selftests: cgroup: fix unsigned comparison with less than zero

[ Upstream commit 333d073dee3a6865171d43e3b0a9ff688bff5891 ]

'size' is unsigned, it never less than zero.

Link: https://lkml.kernel.org/r/20221105110611.28920-1-yuehaibing@huawei.com
Fixes: 6c26df84e1f2 ("selftests: cgroup: return -errno from cg_read()/cg_write() on failure")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: zefan li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c
index 4c52cc6..e8bbbdb 100644 (file)
--- a/tools/testing/selftests/cgroup/cgroup_util.c
+++ b/tools/testing/selftests/cgroup/cgroup_util.c
@@ -555,6 +555,7 @@ int proc_mount_contains(const char *option)
 ssize_t proc_read_text(int pid, bool thread, const char *item, char *buf, size_t size)
 {
        char path[PATH_MAX];
+       ssize_t ret;
 
        if (!pid)
                snprintf(path, sizeof(path), "/proc/%s/%s",
@@ -562,8 +563,8 @@ 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);
 
-       size = read_text(path, buf, size);
-       return size < 0 ? -1 : size;
+       ret = read_text(path, buf, size);
+       return ret < 0 ? -1 : ret;
 }
 
 int proc_read_strstr(int pid, bool thread, const char *item, const char *needle)