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=-2.5 required=3.0 tests=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 D105EC4646D for ; Mon, 6 Aug 2018 12:48:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 860C52178F for ; Mon, 6 Aug 2018 12:48:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 860C52178F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732248AbeHFO5l (ORCPT ); Mon, 6 Aug 2018 10:57:41 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:45388 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727561AbeHFO5k (ORCPT ); Mon, 6 Aug 2018 10:57:40 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BD6CC402243B; Mon, 6 Aug 2018 12:48:42 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.34.27.30]) by smtp.corp.redhat.com (Postfix) with SMTP id ED3B21C4C3; Mon, 6 Aug 2018 12:48:40 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 6 Aug 2018 14:48:42 +0200 (CEST) Date: Mon, 6 Aug 2018 14:48:40 +0200 From: Oleg Nesterov To: Jiri Olsa Cc: Arnaldo Carvalho de Melo , Milind Chabbi , lkml , Ingo Molnar , Namhyung Kim , David Ahern , Alexander Shishkin , Peter Zijlstra , Frederic Weisbecker Subject: Re: [PATCH 2/2] perf/hw_breakpoint: Modify breakpoint even if the new attr has disabled set Message-ID: <20180806124839.GC7840@redhat.com> References: <20180806101241.6444-1-jolsa@kernel.org> <20180806101241.6444-3-jolsa@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180806101241.6444-3-jolsa@kernel.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Mon, 06 Aug 2018 12:48:42 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Mon, 06 Aug 2018 12:48:42 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'oleg@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/06, Jiri Olsa wrote: > > We need to change the breakpoint even if the attr with > new fields has disabled set to true. Agreed... The patch looks fine to me, but I have a question > int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr) > { > + int err; > + > /* > * modify_user_hw_breakpoint can be invoked with IRQs disabled and hence it > * will not be possible to raise IPIs that invoke __perf_event_disable. > @@ -520,11 +522,11 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att > else > perf_event_disable(bp); > > - if (!attr->disabled) { > - int err = modify_user_hw_breakpoint_check(bp, attr, false); > + err = modify_user_hw_breakpoint_check(bp, attr, false); > + if (err) > + return err; > > - if (err) > - return err; > + if (!attr->disabled) { > perf_event_enable(bp); > bp->attr.disabled = 0; Afaics you do not need to clear attr.disabled, modify_user_hw_breakpoint_check() updates it if err = 0. So I think if (!bp->attr.disabled) perf_event_enable(bp); will look a bit better. But, with or without this fix, shouldn't we set .disabled = 1 if modify_() fails? IIUC this doesn't matter, bp->attr.disabled is not really used anyway, but looks a bit confusing. Oleg.