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 985DDC46471 for ; Mon, 6 Aug 2018 13:07:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4DF18218F0 for ; Mon, 6 Aug 2018 13:07:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4DF18218F0 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 S1730543AbeHFPQf (ORCPT ); Mon, 6 Aug 2018 11:16:35 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:60022 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727502AbeHFPQf (ORCPT ); Mon, 6 Aug 2018 11:16:35 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 643E440241C3; Mon, 6 Aug 2018 13:07:33 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.34.27.30]) by smtp.corp.redhat.com (Postfix) with SMTP id A33201049483; Mon, 6 Aug 2018 13:07:31 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 6 Aug 2018 15:07:33 +0200 (CEST) Date: Mon, 6 Aug 2018 15:07:31 +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: <20180806130730.GD7840@redhat.com> References: <20180806101241.6444-1-jolsa@kernel.org> <20180806101241.6444-3-jolsa@kernel.org> <20180806124839.GC7840@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180806124839.GC7840@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Mon, 06 Aug 2018 13:07:33 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Mon, 06 Aug 2018 13:07:33 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.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, Oleg Nesterov wrote: > > 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. I am looking at another caller perf_event_modify_breakpoint(). It too doesn't set attr.disabled = 1 on failure, it does _perf_event_enable() instead so attr.disabled should be correct. But this looks wrong. If modify_user_hw_breakpoint_check() paths fails after arch_validate_hwbkpt_settings() was called, then we can not simply restore bp_addr/bp_type/bp_len and do _perf_event_enable(). We need another modify_user_hw_breakpoint_check() or validate_hw_breakpoint(). Note that arch_validate_hwbkpt_settings() updates arch_hw_breakpoint according to bp.attr, the restored bp->attr.bp_addr/bp_typebp_len have no effect if we call _perf_event_enable() after the failure. Or I am totally confused? Oleg.