Serge E. Hallyn [EMAIL PROTECTED] wrote:
| Quoting [EMAIL PROTECTED] ([EMAIL PROTECTED]):
| >
| > From: Sukadev Bhattiprolu <[EMAIL PROTECTED]>
| > Subject: [PATCH 4/7]: Implement get_pts_ns() and put_pts_ns()
| >
| > Implement get_pts_ns() and put_pts_ns() interfaces.
| >
| > Signed-off-by: Sukadev Bhattiprolu <[EMAIL PROTECTED]>
| > ---
| > include/linux/devpts_fs.h | 21 ++++++++++++++++++++-
| > 1 file changed, 20 insertions(+), 1 deletion(-)
| >
| > Index: 2.6.25-rc5-mm1/include/linux/devpts_fs.h
| > ===================================================================
| > --- 2.6.25-rc5-mm1.orig/include/linux/devpts_fs.h 2008-03-24
20:04:31.000000000 -0700
| > +++ 2.6.25-rc5-mm1/include/linux/devpts_fs.h 2008-03-24
20:05:05.000000000 -0700
| > @@ -27,13 +27,26 @@ struct pts_namespace {
| > extern struct pts_namespace init_pts_ns;
| >
| > #ifdef CONFIG_UNIX98_PTYS
| > -
| > int devpts_new_index(void);
| > void devpts_kill_index(int idx);
| > int devpts_pty_new(struct tty_struct *tty); /* mknod in devpts */
| > struct tty_struct *devpts_get_tty(int number); /* get tty structure */
| > void devpts_pty_kill(int number); /* unlink */
| >
| > +static inline void free_pts_ns(struct kref *ns_kref) { }
| > +
| > +static inline struct pts_namespace *get_pts_ns(struct pts_namespace *ns)
| > +{
| > + if (ns && (ns != &init_pts_ns))
| > + kref_get(&ns->kref);
| > + return ns;
| > +}
| > +static inline void put_pts_ns(struct pts_namespace *ns)
| > +{
| > + if (ns && (ns != &init_pts_ns))
| > + kref_put(&ns->kref, free_pts_ns);
|
| This isn't right, or I'm not thinking right. Don't you somewhere
| need to
|
| 1. rcu_assign ns->mnt->mnt_sb->s_fs_info to NULL
| 2. wait a grace period
| 3. call free_pts_ns and check the refcount on the ns again?
|
| and then do pts_ns_from_inode() under an rcu_read_lock and grab
| a ref to the ns?
Yes, we need the rcu to grab the reference to pts_ns.
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