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>
diff --git a/fs/reiserfs/procfs.c b/fs/reiserfs/procfs.c
index d506640..9229e55 100644
--- a/fs/reiserfs/procfs.c
+++ b/fs/reiserfs/procfs.c
@@ -492,7 +492,6 @@
spin_lock_init(&__PINFO(sb).lock);
REISERFS_SB(sb)->procdir = proc_mkdir(b, proc_info_root);
if (REISERFS_SB(sb)->procdir) {
- REISERFS_SB(sb)->procdir->owner = THIS_MODULE;
REISERFS_SB(sb)->procdir->data = sb;
add_file(sb, "version", show_version);
add_file(sb, "super", show_super);
@@ -556,9 +555,7 @@
{
if (proc_info_root == NULL) {
proc_info_root = proc_mkdir(proc_info_root_name, NULL);
- if (proc_info_root) {
- proc_info_root->owner = THIS_MODULE;
- } else {
+ if (!proc_info_root) {
reiserfs_warning(NULL, "cannot create /proc/%s",
proc_info_root_name);
return 1;