From patchwork Tue Nov 24 10:49:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yunsheng Lin X-Patchwork-Id: 11927923 X-Patchwork-Delegate: kuba@kernel.org 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 A4D41C63798 for ; Tue, 24 Nov 2020 10:53:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C47A2083E for ; Tue, 24 Nov 2020 10:53:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732286AbgKXKxP (ORCPT ); Tue, 24 Nov 2020 05:53:15 -0500 Received: from szxga06-in.huawei.com ([45.249.212.32]:7977 "EHLO szxga06-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731944AbgKXKxO (ORCPT ); Tue, 24 Nov 2020 05:53:14 -0500 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.60]) by szxga06-in.huawei.com (SkyGuard) with ESMTP id 4CgLTN6W6Wzhd5x; Tue, 24 Nov 2020 18:52:56 +0800 (CST) Received: from localhost.localdomain (10.69.192.58) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.487.0; Tue, 24 Nov 2020 18:53:02 +0800 From: Yunsheng Lin To: , , , , , , , , , , , , , , , , CC: , , Subject: [PATCH net-next v3 1/2] lockdep: Introduce in_softirq lockdep assert Date: Tue, 24 Nov 2020 18:49:28 +0800 Message-ID: <1606214969-97849-2-git-send-email-linyunsheng@huawei.com> X-Mailer: git-send-email 2.8.1 In-Reply-To: <1606214969-97849-1-git-send-email-linyunsheng@huawei.com> References: <1606214969-97849-1-git-send-email-linyunsheng@huawei.com> 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 X-Patchwork-Delegate: kuba@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 the lockdep_assert_in_softirq() to assert when the running context is not in_softirq, in_softirq means softirq is serving or BH is disabled, which has a ambiguous semantics due to the BH disabled confusion, so add a comment to emphasize that. And the softirq context can be interrupted by hard IRQ or NMI context, lockdep_assert_in_softirq() need to assert about hard IRQ or NMI context too. Suggested-by: Jakub Kicinski Signed-off-by: Yunsheng Lin --- V3: add comment to emphasize the ambiguous semantics. --- include/linux/lockdep.h | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index f559487..8d60f46 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -594,6 +594,13 @@ do { \ this_cpu_read(hardirqs_enabled))); \ } while (0) +/* Much like in_softirq() - semantics are ambiguous, use carefully. */ +#define lockdep_assert_in_softirq() \ +do { \ + WARN_ON_ONCE(__lockdep_enabled && \ + (!in_softirq() || in_irq() || in_nmi())); \ +} while (0) + #else # define might_lock(lock) do { } while (0) # define might_lock_read(lock) do { } while (0) @@ -605,6 +612,7 @@ do { \ # define lockdep_assert_preemption_enabled() do { } while (0) # define lockdep_assert_preemption_disabled() do { } while (0) +# define lockdep_assert_in_softirq() do { } while (0) #endif #ifdef CONFIG_PROVE_RAW_LOCK_NESTING