proc: skip branch in /proc/*/* lookup

Code is structured like this:

	for ( ... p < last; p++) {
		if (memcmp == 0)
			break;
	}
	if (p >= last)
		ERROR
	OK

gcc doesn't see that if if lookup succeeds than post loop branch will
never be taken and skip it.

[[email protected]: proc_pident_instantiate() no longer takes an inode*]
Link: http://lkml.kernel.org/r/20180423213954.GD9043@avx2
Signed-off-by: Alexey Dobriyan <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Cc: Al Viro <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

fs/proc/base.c

@@ -2439,14 +2439,11 @@ static struct dentry *proc_pident_lookup(struct inode *dir,
 	for (p = ents; p < last; p++) {
 		if (p->len != dentry->d_name.len)
 			continue;
-		if (!memcmp(dentry->d_name.name, p->name, p->len))
+		if (!memcmp(dentry->d_name.name, p->name, p->len)) {
+			res = proc_pident_instantiate(dentry, task, p);
 			break;
+		}
 	}
-	if (p >= last)
-		goto out;
-
-	res = proc_pident_instantiate(dentry, task, p);
-out:
 	put_task_struct(task);
 out_no_task:
 	return res;