From patchwork Thu Oct 29 11:34:48 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yunsheng Lin X-Patchwork-Id: 1390079 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=none (p=none dis=none) header.from=huawei.com Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4CMNjy0vHGz9sTD for ; Thu, 29 Oct 2020 22:38:30 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725846AbgJ2Li3 (ORCPT ); Thu, 29 Oct 2020 07:38:29 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:6988 "EHLO szxga06-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725773AbgJ2Li2 (ORCPT ); Thu, 29 Oct 2020 07:38:28 -0400 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.60]) by szxga06-in.huawei.com (SkyGuard) with ESMTP id 4CMNjv3XvxzhdFv; Thu, 29 Oct 2020 19:38:27 +0800 (CST) Received: from localhost.localdomain (10.69.192.58) by DGGEMS405-HUB.china.huawei.com (10.3.19.205) with Microsoft SMTP Server id 14.3.487.0; Thu, 29 Oct 2020 19:38:16 +0800 From: Yunsheng Lin To: , , , , , , , , , , , , , CC: , , Subject: [PATCH net-next] net: add in_softirq() debug checking in napi_consume_skb() Date: Thu, 29 Oct 2020 19:34:48 +0800 Message-ID: <1603971288-4786-1-git-send-email-linyunsheng@huawei.com> X-Mailer: git-send-email 2.8.1 MIME-Version: 1.0 X-Originating-IP: [10.69.192.58] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The current semantic for napi_consume_skb() is that caller need to provide non-zero budget when calling from NAPI context, and breaking this semantic will cause hard to debug problem, because _kfree_skb_defer() need to run in atomic context in order to push the skb to the particular cpu' napi_alloc_cache atomically. So add a in_softirq() debug checking in napi_consume_skb() to catch this kind of error. Suggested-by: Eric Dumazet Signed-off-by: Yunsheng Lin --- v1: drop RFC in the title --- include/linux/netdevice.h | 6 ++++++ net/Kconfig | 7 +++++++ net/core/skbuff.c | 4 ++++ 3 files changed, 17 insertions(+) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 964b494..8042bf1 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -5158,6 +5158,12 @@ do { \ }) #endif +#if defined(CONFIG_DEBUG_NET) +#define DEBUG_NET_WARN(condition, ...) WARN(condition, ##__VA_ARGS__) +#else +#define DEBUG_NET_WARN(condition, ...) +#endif + /* * The list of packet types we will receive (as opposed to discard) * and the routines to invoke. diff --git a/net/Kconfig b/net/Kconfig index d656716..82e69b0 100644 --- a/net/Kconfig +++ b/net/Kconfig @@ -459,6 +459,13 @@ config ETHTOOL_NETLINK netlink. It provides better extensibility and some new features, e.g. notification messages. +config DEBUG_NET + bool "Net debugging and diagnostics" + depends on DEBUG_KERNEL + default n + help + Say Y here to add some extra checks and diagnostics to networking. + endif # if NET # Used by archs to tell that they support BPF JIT compiler plus which flavour. diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 1ba8f01..1834007 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -897,6 +897,10 @@ void napi_consume_skb(struct sk_buff *skb, int budget) return; } + DEBUG_NET_WARN(!in_softirq(), + "%s is called with non-zero budget outside softirq context.\n", + __func__); + if (!skb_unref(skb)) return;