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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 <adobriyan@gmail.com>
This commit is contained in:
Alexey Dobriyan
2009-03-25 22:48:06 +03:00
parent 3dec7f59c3
commit 99b7623380
55 changed files with 26 additions and 232 deletions
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5
arch/alpha/kernel/srm_env.c
View File

@@ -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;
}