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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id 138B7C07D5C for ; Thu, 14 Jun 2018 14:10:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C80F2208DD for ; Thu, 14 Jun 2018 14:10:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C80F2208DD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.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 S965685AbeFNOKn (ORCPT ); Thu, 14 Jun 2018 10:10:43 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:59740 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965656AbeFNOKj (ORCPT ); Thu, 14 Jun 2018 10:10:39 -0400 Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w5EE5DnH059356 for ; Thu, 14 Jun 2018 10:10:39 -0400 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0b-001b2d01.pphosted.com with ESMTP id 2jkst6reqb-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 14 Jun 2018 10:10:38 -0400 Received: from localhost by e06smtp02.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 14 Jun 2018 15:10:33 +0100 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w5EEAWYG23265424 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 14 Jun 2018 14:10:32 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E823CAE053; Thu, 14 Jun 2018 14:59:20 +0100 (BST) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 786E1AE058; Thu, 14 Jun 2018 14:59:20 +0100 (BST) Received: from oc3784624756.ibm.com (unknown [9.152.212.222]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 14 Jun 2018 14:59:20 +0100 (BST) Subject: Re: [PATCH 1/3] perf alias: Remove trailing newline when reading sysfs files To: Paul Clarke , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, acme@kernel.org, jolsa@redhat.com Cc: brueckner@linux.vnet.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com References: <20180614114845.41221-1-tmricht@linux.ibm.com> From: Thomas-Mich Richter Organization: IBM LTC Date: Thu, 14 Jun 2018 16:10:31 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 18061414-0008-0000-0000-00000247B6EE X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18061414-0009-0000-0000-000021ADED31 Message-Id: <3c66953b-fb56-e446-8dff-53fd91007a43@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-06-14_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1805220000 definitions=main-1806140156 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/14/2018 03:17 PM, Paul Clarke wrote: > On 06/14/2018 06:48 AM, Thomas Richter wrote: >> Remove a trailing newline when reading sysfs file contents >> such as /sys/devices/cpum_cf/events/TX_NC_TEND. >> This show when verbose option -v is used. >> >> Output before: >> tx_nc_tend -> 'cpum_cf'/'event=0x008d >> '/ >> >> Output after: >> tx_nc_tend -> 'cpum_cf'/'event=0x8d'/ >> >> Signed-off-by: Thomas Richter >> --- >> tools/perf/util/pmu.c | 7 ++++++- >> 1 file changed, 6 insertions(+), 1 deletion(-) >> >> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c >> index 7878934ebb23..26c79a9c4142 100644 >> --- a/tools/perf/util/pmu.c >> +++ b/tools/perf/util/pmu.c >> @@ -294,7 +294,7 @@ static int __perf_pmu__new_alias(struct list_head *list, char *dir, char *name, >> >> static int perf_pmu__new_alias(struct list_head *list, char *dir, char *name, FILE *file) >> { >> - char buf[256]; >> + char *cp, buf[256]; >> int ret; >> >> ret = fread(buf, 1, sizeof(buf), file); >> @@ -303,6 +303,11 @@ static int perf_pmu__new_alias(struct list_head *list, char *dir, char *name, FI >> >> buf[ret] = 0; >> >> + /* Remove trailing newline from sysfs file */ >> + cp = strrchr(buf, '\n'); >> + if (cp) >> + *cp = '\0'; > > A nit, perhaps, but this will search backwards through the entire string if a newline is not found, which is the most common case, I presume. Would it be more efficient to just look at the last character? Something like: > i = strlen(buf); > if (i > 0 && buf[i-1] == '\n') > buf[i-1] = '\0'; > >> + >> return __perf_pmu__new_alias(list, dir, name, NULL, buf, NULL, NULL, NULL, >> NULL, NULL, NULL); >> } >> > > PC > Arnaldo suggested rtrim() which I will use. I agree that your approach is a bit faster... -- Thomas Richter, Dept 3303, IBM s390 Linux Development, Boeblingen, Germany -- Vorsitzende des Aufsichtsrats: Martina Koederitz Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294