.c > index aa16a8017c5e..f7e30daa46ae 100644 > --- a/net/core/neighbour.c > +++ b/net/core/neighbour.c > @@ -311,6 +311,9 @@ static void pneigh_queue_purge(struct sk_buff_head > *list, struct net *net) >  { >         unsigned long flags; >         struct sk_buff *skb; > +       struct sk_buff_head tmp; > + > +       skb_queue_head_init(&tmp); > >         spin_lock_irqsave(&list->lock, flags); >         skb = skb_peek(list); > @@ -318,12 +321,16 @@ static void pneigh_queue_purge(struct > sk_buff_head *list, struct net *net) >                 struct sk_buff *skb_next = skb_peek_next(skb, list); >                 if (net == NULL || net == dev_net(skb->dev)) { >                         __skb_unlink(skb, list); > -                       dev_put(skb->dev); > -                       kfree_skb(skb); > +                       __skb_queue_tail(&tmp, skb); >                 } >                 skb = skb_next; >         } while (skb != NULL); >         spin_unlock_irqrestore(&list->lock, flags); > + > +       while ((skb = __skb_dequeue(&tmp)) != NULL) { > +               dev_put(skb->dev); > +               kfree_skb(skb); > +       } >  } It's better, I can send a v2 later. Thanks, Yang > > iris ~/src/linux-2.6 $ > > .