Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761241AbZCYMJf (ORCPT ); Wed, 25 Mar 2009 08:09:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760437AbZCYMIF (ORCPT ); Wed, 25 Mar 2009 08:08:05 -0400 Received: from hera.kernel.org ([140.211.167.34]:57146 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760926AbZCYMID (ORCPT ); Wed, 25 Mar 2009 08:08:03 -0400 Date: Wed, 25 Mar 2009 12:07:20 GMT From: Peter Zijlstra To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, paulus@samba.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, paulus@samba.org, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <1237981712.7972.812.camel@twins> References: <1237981712.7972.812.camel@twins> Subject: [tip:perfcounters/core] perf_counter: allow and require one-page mmap on counting counters Message-ID: Git-Commit-ID: bb0ad4e22511e7caa715362945ad0766c7cca37e X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Wed, 25 Mar 2009 12:07:22 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1651 Lines: 44 Commit-ID: bb0ad4e22511e7caa715362945ad0766c7cca37e Gitweb: http://git.kernel.org/tip/bb0ad4e22511e7caa715362945ad0766c7cca37e Author: Peter Zijlstra AuthorDate: Wed, 25 Mar 2009 12:48:31 +0100 Committer: Ingo Molnar CommitDate: Wed, 25 Mar 2009 13:02:54 +0100 perf_counter: allow and require one-page mmap on counting counters A brainfart stopped single page mmap()s working. The rest of the code should be perfectly fine with not having any data pages. Reported-by: Paul Mackerras Signed-off-by: Peter Zijlstra LKML-Reference: <1237981712.7972.812.camel@twins> Signed-off-by: Ingo Molnar --- kernel/perf_counter.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-) diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index f3e1b27..95e0257 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -1369,7 +1369,11 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) vma_size = vma->vm_end - vma->vm_start; nr_pages = (vma_size / PAGE_SIZE) - 1; - if (nr_pages == 0 || !is_power_of_2(nr_pages)) + /* + * If we have data pages ensure they're a power-of-two number, so we + * can do bitmasks instead of modulo. + */ + if (nr_pages != 0 && !is_power_of_2(nr_pages)) return -EINVAL; if (vma_size != PAGE_SIZE * (1 + nr_pages)) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/