diff options
| -rw-r--r-- | drivers/tty/pty.c | 9 | ||||
| -rw-r--r-- | fs/devpts/inode.c | 20 | ||||
| -rw-r--r-- | include/linux/devpts_fs.h | 4 |
3 files changed, 30 insertions, 3 deletions
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c index 3b5cde833ee5..2348fa613707 100644 --- a/drivers/tty/pty.c +++ b/drivers/tty/pty.c @@ -688,7 +688,7 @@ static void pty_unix98_shutdown(struct tty_struct *tty) else ptmx_inode = tty->link->driver_data; devpts_kill_index(ptmx_inode, tty->index); - iput(ptmx_inode); /* drop reference we acquired at ptmx_open */ + devpts_del_ref(ptmx_inode); } static const struct tty_operations ptm_unix98_ops = { @@ -785,9 +785,12 @@ static int ptmx_open(struct inode *inode, struct file *filp) * still have /dev/tty opened pointing to the master/slave pair (ptmx * is closed/released before /dev/tty), we must make sure that the inode * is still valid when we call the final pty_unix98_shutdown, thus we - * hold an additional reference to the ptmx inode + * hold an additional reference to the ptmx inode. For the same /dev/tty + * last close case, we also need to make sure the super_block isn't + * destroyed (devpts instance unmounted), before /dev/tty is closed and + * on its release devpts_kill_index is called. */ - ihold(inode); + devpts_add_ref(inode); tty_add_file(tty, filp); diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index 1f107fd51328..655f21f99160 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -575,6 +575,26 @@ void devpts_kill_index(struct inode *ptmx_inode, int idx) mutex_unlock(&allocated_ptys_lock); } +/* + * pty code needs to hold extra references in case of last /dev/tty close + */ + +void devpts_add_ref(struct inode *ptmx_inode) +{ + struct super_block *sb = pts_sb_from_inode(ptmx_inode); + + atomic_inc(&sb->s_active); + ihold(ptmx_inode); +} + +void devpts_del_ref(struct inode *ptmx_inode) +{ + struct super_block *sb = pts_sb_from_inode(ptmx_inode); + + iput(ptmx_inode); + deactivate_super(sb); +} + /** * devpts_pty_new -- create a new inode in /dev/pts/ * @ptmx_inode: inode of the master diff --git a/include/linux/devpts_fs.h b/include/linux/devpts_fs.h index 251a2090a554..e0ee0b3000b2 100644 --- a/include/linux/devpts_fs.h +++ b/include/linux/devpts_fs.h @@ -19,6 +19,8 @@ int devpts_new_index(struct inode *ptmx_inode); void devpts_kill_index(struct inode *ptmx_inode, int idx); +void devpts_add_ref(struct inode *ptmx_inode); +void devpts_del_ref(struct inode *ptmx_inode); /* mknod in devpts */ struct inode *devpts_pty_new(struct inode *ptmx_inode, dev_t device, int index, void *priv); @@ -32,6 +34,8 @@ void devpts_pty_kill(struct inode *inode); /* Dummy stubs in the no-pty case */ static inline int devpts_new_index(struct inode *ptmx_inode) { return -EINVAL; } static inline void devpts_kill_index(struct inode *ptmx_inode, int idx) { } +static inline void devpts_add_ref(struct inode *ptmx_inode) { } +static inline void devpts_del_ref(struct inode *ptmx_inode) { } static inline struct inode *devpts_pty_new(struct inode *ptmx_inode, dev_t device, int index, void *priv) { |