From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755296AbbLKRPm (ORCPT ); Fri, 11 Dec 2015 12:15:42 -0500 Received: from mga11.intel.com ([192.55.52.93]:27638 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752288AbbLKRPl (ORCPT ); Fri, 11 Dec 2015 12:15:41 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,414,1444719600"; d="scan'208";a="839349996" From: Alexander Shishkin To: Peter Zijlstra Cc: Ingo Molnar , linux-kernel@vger.kernel.org, vince@deater.net, eranian@google.com, Arnaldo Carvalho de Melo , Mathieu Poirier Subject: Re: [PATCH v0 3/5] perf: Introduce instruction trace filtering In-Reply-To: <20151211165904.GB6356@twins.programming.kicks-ass.net> References: <1449840998-29902-1-git-send-email-alexander.shishkin@linux.intel.com> <1449840998-29902-4-git-send-email-alexander.shishkin@linux.intel.com> <20151211165904.GB6356@twins.programming.kicks-ass.net> User-Agent: Notmuch/0.21 (http://notmuchmail.org) Emacs/24.5.1 (x86_64-pc-linux-gnu) Date: Fri, 11 Dec 2015 19:15:37 +0200 Message-ID: <87bn9wykhy.fsf@ashishki-desk.ger.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Peter Zijlstra writes: > On Fri, Dec 11, 2015 at 03:36:36PM +0200, Alexander Shishkin wrote: >> +static int >> +perf_event_set_itrace_filter(struct perf_event *event, char *filter_str) >> +{ >> + int ret = 0; >> + >> + /* >> + * Since this is called in perf_ioctl() path, we're already holding >> + * ctx::mutex. >> + */ >> + lockdep_assert_held(&event->ctx->mutex); >> + >> + /* >> + * For now, we only support filtering in per-task events; doing so >> + * for cpu-wide events requires additional context switching trickery, >> + * since same object code will be mapped at different virtual >> + * addresses in different processes. >> + */ >> + if (!event->ctx->task) >> + return -EOPNOTSUPP; >> + >> + /* remove existing filters, if any */ >> + perf_itrace_filters_clear(event); >> + >> + ret = perf_event_parse_itrace_filter(event, filter_str); >> + if (!ret) { >> + perf_itrace_filters_apply(event); >> + >> + ret = perf_event_itrace_filters_setup(event); >> + if (ret) >> + perf_itrace_filters_clear(event); > > This is what I meant, if you try and set a 'wrong' filter while it > already has filters set, you'll not only error out, you'll also wipe the > current state. > > This seems wrong. Ah, now I see what you mean. Yes, you're right. Regards, -- Alex