cgroup_root_from_opts() checks whether (!opts->subsys_mask &&
!opts->none) and returns NULL if so. After that, if allocation fails,
returns ERR_PTR(-ENOMEM). The caller, cgroup_mount(), doesn't treat
NULL as an error but set opts.new_root to NULL; however, later on,
cgroup_set_super() fails with -EINVAL if new_root is NULL.
This is one bizarre error handling sequence especially when all other
opts sanity checks including the very close (!opts->subsys_mask &&
!opts->name) check are done in parse_cgroupfs_options().
Let's move the one-off check in cgroup_root_from_opts() to
parse_cgroupfs_options() where it can be combined with the
(!opts->subsys_mask && !opts->name) check. cgroup_root_from_opts() is
updated to return NULL on memory allocation failure.
Signed-off-by: Tejun Heo <t...@kernel.org>
---
kernel/cgroup.c | 19 ++++++-------------
1 file changed, 6 insertions(+), 13 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index b0e030f..5c8fe40 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1265,10 +1265,10 @@ static int parse_cgroupfs_options(char *data, struct
cgroup_sb_opts *opts)
return -EINVAL;
/*
- * We either have to specify by name or by subsystems. (So all
- * empty hierarchies must have a name).
+ * We either have to specify by name or by subsystems. All empty
+ * hierarchies must have a name and also "none" option specified.
*/
- if (!opts->subsys_mask && !opts->name)
+ if (!opts->subsys_mask && (!opts->name || !opts->none))
return -EINVAL;
return 0;
@@ -1417,12 +1417,9 @@ static struct cgroupfs_root
*cgroup_root_from_opts(struct cgroup_sb_opts *opts)
{
struct cgroupfs_root *root;
- if (!opts->subsys_mask && !opts->none)
- return NULL;
-
root = kzalloc(sizeof(*root), GFP_KERNEL);
if (!root)
- return ERR_PTR(-ENOMEM);
+ return NULL;
init_cgroup_root(root);
@@ -1461,10 +1458,6 @@ static int cgroup_set_super(struct super_block *sb, void
*data)
int ret;
struct cgroup_sb_opts *opts = data;
- /* If we don't have a new root, we can't set up a new sb */
- if (!opts->new_root)
- return -EINVAL;
-
BUG_ON(!opts->subsys_mask && !opts->none);
ret = set_anon_super(sb, NULL);
@@ -1532,8 +1525,8 @@ static struct dentry *cgroup_mount(struct
file_system_type *fs_type,
* reusing an existing hierarchy.
*/
new_root = cgroup_root_from_opts(&opts);
- if (IS_ERR(new_root)) {
- ret = PTR_ERR(new_root);
+ if (!new_root) {
+ ret = -ENOMEM;
goto out_err;
}
opts.new_root = new_root;
--
1.8.5.3
--
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