From patchwork Wed Sep 16 18:45:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jakub Kicinski X-Patchwork-Id: 1365617 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=kernel.org Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=default header.b=2h1IaLXp; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BsJ0k0pD3zB3wd for ; Thu, 17 Sep 2020 10:35:50 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728191AbgIPSrL (ORCPT ); Wed, 16 Sep 2020 14:47:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:44358 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727957AbgIPSqQ (ORCPT ); Wed, 16 Sep 2020 14:46:16 -0400 Received: from kicinski-fedora-PC1C0HJN.thefacebook.com (unknown [163.114.132.4]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0FCEE22208; Wed, 16 Sep 2020 18:46:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600281970; bh=TidjB1CLdcHX17GrkijsFnb24uaNGbCHwZRDDig+Y9A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2h1IaLXpkde6U5QpHfMM0BRR77jj/AELrC+lj88srCPwLmXW+wzgJA08rPiwPbux3 2qKyU+fnNTuAGlAv6O3X9UBYTrAaSwa7qyi1DUwDz2P93eXDV4Iz84mrp0u9aBwqT6 TF6rg7ltPV+zZIbreI1xFlhUVv2eRUIVwCD8bdeU= From: Jakub Kicinski To: davem@davemloft.net, paulmck@kernel.org, joel@joelfernandes.org Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, josh@joshtriplett.org, peterz@infradead.org, christian.brauner@ubuntu.com, Jakub Kicinski , rostedt@goodmis.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com Subject: [PATCH net-next 7/7] rcu: prevent RCU_LOCKDEP_WARN() from swallowing the condition Date: Wed, 16 Sep 2020 11:45:28 -0700 Message-Id: <20200916184528.498184-8-kuba@kernel.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200916184528.498184-1-kuba@kernel.org> References: <20200916184528.498184-1-kuba@kernel.org> MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org We run into a unused variable warning in bridge code when variable is only used inside the condition of rcu_dereference_protected(). #define mlock_dereference(X, br) \ rcu_dereference_protected(X, lockdep_is_held(&br->multicast_lock)) Since on builds with CONFIG_PROVE_RCU=n rcu_dereference_protected() compiles to nothing the compiler doesn't see the variable use. Prevent the warning by adding the condition as dead code. Signed-off-by: Jakub Kicinski --- CC: paulmck@kernel.org CC: josh@joshtriplett.org CC: rostedt@goodmis.org CC: mathieu.desnoyers@efficios.com CC: joel@joelfernandes.org CC: jiangshanlai@gmail.com --- include/linux/rcupdate.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 53f9648cb982..50d45781fa99 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -321,7 +321,7 @@ static inline void rcu_preempt_sleep_check(void) { } #else /* #ifdef CONFIG_PROVE_RCU */ -#define RCU_LOCKDEP_WARN(c, s) do { } while (0) +#define RCU_LOCKDEP_WARN(c, s) do { } while (0 && (c)) #define rcu_sleep_check() do { } while (0) #endif /* #else #ifdef CONFIG_PROVE_RCU */