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>

2 files changed, 0 insertions, 5 deletions

diff --git a/drivers/scsi/scsi_devinfo.c b/drivers/scsi/scsi_devinfo.c
index 099b545..b134813 100644
--- a/drivers/scsi/scsi_devinfo.c
+++ b/drivers/scsi/scsi_devinfo.c
@@ -596,8 +596,6 @@ int __init scsi_init_devinfo(void)
 		error = -ENOMEM;
 		goto out;
 	}
-
-	p->owner = THIS_MODULE;
 #endif /* CONFIG_SCSI_PROC_FS */
 
  out:
diff --git a/drivers/scsi/scsi_proc.c b/drivers/scsi/scsi_proc.c
index 82f7b2d..77fbddb 100644
--- a/drivers/scsi/scsi_proc.c
+++ b/drivers/scsi/scsi_proc.c
@@ -115,8 +115,6 @@ void scsi_proc_hostdir_add(struct scsi_host_template *sht)
         	if (!sht->proc_dir)
 			printk(KERN_ERR "%s: proc_mkdir failed for %s\n",
 			       __func__, sht->proc_name);
-		else
-			sht->proc_dir->owner = sht->module;
 	}
 	mutex_unlock(&global_host_template_mutex);
 }
@@ -163,7 +161,6 @@ void scsi_proc_host_add(struct Scsi_Host *shost)
 	} 
 
 	p->write_proc = proc_scsi_write_proc;
-	p->owner = sht->module;
 }
 
 /**