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From: Roman Gushchin To: Yosry Ahmed Cc: Johannes Weiner , Michal Hocko , Shakeel Butt , Andrew Morton , David Rientjes , Tejun Heo , Zefan Li , Jonathan Corbet , Shuah Khan , Yu Zhao , Dave Hansen , Wei Xu , Greg Thelen , Chen Wandun , Vaibhav Jain , Michal =?iso-8859-1?Q?Koutn=FD?= , Tim Chen , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, Linux Kernel Mailing List , Linux-MM , linux-kselftest@vger.kernel.org Subject: Re: [PATCH v3 2/4] selftests: cgroup: return the errno of write() in cg_write() on failure Message-ID: References: <20220408045743.1432968-1-yosryahmed@google.com> <20220408045743.1432968-3-yosryahmed@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev X-Stat-Signature: 97jyiwq9c9kguuktiyf1f4y9m7pymyer Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Vixq1q2y; spf=pass (imf09.hostedemail.com: domain of roman.gushchin@linux.dev designates 188.165.223.204 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev; dmarc=pass (policy=none) header.from=linux.dev X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: C6904140003 X-HE-Tag: 1649468690-897221 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Apr 08, 2022 at 06:21:55PM -0700, Yosry Ahmed wrote: > 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. Ok, sounds good, please feel free to add my Acked-by: Roman Gushchin for the whole series. It looks really nice and ready for merging upstream to me. Thanks!