In fact, Andrew, please, drop this patch. Fixing yet another race in
proc would be done by suppying PDE's with valid ->proc_fops before
proc_register(), so this patch would be effectively reverted.
> proc-remove-useless-checks-in-proc_register.patch
> Subject: proc: remove useless checks in proc_register()
> From: Alexey Dobriyan <[email protected]>
>
> Before proc_register() all PDEs are created by proc_create() which doesn't set
> ->proc_iops and ->proc_fops -- they're NULL. So those branches in
> proc_register() are always taken.
>
> Signed-off-by: Alexey Dobriyan <[email protected]>
> Signed-off-by: Andrew Morton <[email protected]>
> ---
>
> fs/proc/generic.c | 15 +++++----------
> 1 file changed, 5 insertions(+), 10 deletions(-)
>
> diff -puN fs/proc/generic.c~proc-remove-useless-checks-in-proc_register fs/proc/generic.c
> --- a/fs/proc/generic.c~proc-remove-useless-checks-in-proc_register
> +++ a/fs/proc/generic.c
> @@ -526,19 +526,14 @@ static int proc_register(struct proc_dir
> dp->low_ino = i;
>
> if (S_ISDIR(dp->mode)) {
> - if (dp->proc_iops == NULL) {
> - dp->proc_fops = &proc_dir_operations;
> - dp->proc_iops = &proc_dir_inode_operations;
> - }
> + dp->proc_fops = &proc_dir_operations;
> + dp->proc_iops = &proc_dir_inode_operations;
> dir->nlink++;
> } else if (S_ISLNK(dp->mode)) {
> - if (dp->proc_iops == NULL)
> - dp->proc_iops = &proc_link_inode_operations;
> + dp->proc_iops = &proc_link_inode_operations;
> } else if (S_ISREG(dp->mode)) {
> - if (dp->proc_fops == NULL)
> - dp->proc_fops = &proc_file_operations;
> - if (dp->proc_iops == NULL)
> - dp->proc_iops = &proc_file_inode_operations;
> + dp->proc_fops = &proc_file_operations;
> + dp->proc_iops = &proc_file_inode_operations;
> }
>
> spin_lock(&proc_subdir_lock);