proc: delete redundant subset=pid check

Two checks in lookup and readdir code should be enough to not have third
check in open code.

Can't open what can't be looked up?

Link: https://lkml.kernel.org/r/YFYYwIBIkytqnkxP@localhost.localdomain
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Alexey Gladkov <gladkov.alexey@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/inode.c

@@ -483,7 +483,6 @@ proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr,
 
 static int proc_reg_open(struct inode *inode, struct file *file)
 {
-	struct proc_fs_info *fs_info = proc_sb_info(inode->i_sb);
 	struct proc_dir_entry *pde = PDE(inode);
 	int rv = 0;
 	typeof_member(struct proc_ops, proc_open) open;
@@ -497,9 +496,6 @@ static int proc_reg_open(struct inode *inode, struct file *file)
 		return rv;
 	}
 
-	if (fs_info->pidonly == PROC_PIDONLY_ON)
-		return -ENOENT;
-
 	/*
 	 * Ensure that
 	 * 1) PDE's ->release hook will be called no matter what