From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754873AbbBMUwQ (ORCPT ); Fri, 13 Feb 2015 15:52:16 -0500 Received: from mail.kernel.org ([198.145.29.136]:37628 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753215AbbBMUwM (ORCPT ); Fri, 13 Feb 2015 15:52:12 -0500 From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Kaixu Xia , Peter Zijlstra , Paul Mackerras , Arnaldo Carvalho de Melo Subject: [PATCH 38/43] perf: Remove the extra validity check on nr_pages Date: Fri, 13 Feb 2015 17:49:27 -0300 Message-Id: <1423860572-24881-39-git-send-email-acme@kernel.org> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1423860572-24881-1-git-send-email-acme@kernel.org> References: <1423860572-24881-1-git-send-email-acme@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kaixu Xia The function is_power_of_2() also do the check on nr_pages, so the first check performed is unnecessary. On the other hand, the key point is to ensure @nr_pages is a power-of-two number and mostly @nr_pages is a nonzero value, so in the most cases, the function is_power_of_2() will be called. Signed-off-by: Kaixu Xia Cc: Peter Zijlstra Cc: Paul Mackerras Link: http://lkml.kernel.org/r/1422352512-75150-1-git-send-email-xiakaixu@huawei.com Signed-off-by: Arnaldo Carvalho de Melo --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 7f2fbb8b5069..0969c9b67eec 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4420,7 +4420,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) * If we have rb 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)) + if (!is_power_of_2(nr_pages)) return -EINVAL; if (vma_size != PAGE_SIZE * (1 + nr_pages)) -- 1.9.3