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proc 2/2: remove struct proc_dir_entry::owner

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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 <[email protected]>
This commit is contained in:
Alexey Dobriyan 2009-03-25 22:48:06 +03:00
commit 99b7623380
55 changed files with 26 additions and 232 deletions
Download patch file Download diff file Expand all files Collapse all files

4
net/sunrpc/cache.c
View file

@ -313,7 +313,6 @@ static int create_cache_proc_entries(struct cache_detail *cd)
cd->proc_ent = proc_mkdir(cd->name, proc_net_rpc);
if (cd->proc_ent == NULL)
goto out_nomem;
cd->proc_ent->owner = cd->owner;
cd->channel_ent = cd->content_ent = NULL;
p = proc_create_data("flush", S_IFREG|S_IRUSR|S_IWUSR,
@ -321,7 +320,6 @@ static int create_cache_proc_entries(struct cache_detail *cd)
cd->flush_ent = p;
if (p == NULL)
goto out_nomem;
p->owner = cd->owner;
if (cd->cache_request || cd->cache_parse) {
p = proc_create_data("channel", S_IFREG|S_IRUSR|S_IWUSR,
@ -329,7 +327,6 @@ static int create_cache_proc_entries(struct cache_detail *cd)
cd->channel_ent = p;
if (p == NULL)
goto out_nomem;
p->owner = cd->owner;
}
if (cd->cache_show) {
p = proc_create_data("content", S_IFREG|S_IRUSR|S_IWUSR,
@ -337,7 +334,6 @@ static int create_cache_proc_entries(struct cache_detail *cd)
cd->content_ent = p;
if (p == NULL)
goto out_nomem;
p->owner = cd->owner;
}
return 0;
out_nomem:

10
net/sunrpc/stats.c
View file

@ -262,14 +262,8 @@ void
rpc_proc_init(void)
{
dprintk("RPC: registering /proc/net/rpc\n");
if (!proc_net_rpc) {
struct proc_dir_entry *ent;
ent = proc_mkdir("rpc", init_net.proc_net);
if (ent) {
ent->owner = THIS_MODULE;
proc_net_rpc = ent;
}
}
if (!proc_net_rpc)
proc_net_rpc = proc_mkdir("rpc", init_net.proc_net);
}
void