---
name: "seq_hlist_start_head_rcu"
section: "9"
platform: "linux"
package: "linux-manual-4.9"
version: "4.9.228-1"
release: "Debian 9 (Stretch)"
platforms: ["linux"]
url: "https://new.carta.tech/seq_hlist_start_head_rcu"
---

# seq\_hlist\_start\_head\_rcu(9)

start an iteration of a hlist protected by RCU

## NAME

seq\_hlist\_start\_head\_rcu - start an iteration of a hlist protected by RCU

## SYNOPSIS

**struct hlist\_node \* seq\_hlist\_start\_head\_rcu(struct hlist\_head \*** *head***, loff\_t** *pos***);**

## ARGUMENTS

*head*

the head of the hlist

*pos*

the start position of the sequence

## DESCRIPTION

Called at seq\_file-\>op-\>**start**. Call this function if you want to print a header at the top of the output.

This list-traversal primitive may safely run concurrently with the \_rcu list-mutation primitives such as **hlist\_add\_head\_rcu** as long as the traversal is guarded by **rcu\_read\_lock**.

## COPYRIGHT