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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 23FFBC433FE for ; Sat, 9 Apr 2022 01:22:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230331AbiDIBYl (ORCPT ); Fri, 8 Apr 2022 21:24:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51026 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237706AbiDIBYj (ORCPT ); Fri, 8 Apr 2022 21:24:39 -0400 Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B60B02C650 for ; Fri, 8 Apr 2022 18:22:33 -0700 (PDT) Received: by mail-pj1-x102d.google.com with SMTP id ku13-20020a17090b218d00b001ca8fcd3adeso13383068pjb.2 for ; Fri, 08 Apr 2022 18:22:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=I0F2P2ML/pBi824KYgTw5KU1Y45bJmTHodkEFj/msPE=; b=rnIIkb90V9I9bcpVMa5/w0cTf4Gar8GVFDke+JSlU2hEHFp3OsRcTAqk7dfPeFG8tF dDExEmFCxiNoVK2EMa1ylHUlmv7DSThq6XmiX4TNJLDsXoKoUElD/mYy3ENP5lUCX6Cm L0cqaNurq1CWtLL/S3jZRhd8I253TJx1CfvGJLV8g4b2GyGGXfVeqwYyZcNtCYqWoaTJ rljgm3m6gGpplEG1geT3BvdWqZgCrGRUG3e99TyERwVqbDQLP1p54prwkHbmcNQHKk4J 2yNkYps6CqNhbHgl2xIZXaESlcelXNqaHtoVajN8GB4WEs0RS7UrQYqzpjddvSoSRqdi sZ6Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=I0F2P2ML/pBi824KYgTw5KU1Y45bJmTHodkEFj/msPE=; b=qlXSy2q4JuPJPMerOR/JPZn1F3Fa6yIjRXuXjnEXxXMfvt5ycvF/hkvh8sSNp15vI7 WdAuRE2JUgpOLy0qkraNlFPEgYaRfXOhF+4w1bkz18KIwRZi7mFnOFC4PbbLwRZXRGi1 STZFUcg2eYPxtMiry7jdcKku9R3/1+pkWWjespEIQnX6yRb6WZ/Yx3BogRd+Q5sPEemB CEu+iRXW5rlm+VCT0mk5CU8lf8Lw8oFkk8ClD6uXjL+09WCcN6xCsekwwZXmgJ0tP2cw EK6tOfWvRgAxSxF1gfXMJKzAV30v77VHIG86fXGYAhbRUKu5GwpNdM+K2Hn+y+2sLYWD EE6A== X-Gm-Message-State: AOAM530ENwqJ5IVSEjAwt2cmDByscWp6TxoPdRZ0/5hmQvQrJVH3XbfQ 96HxN496pDKVgPDEDcAWdMziEp2Pifx5snRbBkIRFQ== X-Google-Smtp-Source: ABdhPJyJCUjj5J7R135dzSPAdcxIjuPzJmPklzIABqKF59nyK/U0cF2KfJdhnRS2Ev/Kou5gxn1s4+XTYi7R+kW7BNM= X-Received: by 2002:a17:90b:3886:b0:1c7:c935:4447 with SMTP id mu6-20020a17090b388600b001c7c9354447mr25107776pjb.196.1649467351747; Fri, 08 Apr 2022 18:22:31 -0700 (PDT) MIME-Version: 1.0 References: <20220408045743.1432968-1-yosryahmed@google.com> <20220408045743.1432968-3-yosryahmed@google.com> In-Reply-To: <20220408045743.1432968-3-yosryahmed@google.com> From: Yosry Ahmed Date: Fri, 8 Apr 2022 18:21:55 -0700 Message-ID: Subject: Re: [PATCH v3 2/4] selftests: cgroup: return the errno of write() in cg_write() on failure To: Johannes Weiner , Michal Hocko , Shakeel Butt , Andrew Morton , Roman Gushchin Cc: David Rientjes , Tejun Heo , Zefan Li , Jonathan Corbet , Shuah Khan , Yu Zhao , Dave Hansen , Wei Xu , Greg Thelen , Chen Wandun , Vaibhav Jain , =?UTF-8?Q?Michal_Koutn=C3=BD?= , Tim Chen , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, Linux Kernel Mailing List , Linux-MM , linux-kselftest@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Thu, Apr 7, 2022 at 9:57 PM Yosry Ahmed wrote: > > Currently, cg_write() returns 0 on success and -1 on failure. Modify it > to return the errno of write() syscall when write() fails. > > Signed-off-by: Yosry Ahmed > --- > tools/testing/selftests/cgroup/cgroup_util.c | 32 +++++++++++--------- > 1 file changed, 17 insertions(+), 15 deletions(-) > > diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c > index dbaa7aabbb4a..3b6bb09985fa 100644 > --- a/tools/testing/selftests/cgroup/cgroup_util.c > +++ b/tools/testing/selftests/cgroup/cgroup_util.c > @@ -38,23 +38,23 @@ static ssize_t read_text(const char *path, char *buf, size_t max_len) > return len; > } > > -static ssize_t write_text(const char *path, char *buf, ssize_t len) > +/* > + * Returns: > + * success -> 0 > + * open() failure -> -1 > + * write() failure -> errno > + */ > +static int write_text(const char *path, char *buf, ssize_t len) > { > - int fd; > + int fd, ret; > > fd = open(path, O_WRONLY | O_APPEND); > if (fd < 0) > return fd; > > - len = write(fd, buf, len); > - if (len < 0) { > - close(fd); > - return len; > - } > - > + ret = write(fd, buf, len) < 0 ? errno : 0; > close(fd); > - > - return len; > + return ret; > } > > char *cg_name(const char *root, const char *name) > @@ -177,17 +177,19 @@ long cg_read_lc(const char *cgroup, const char *control) > return cnt; > } > > +/* > + * Returns: > + * success -> 0 > + * open() failure -> -1 > + * write() failure -> errno > + */ > int cg_write(const char *cgroup, const char *control, char *buf) > { > char path[PATH_MAX]; > ssize_t len = strlen(buf); > > snprintf(path, sizeof(path), "%s/%s", cgroup, control); > - > - if (write_text(path, buf, len) == len) > - return 0; > - > - return -1; > + return write_text(path, buf, len); > } I have changed this in v4 to a cleaner implementation that either returns 0 on success or -errno on failure. I also made sure to check that the full buffer was being written, and updated cg_read() as well for the interface to be consistent. Will send out once the discussion on patch 1 in v3 reaches a consensus. > > int cg_find_unified_root(char *root, size_t len) > -- > 2.35.1.1178.g4f1659d476-goog >