From 6c26df84e1f2f9181c0741865105a53537da842c Mon Sep 17 00:00:00 2001
From: Yosry Ahmed <yosryahmed@google.com>
Date: Fri, 29 Apr 2022 14:36:59 -0700
Subject: [PATCH 2/4] selftests: cgroup: return -errno from
cg_read()/cg_write() on failure
Git-commit: 6c26df84e1f2f9181c0741865105a53537da842c
Patch-mainline: v5.19-rc1
References: jsc#PED-808
Currently, cg_read()/cg_write() returns 0 on success and -1 on failure.
Modify them to return the -errno on failure.
Link: https://lkml.kernel.org/r/20220425190040.2475377-3-yosryahmed@google.com
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Chen Wandun <chenwandun@huawei.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Michal Koutn" <mkoutny@suse.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Vaibhav Jain <vaibhav@linux.ibm.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
tools/testing/selftests/cgroup/cgroup_util.c | 44 +++++++++-----------
1 file changed, 19 insertions(+), 25 deletions(-)
diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c
index dbaa7aabbb4a..e6f3679cdcc0 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.c
+++ b/tools/testing/selftests/cgroup/cgroup_util.c
@@ -19,6 +19,7 @@
#include "cgroup_util.h"
#include "../clone3/clone3_selftests.h"
+/* Returns read len on success, or -errno on failure. */
static ssize_t read_text(const char *path, char *buf, size_t max_len)
{
ssize_t len;
@@ -26,35 +27,29 @@ static ssize_t read_text(const char *path, char *buf, size_t max_len)
fd = open(path, O_RDONLY);
if (fd < 0)
- return fd;
+ return -errno;
len = read(fd, buf, max_len - 1);
- if (len < 0)
- goto out;
- buf[len] = 0;
-out:
+ if (len >= 0)
+ buf[len] = 0;
+
close(fd);
- return len;
+ return len < 0 ? -errno : len;
}
+/* Returns written len on success, or -errno on failure. */
static ssize_t write_text(const char *path, char *buf, ssize_t len)
{
int fd;
fd = open(path, O_WRONLY | O_APPEND);
if (fd < 0)
- return fd;
+ return -errno;
len = write(fd, buf, len);
- if (len < 0) {
- close(fd);
- return len;
- }
-
close(fd);
-
- return len;
+ return len < 0 ? -errno : len;
}
char *cg_name(const char *root, const char *name)
@@ -87,16 +82,16 @@ char *cg_control(const char *cgroup, const char *control)
return ret;
}
+/* Returns 0 on success, or -errno on failure. */
int cg_read(const char *cgroup, const char *control, char *buf, size_t len)
{
char path[PATH_MAX];
+ ssize_t ret;
snprintf(path, sizeof(path), "%s/%s", cgroup, control);
- if (read_text(path, buf, len) >= 0)
- return 0;
-
- return -1;
+ ret = read_text(path, buf, len);
+ return ret >= 0 ? 0 : ret;
}
int cg_read_strcmp(const char *cgroup, const char *control,
@@ -177,17 +172,15 @@ long cg_read_lc(const char *cgroup, const char *control)
return cnt;
}
+/* Returns 0 on success, or -errno on failure. */
int cg_write(const char *cgroup, const char *control, char *buf)
{
char path[PATH_MAX];
- ssize_t len = strlen(buf);
+ ssize_t len = strlen(buf), ret;
snprintf(path, sizeof(path), "%s/%s", cgroup, control);
-
- if (write_text(path, buf, len) == len)
- return 0;
-
- return -1;
+ ret = write_text(path, buf, len);
+ return ret == len ? 0 : ret;
}
int cg_find_unified_root(char *root, size_t len)
@@ -545,7 +538,8 @@ ssize_t proc_read_text(int pid, bool thread, const char *item, char *buf, size_t
else
snprintf(path, sizeof(path), "/proc/%d/%s", pid, item);
- return read_text(path, buf, size);
+ size = read_text(path, buf, size);
+ return size < 0 ? -1 : size;
}
int proc_read_strstr(int pid, bool thread, const char *item, const char *needle)
--
2.35.3