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authorAlexey Dobriyan <adobriyan@gmail.com>2009-03-25 22:48:06 +0300
committerAlexey Dobriyan <adobriyan@gmail.com>2009-03-31 01:14:44 +0400
commit99b76233803beab302123d243eea9e41149804f3 (patch)
tree398178210fe66845ccd6fa4258ba762a87e023ad /fs/proc/inode.c
parent3dec7f59c370c7b58184d63293c3dc984d475840 (diff)
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/inode.c')
-rw-r--r--fs/proc/inode.c19
1 files changed, 3 insertions, 16 deletions
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index e11dc22c6511..d78ade305541 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)