From 99b76233803beab302123d243eea9e41149804f3 Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Wed, 25 Mar 2009 22:48:06 +0300 Subject: proc 2/2: remove struct proc_dir_entry::owner Setting ->owner as done currently (pde->owner = THIS_MODULE) is racy as correctly noted at bug #12454. Someone can lookup entry with NULL ->owner, thus not pinning enything, and release it later resulting in module refcount underflow. We can keep ->owner and supply it at registration time like ->proc_fops and ->data. But this leaves ->owner as easy-manipulative field (just one C assignment) and somebody will forget to unpin previous/pin current module when switching ->owner. ->proc_fops is declared as "const" which should give some thoughts. ->read_proc/->write_proc were just fixed to not require ->owner for protection. rmmod'ed directories will be empty and return "." and ".." -- no harm. And directories with tricky enough readdir and lookup shouldn't be modular. We definitely don't want such modular code. Removing ->owner will also make PDE smaller. So, let's nuke it. Kudos to Jeff Layton for reminding about this, let's say, oversight. http://bugzilla.kernel.org/show_bug.cgi?id=12454 Signed-off-by: Alexey Dobriyan --- fs/proc/inode.c | 19 +++---------------- fs/proc/proc_tty.c | 1 - 2 files changed, 3 insertions(+), 17 deletions(-) (limited to 'fs/proc') diff --git a/fs/proc/inode.c b/fs/proc/inode.c index e11dc22c651..d78ade30554 100644 --- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -58,11 +58,8 @@ static void proc_delete_inode(struct inode *inode) /* Let go of any associated proc directory entry */ de = PROC_I(inode)->pde; - if (de) { - if (de->owner) - module_put(de->owner); + if (de) de_put(de); - } if (PROC_I(inode)->sysctl) sysctl_head_put(PROC_I(inode)->sysctl); clear_inode(inode); @@ -449,12 +446,9 @@ struct inode *proc_get_inode(struct super_block *sb, unsigned int ino, { struct inode * inode; - if (!try_module_get(de->owner)) - goto out_mod; - inode = iget_locked(sb, ino); if (!inode) - goto out_ino; + return NULL; if (inode->i_state & I_NEW) { inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; PROC_I(inode)->fd = 0; @@ -485,16 +479,9 @@ struct inode *proc_get_inode(struct super_block *sb, unsigned int ino, } } unlock_new_inode(inode); - } else { - module_put(de->owner); + } else de_put(de); - } return inode; - -out_ino: - module_put(de->owner); -out_mod: - return NULL; } int proc_fill_super(struct super_block *s) diff --git a/fs/proc/proc_tty.c b/fs/proc/proc_tty.c index d153946d6d1..4a9e0f65ae6 100644 --- a/fs/proc/proc_tty.c +++ b/fs/proc/proc_tty.c @@ -152,7 +152,6 @@ void proc_tty_register_driver(struct tty_driver *driver) if (!ent) return; ent->read_proc = driver->ops->read_proc; - ent->owner = driver->owner; ent->data = driver; driver->proc_entry = ent; -- cgit v1.2.3