Re: [RFC/PATCH 1/8]: CGroup Files: Add locking mode to cgroups control files

["Paul Menage" <menage@google.com>]

On Tue, May 13, 2008 at 2:23 AM, Li Zefan <lizf@cn.fujitsu.com> wrote:
>  > +
>  > +/**
>  > + * cgroup_file_lock(). Helper for cgroup read/write methods.
>  > + * @cgrp:  the cgroup being acted on
>  > + * @cft:   the control file being written to or read from
>  > + * *write: true if the access is a write access.
>
>  s/*write/@write
>

Fixed.

>  > @@ -1518,16 +1580,21 @@ static ssize_t cgroup_file_read(struct f
>  >       struct cftype *cft = __d_cft(file->f_dentry);
>  >       struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
>  >
>  > -     if (!cft || cgroup_is_removed(cgrp))
>  > +     if (cgroup_is_removed(cgrp))
>  >               return -ENODEV;
>  >
>
>  This check seems redundant now.
>

It's not needed for safety, but it doesn't seem to hurt to check
cgroup_is_removed() prior to doing any copying, since we'll fail after
copying anyway if cgroup_is_removed() returns true (once we've taken
any relevant locks).

Paul