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 03D69C4646D for ; Mon, 6 Aug 2018 15:08:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BA56D215A4 for ; Mon, 6 Aug 2018 15:08:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BA56D215A4 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 S1732593AbeHFRSL (ORCPT ); Mon, 6 Aug 2018 13:18:11 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:50034 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727541AbeHFRSK (ORCPT ); Mon, 6 Aug 2018 13:18:10 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D70F24015A45; Mon, 6 Aug 2018 15:08:38 +0000 (UTC) Received: from krava (unknown [10.43.17.214]) by smtp.corp.redhat.com (Postfix) with SMTP id B32C92026D74; Mon, 6 Aug 2018 15:08:36 +0000 (UTC) Date: Mon, 6 Aug 2018 17:08:36 +0200 From: Jiri Olsa To: Oleg Nesterov Cc: Jiri Olsa , Arnaldo Carvalho de Melo , Milind Chabbi , lkml , Ingo Molnar , Namhyung Kim , David Ahern , Alexander Shishkin , Peter Zijlstra , Frederic Weisbecker Subject: [PATCH 3/2] perf/hw_breakpoint: Remove superfluous bp->attr.disabled = 0 new attr has disabled set Message-ID: <20180806150836.GD16446@krava> References: <20180806101241.6444-1-jolsa@kernel.org> <20180806101241.6444-3-jolsa@kernel.org> <20180806124839.GC7840@redhat.com> <20180806132353.GA7463@krava> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180806132353.GA7463@krava> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Mon, 06 Aug 2018 15:08:38 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Mon, 06 Aug 2018 15:08:38 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'jolsa@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 06, 2018 at 03:23:53PM +0200, Jiri Olsa wrote: > On Mon, Aug 06, 2018 at 02:48:40PM +0200, Oleg Nesterov wrote: > > 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. > > > > yea, I was looking on that, but as u said it makes no difference > and I wanted to keep the patch as simple as possible ;-) > > I'll send something on top of this patch like this ;-) jirka --- Once the breakpoint was succesfully modified, the attr->disabled value is in bp->attr.disabled. So there's no reason to set it again, removing that. Link: http://lkml.kernel.org/n/tip-v5oaellzsmyszv3rfucuxkp0@git.kernel.org Signed-off-by: Jiri Olsa --- kernel/events/hw_breakpoint.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index fb229d9c7f3c..3e560d7609fd 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -526,10 +526,9 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att if (err) return err; - if (!attr->disabled) { + if (!attr->disabled) perf_event_enable(bp); - bp->attr.disabled = 0; - } + return 0; } EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint); -- 2.17.1