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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 0FB8FC43381 for ; Mon, 18 Mar 2019 15:15:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C75E82085A for ; Mon, 18 Mar 2019 15:15:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="YBwIea3B" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727440AbfCRPPh (ORCPT ); Mon, 18 Mar 2019 11:15:37 -0400 Received: from merlin.infradead.org ([205.233.59.134]:58048 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726808AbfCRPPf (ORCPT ); Mon, 18 Mar 2019 11:15:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=mUzQztixUaL5Z4slN1bY3zTE9JHBDdO/8J2GDqOGk/k=; b=YBwIea3BEe1WeRICVkJVYW+Wr p21tyFVCHdLIV7YAFD3s83HnnVIycyFLIA2IFvTPAG9Z9SHy2xx5JiLs3qmws6RGsGVebR+L1eDDM H1YvdGuSo7tI9jJeFpnPs4FkNWOrzZ3HkrdpjLq3umhmT8y1qY6MuXos+W4ExfcxD06hNkEzrjSmV iMv8lOu8NR/QHZStDpwLDmyBPvt/XQt2DpR/zxM7BSGhyd69nObshbwkvYa0gjMi+hb5GX0d12X9e pwkTmWDhoJxP+3fVCz2XmQlXSJNVcBsl3UzelzZDlTFcDkE/Oh6bEXng6oSdmixnLfTOv5jgpfaZl EQh0YuNZg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1h5tz8-0004hQ-M2; Mon, 18 Mar 2019 15:15:30 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 4E7002021950E; Mon, 18 Mar 2019 16:15:29 +0100 (CET) Date: Mon, 18 Mar 2019 16:15:29 +0100 From: Peter Zijlstra To: Steven Rostedt Cc: Prateek Sood , mingo@redhat.com, linux-kernel@vger.kernel.org, sramana@codeaurora.org, Frederic Weisbecker , Jiri Olsa Subject: Re: [PATCH] perf: extend total_ref_count usage to protect perf_trace_buf access Message-ID: <20190318151529.GT6058@hirez.programming.kicks-ass.net> References: <1552906065-24137-1-git-send-email-prsood@codeaurora.org> <20190318110250.7214cfa7@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190318110250.7214cfa7@gandalf.local.home> 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 Mon, Mar 18, 2019 at 11:02:50AM -0400, Steven Rostedt wrote: > On Mon, 18 Mar 2019 16:17:45 +0530 > Prateek Sood wrote: > > > A potential race exists between access of perf_trace_buf[i] from > > perf_trace_buf_alloc() and perf_trace_event_unreg(). This can > > result in perf_trace_buf[i] being NULL during access from memset() > > in perf_trace_buf_alloc(). Can you expound?