From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752772Ab1ARQRz (ORCPT ); Tue, 18 Jan 2011 11:17:55 -0500 Received: from mx1.redhat.com ([209.132.183.28]:21385 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752735Ab1ARQRy (ORCPT ); Tue, 18 Jan 2011 11:17:54 -0500 Date: Tue, 18 Jan 2011 17:10:08 +0100 From: Oleg Nesterov To: Peter Zijlstra Cc: Alan Stern , Arnaldo Carvalho de Melo , Frederic Weisbecker , Ingo Molnar , Paul Mackerras , Prasad , Roland McGrath , gregkh@suse.de, linux-kernel@vger.kernel.org, stable@kernel.org Subject: [PATCH 1/2] perf: find_get_context: fix the per-cpu-counter check Message-ID: <20110118161008.GB693@redhat.com> References: <20101108145647.GA3426@redhat.com> <20110117203459.GA32700@redhat.com> <1295297576.30950.382.camel@laptop> <20110118160942.GA693@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110118160942.GA693@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If task == NULL, find_get_context() should always check that cpu is correct. Afaics, the bug was introduced by 38a81da2 "perf events: Clean up pid passing", but even before that commit "&& cpu != -1" was not exactly right, -ESRCH from find_task_by_vpid() is not accurate. Signed-off-by: Oleg Nesterov --- kernel/perf_event.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- git/kernel/perf_event.c~1_find_get_context 2011-01-14 18:21:05.000000000 +0100 +++ git/kernel/perf_event.c 2011-01-18 16:56:40.000000000 +0100 @@ -2228,7 +2228,7 @@ find_get_context(struct pmu *pmu, struct unsigned long flags; int ctxn, err; - if (!task && cpu != -1) { + if (!task) { /* Must be root to operate on a CPU event: */ if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN)) return ERR_PTR(-EACCES);