selftests: cgroup: return -errno from cg_read()/cg_write() on failure

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>

diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c
index dbaa7aa..e6f3679 100644 (file)
--- 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)