From: Yosry Ahmed <yosryahmed@google.com>
To: Roman Gushchin <roman.gushchin@linux.dev>
Cc: "Johannes Weiner" <hannes@cmpxchg.org>,
"Michal Hocko" <mhocko@kernel.org>,
"Shakeel Butt" <shakeelb@google.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"David Rientjes" <rientjes@google.com>,
"Tejun Heo" <tj@kernel.org>, "Zefan Li" <lizefan.x@bytedance.com>,
"Jonathan Corbet" <corbet@lwn.net>,
"Shuah Khan" <shuah@kernel.org>, "Yu Zhao" <yuzhao@google.com>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Wei Xu" <weixugc@google.com>, "Greg Thelen" <gthelen@google.com>,
"Chen Wandun" <chenwandun@huawei.com>,
"Vaibhav Jain" <vaibhav@linux.ibm.com>,
"Michal Koutný" <mkoutny@suse.com>,
"Tim Chen" <tim.c.chen@linux.intel.com>,
cgroups@vger.kernel.org, linux-doc@vger.kernel.org,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v3 2/4] selftests: cgroup: return the errno of write() in cg_write() on failure
Date: Fri, 8 Apr 2022 23:43:23 -0700 [thread overview]
Message-ID: <CAJD7tkbiLQ8XV89yKDzJ467A7+=xvRMPw3pYwt+0gSnbwqBtVA@mail.gmail.com> (raw)
In-Reply-To: <YlDlCRSyR9xNW5dJ@carbon.dhcp.thefacebook.com>
On Fri, Apr 8, 2022 at 6:44 PM Roman Gushchin <roman.gushchin@linux.dev> wrote:
>
> On Fri, Apr 08, 2022 at 06:21:55PM -0700, Yosry Ahmed wrote:
> > On Thu, Apr 7, 2022 at 9:57 PM Yosry Ahmed <yosryahmed@google.com> 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 <yosryahmed@google.com>
> > > ---
> > > 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 <roman.gushchin@linux.dev>
> for the whole series. It looks really nice and ready for merging upstream to me.
>
> Thanks!
Thanks a lot for reviewing it! I would appreciate it if you still took
a look at the v4 version of this patch when I send it (probably early
next week) as it's significantly different and includes changes to
cg_read() and read_text() as well.
next prev parent reply other threads:[~2022-04-09 6:44 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-08 4:57 [PATCH v3 0/4] memcg: introduce per-memcg proactive reclaim Yosry Ahmed
2022-04-08 4:57 ` [PATCH v3 1/4] memcg: introduce per-memcg reclaim interface Yosry Ahmed
2022-04-08 13:43 ` Dan Schatzberg
2022-04-08 14:11 ` Michal Hocko
2022-04-08 14:55 ` Dan Schatzberg
2022-04-08 20:08 ` Yosry Ahmed
2022-04-14 17:25 ` Yosry Ahmed
2022-04-20 12:47 ` Michal Hocko
2022-04-11 7:20 ` Michal Hocko
2022-04-08 17:21 ` Yosry Ahmed
2022-04-09 1:13 ` Roman Gushchin
2022-04-08 4:57 ` [PATCH v3 2/4] selftests: cgroup: return the errno of write() in cg_write() on failure Yosry Ahmed
2022-04-09 1:21 ` Yosry Ahmed
2022-04-09 1:44 ` Roman Gushchin
2022-04-09 6:43 ` Yosry Ahmed [this message]
2022-04-09 1:33 ` Roman Gushchin
2022-04-08 4:57 ` [PATCH v3 3/4] selftests: cgroup: fix alloc_anon_noexit() instantly freeing memory Yosry Ahmed
2022-04-09 1:31 ` Roman Gushchin
2022-04-08 4:57 ` [PATCH v3 4/4] selftests: cgroup: add a selftest for memory.reclaim Yosry Ahmed
2022-04-09 1:31 ` Roman Gushchin
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