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 78ad7cd1bbd..d12af472e1c 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;
 	}