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>

1 files changed, 0 insertions, 5 deletions

diff --git a/arch/alpha/kernel/srm_env.c b/arch/alpha/kernel/srm_env.c
index 78ad7cd1bbd6..d12af472e1c0 100644
--- a/arch/alpha/kernel/srm_env.c
+++ b/arch/alpha/kernel/srm_env.c
@@ -218,7 +218,6 @@ srm_env_init(void)
                                 BASE_DIR);
                 goto cleanup;
         }
-        base_dir->owner = THIS_MODULE;
 
         /*
          * Create per-name subdirectory
@@ -229,7 +228,6 @@ srm_env_init(void)
                                 BASE_DIR, NAMED_DIR);
                 goto cleanup;
         }
-        named_dir->owner = THIS_MODULE;
 
         /*
          * Create per-number subdirectory
@@ -241,7 +239,6 @@ srm_env_init(void)
                 goto cleanup;
 
         }
-        numbered_dir->owner = THIS_MODULE;
 
         /*
          * Create all named nodes
@@ -254,7 +251,6 @@ srm_env_init(void)
                         goto cleanup;
 
                 entry->proc_entry->data         = (void *) entry;
-                entry->proc_entry->owner        = THIS_MODULE;
                 entry->proc_entry->read_proc    = srm_env_read;
                 entry->proc_entry->write_proc   = srm_env_write;
 
@@ -275,7 +271,6 @@ srm_env_init(void)
 
                 entry->id                       = var_num;
                 entry->proc_entry->data         = (void *) entry;
-                entry->proc_entry->owner        = THIS_MODULE;
                 entry->proc_entry->read_proc    = srm_env_read;
                 entry->proc_entry->write_proc   = srm_env_write;
         }