On Sun, May 20, 2007 at 08:41:02PM -0700, [email protected] wrote:
> Subject: procfs directory entry cleanup
> From: "Changli Gao" <[email protected]>
>
> Function proc_register() will assign proc_dir_operations and
> proc_dir_inode_operations to ent's members proc_fops and proc_iops
> correctly if ent is a directory. So the early assignment isn't
> necessary.
> --- a/fs/proc/generic.c~procfs-directory-entry-cleanup
> +++ a/fs/proc/generic.c
> @@ -649,9 +649,6 @@ struct proc_dir_entry *proc_mkdir_mode(c
>
> ent = proc_create(&parent, name, S_IFDIR | mode, 2);
> if (ent) {
> - ent->proc_fops = &proc_dir_operations;
> - ent->proc_iops = &proc_dir_inode_operations;
> -
> if (proc_register(parent, ent) < 0) {
> kfree(ent);
> ent = NULL;
> @@ -686,10 +683,6 @@ struct proc_dir_entry *create_proc_entry
>
> ent = proc_create(&parent,name,mode,nlink);
> if (ent) {
> - if (S_ISDIR(mode)) {
> - ent->proc_fops = &proc_dir_operations;
> - ent->proc_iops = &proc_dir_inode_operations;
> - }
> if (proc_register(parent, ent) < 0) {
> kfree(ent);
> ent = NULL;
This should add race because new PDE for directory will be glued to tree
with NULL ->proc_iops and, at least, vfs_getattr() doesn't check for
NULL ->i_op.
I've tried to reproduce this scenario with udelay() inserted before
S_ISDIR checks in proc_register() but got some panic while in X,
so no cookie for me. Maybe it's impossible, indeed.
Anyway, this patch + moving ->proc_fops and ->proc_iops initialization
before gluing is OK with me.
-
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