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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CC5F0C433F5 for ; Mon, 11 Oct 2021 08:51:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AD4C2603E7 for ; Mon, 11 Oct 2021 08:51:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235302AbhJKIx6 (ORCPT ); Mon, 11 Oct 2021 04:53:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50950 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235276AbhJKIx5 (ORCPT ); Mon, 11 Oct 2021 04:53:57 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7CA63C061570 for ; Mon, 11 Oct 2021 01:51:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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; bh=7YVymMd1SbIp4GGj6cvsViy3NVnVBW502IFSGTTc15g=; b=hC/2VI3bQPtweCVTvBVDOAPH2H opdczrNE5tbrFkVWctScNRc9NA1YZlHh4OGk1LNSSM4CJYsK9trCjmrPLeB9TSHlxDvls7kyOwf7D MsH2pqc8Y1wjwcCvzBU3nJlL5Vk9TpDgzKCbk2UCbEFbPFwPQVPqiah7GXDWrTxYsvW1E7NUnvBck od8/6qMrctyy5uTJZPyyFAowAm6aWYc6HAc0IGuOApG4gKoRbFYOyfNj3wypf5s25MExqRDjsg9sp /z0ppkyWA6NQMPY2cQDZ3aA4vpjLelQPcgAy3iinw/JysDFKyWPtmLcTNGlJZoSfmvCmsSHFYqTkM TlCWEjbA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mZqyy-005OkA-DM; Mon, 11 Oct 2021 08:48:51 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 67EBB3001E1; Mon, 11 Oct 2021 10:48:28 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 09ED72BFB0E3D; Mon, 11 Oct 2021 10:48:28 +0200 (CEST) Date: Mon, 11 Oct 2021 10:48:27 +0200 From: Peter Zijlstra To: =?utf-8?B?546L6LSH?= Cc: Steven Rostedt , Ingo Molnar , open list , Jiri Olsa Subject: Re: [RESEND PATCH v2] trace: prevent preemption in perf_ftrace_function_call() Message-ID: References: <20211008200328.5b88422d@oasis.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 11, 2021 at 10:32:46AM +0200, Peter Zijlstra wrote: > diff --git a/include/linux/trace_recursion.h b/include/linux/trace_recursion.h > index a9f9c5714e65..ca12e2d8e060 100644 > --- a/include/linux/trace_recursion.h > +++ b/include/linux/trace_recursion.h > @@ -214,7 +214,14 @@ static __always_inline void trace_clear_recursion(int bit) > static __always_inline int ftrace_test_recursion_trylock(unsigned long ip, > unsigned long parent_ip) > { > - return trace_test_and_set_recursion(ip, parent_ip, TRACE_FTRACE_START, TRACE_FTRACE_MAX); > + bool ret; > + > + preempt_disable_notrace(); > + ret = trace_test_and_set_recursion(ip, parent_ip, TRACE_FTRACE_START, TRACE_FTRACE_MAX); > + if (!ret) > + preempt_enable_notrace(); > + > + return ret; > } > > /** Oh, I might've gotten that wrong, I assumed regular trylock semantics, but it doesn't look like that's right.