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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 611EBC43441 for ; Wed, 28 Nov 2018 18:59:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 30748205C9 for ; Wed, 28 Nov 2018 18:59:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 30748205C9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=davemloft.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729193AbeK2GBp (ORCPT ); Thu, 29 Nov 2018 01:01:45 -0500 Received: from shards.monkeyblade.net ([23.128.96.9]:36392 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726595AbeK2GBp (ORCPT ); Thu, 29 Nov 2018 01:01:45 -0500 Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::bf5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id EFDAE14E0ECFF; Wed, 28 Nov 2018 10:59:06 -0800 (PST) Date: Wed, 28 Nov 2018 10:59:06 -0800 (PST) Message-Id: <20181128.105906.2127945279482643879.davem@davemloft.net> To: bianpan2016@163.com Cc: Jose.Abreu@synopsys.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] net: dwc-xlgmac: set skb to NULL after freeing it From: David Miller In-Reply-To: <1543396853-35188-1-git-send-email-bianpan2016@163.com> References: <1543396853-35188-1-git-send-email-bianpan2016@163.com> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Wed, 28 Nov 2018 10:59:07 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pan Bian Date: Wed, 28 Nov 2018 17:20:53 +0800 > @@ -1180,6 +1180,7 @@ static int xlgmac_rx_poll(struct xlgmac_channel *channel, int budget) > netif_err(pdata, rx_err, netdev, > "error in received packet\n"); > dev_kfree_skb(skb); > + skb = NULL; > goto next_packet; > } > > @@ -1227,6 +1228,7 @@ static int xlgmac_rx_poll(struct xlgmac_channel *channel, int budget) > netif_err(pdata, rx_err, netdev, > "packet length exceeds configured MTU\n"); > dev_kfree_skb(skb); > + skb = NULL; > goto next_packet; > } Same problem as your amd-xgbe patch, the condition you say can occurr is actually impossible.