>>> static int cgroup_set_super(struct super_block *sb, void *data) >>> { >>> int ret; >>> - struct cgroupfs_root *root = data; >>> + 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; >>> + >> I think this should be BUG_ON(). If set_super() is called, >> we are allocating a new root, so opts->new_root won't be NULL. > > Not true - if you try to mount a hierarchy by name, but with no > subsystem options, then we don't construct a new root, but we still > call sget(). If we find a superblock with the right name then we use > it, else sget() will allocate a new superblock and call > cgroup_set_super(), at which point we need to fail. >
Ah, I see. >>> + struct cgroupfs_root *new_root = cgroup_root_from_opts(&opts); >> Why not just declare new_root in the beginning of cgroup_get_sb()? > > Because it's not needed for the entire scope of the function. Keeping > its scope as small as possible makes it clearer what it's being used > for. > If we had been doing this, we'll see many: (no if, while, for) { ... } in kernel code, but I don't remember I ever saw this style. _______________________________________________ Containers mailing list contain...@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list Devel@openvz.org https://openvz.org/mailman/listinfo/devel