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author | Alexey Dobriyan <adobriyan@gmail.com> | 2009-03-25 22:48:06 +0300 |
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committer | Alexey Dobriyan <adobriyan@gmail.com> | 2009-03-31 01:14:44 +0400 |
commit | 99b76233803beab302123d243eea9e41149804f3 (patch) | |
tree | 398178210fe66845ccd6fa4258ba762a87e023ad /fs/proc | |
parent | 3dec7f59c370c7b58184d63293c3dc984d475840 (diff) | |
download | linux-3.10-99b76233803beab302123d243eea9e41149804f3.tar.gz linux-3.10-99b76233803beab302123d243eea9e41149804f3.tar.bz2 linux-3.10-99b76233803beab302123d243eea9e41149804f3.zip |
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 <adobriyan@gmail.com>
Diffstat (limited to 'fs/proc')
-rw-r--r-- | fs/proc/inode.c | 19 | ||||
-rw-r--r-- | fs/proc/proc_tty.c | 1 |
2 files changed, 3 insertions, 17 deletions
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; |