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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 6E8E6C4321D for ; Tue, 21 Aug 2018 11:36:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2BE7521473 for ; Tue, 21 Aug 2018 11:36:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2BE7521473 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=canonical.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 S1727051AbeHUO41 (ORCPT ); Tue, 21 Aug 2018 10:56:27 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:40081 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726798AbeHUO41 (ORCPT ); Tue, 21 Aug 2018 10:56:27 -0400 Received: from 1.general.cking.uk.vpn ([10.172.193.212] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1fs4xe-0007rQ-HM; Tue, 21 Aug 2018 11:36:34 +0000 From: Colin King To: Andrew Morton , "Kirill A . Shutemov" , "Michael S . Tsirkin" , linux-mm@kvack.org Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] mm/gup_benchmark: fix unsigned comparison with less than zero Date: Tue, 21 Aug 2018 12:36:34 +0100 Message-Id: <20180821113634.3782-1-colin.king@canonical.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Colin Ian King Currently the return from get_user_pages_fast is being checked to be less than zero for an error check, however, the variable being checked is unsigned so the check is always false. Fix this by using a signed long instead. Detected by Coccinelle ("Unsigned expression compared with zero: nr <= 0") Fixes: 64c349f4ae78 ("mm: add infrastructure for get_user_pages_fast() benchmarking") Signed-off-by: Colin Ian King --- mm/gup_benchmark.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/mm/gup_benchmark.c b/mm/gup_benchmark.c index 6a473709e9b6..a9a15e7a1185 100644 --- a/mm/gup_benchmark.c +++ b/mm/gup_benchmark.c @@ -31,6 +31,8 @@ static int __gup_benchmark_ioctl(unsigned int cmd, nr = gup->nr_pages_per_call; start_time = ktime_get(); for (addr = gup->addr; addr < gup->addr + gup->size; addr = next) { + long n; + if (nr != gup->nr_pages_per_call) break; @@ -40,10 +42,10 @@ static int __gup_benchmark_ioctl(unsigned int cmd, nr = (next - addr) / PAGE_SIZE; } - nr = get_user_pages_fast(addr, nr, gup->flags & 1, pages + i); - if (nr <= 0) + n = get_user_pages_fast(addr, nr, gup->flags & 1, pages + i); + if (n <= 0) break; - i += nr; + i += n; } end_time = ktime_get(); -- 2.17.1