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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 D3D88C2D0DB for ; Wed, 29 Jan 2020 22:19:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A50B820716 for ; Wed, 29 Jan 2020 22:19:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="L0wTNSd/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726774AbgA2WTL (ORCPT ); Wed, 29 Jan 2020 17:19:11 -0500 Received: from mail-pj1-f65.google.com ([209.85.216.65]:38665 "EHLO mail-pj1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726222AbgA2WTL (ORCPT ); Wed, 29 Jan 2020 17:19:11 -0500 Received: by mail-pj1-f65.google.com with SMTP id j17so432738pjz.3 for ; Wed, 29 Jan 2020 14:19:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=gm6baxWqlVJBYjrTuitTNaBr1MkKZDLEKcjPTz92Yuw=; b=L0wTNSd/ba+/Jir8Y8zAOCd7bzmaRvQDYfPfI8/l5zQ/mCR76l00gBEDLWTaLHWYed oJM+kdxg6sizMD60HCiFYaoJapHuqErPhDUoNTBNc3XtG4v/jLGEqonFFwajIcmS5S8H rn1JDRJEIgVmwOZqhTfq8qfszi6iq44EBMiW0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=gm6baxWqlVJBYjrTuitTNaBr1MkKZDLEKcjPTz92Yuw=; b=BKqptmQz1zlhbDEnUZo2Yt6bZLE+m1dBBmUKM01FpFSsCNBByC3SaZI2tnoBAtQaHu sI9X9DZmcmrvd/eBsI/JSPuikgE/a4Kjg2aZVPfGYdBXI+S7oj9rO6pYzGqQPRKlz9ri kHTPlueLzJ7Ce6xaN2u+/AL6A97iv1q4q9xCGbzwrDJ73RDwH1IN2kIYfBXUFvdnnTfr +WaKaKsmYi7IS8QLnditClNCCdonL0381nk+vICOIAeixBCYEJJLiaFOSFy9L3jKVkjH UlzFXZm1uJFEqyFfqOksm+fXclbOfrEpuLWbPy6k+7rsLgc4P3E67HMsBRfnqzCzppej zXxw== X-Gm-Message-State: APjAAAUNxQ/YlU/twU0rlam7yGjqT9SJWfU+7kccDf9YB6jd80CLYIQN 7qeM6dQ6xtmBraAQiaopiWs2jQ== X-Google-Smtp-Source: APXvYqyVTFJ4QGYL+Go0ew04cMV55S2wewIfTCwD5Ah3U4M1HkXDKHhZSGpRe9nEJkt5UHJBefNCPA== X-Received: by 2002:a17:90a:3243:: with SMTP id k61mr2157855pjb.43.1580336350700; Wed, 29 Jan 2020 14:19:10 -0800 (PST) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id gx2sm3676730pjb.18.2020.01.29.14.19.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Jan 2020 14:19:10 -0800 (PST) Date: Wed, 29 Jan 2020 17:19:09 -0500 From: Joel Fernandes To: Amol Grover Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, Madhuparna Bhowmik , "Paul E . McKenney" Subject: Re: [PATCH 2/2] events: callchain: Use RCU API to access RCU pointer Message-ID: <20200129221909.GA74354@google.com> References: <20200129160813.14263-1-frextrite@gmail.com> <20200129160813.14263-2-frextrite@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200129160813.14263-2-frextrite@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 29, 2020 at 09:38:13PM +0530, Amol Grover wrote: > callchain_cpus_entries is annotated as an RCU pointer. > Hence rcu_dereference_protected or similar RCU API is > required to dereference the pointer. > > This fixes the following sparse warning > kernel/events/callchain.c:65:17: warning: incorrect type in assignment > > Signed-off-by: Amol Grover > --- > kernel/events/callchain.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c > index f91e1f41d25d..a672d02a1b3a 100644 > --- a/kernel/events/callchain.c > +++ b/kernel/events/callchain.c > @@ -62,7 +62,8 @@ static void release_callchain_buffers(void) > { > struct callchain_cpus_entries *entries; > > - entries = callchain_cpus_entries; > + entries = rcu_dereference_protected(callchain_cpus_entries, > + lockdep_is_held(&callchain_mutex)); Reviewed-by: Joel Fernandes (Google) thanks, - Joel > RCU_INIT_POINTER(callchain_cpus_entries, NULL); > call_rcu(&entries->rcu_head, release_callchain_buffers_rcu); > } > -- > 2.24.1 >