Linux manual pages Section 2: System Calls  

Name

get_robust_list, set_robust_list — get/set list of robust futexes

Synopsis

#include <linux/futex.h>
#include <syscall.h>
long get_robust_list( int pid,
  struct robust_list_head **head_ptr,
  size_t *len_ptr);
 
long set_robust_list( struct robust_list_head *head,
  size_t len);
 
[Note] Note
There are no glibc wrappers for these system calls; see NOTES.

DESCRIPTION

The robust futex implementation needs to maintain per-thread lists of robust futexes which are unlocked when the thread exits. These lists are managed in user space; the kernel is notified about only the location of the head of the list.

The get_robust_list() system call returns the head of the robust futex list of the thread whose thread ID is specified in pid. If pid is 0, the head of the list for the calling thread is returned. The list head is stored in the location pointed to by head_ptr. The size of the object pointed to by **head_ptr is stored in len_ptr.

The set_robust_list() system call requests the kernel to record the head of the list of robust futexes owned by the calling thread. The head argument is the list head to record. The len argument should be sizeof(*head).

RETURN VALUE

The set_robust_list() and get_robust_list() system calls return zero when the operation is successful, an error code otherwise.

ERRORS

The set_robust_list() system call can fail with the following error:

EINVAL

len does not match the size of structure struct robust_list_head expected by kernel.

The get_robust_list() system call can fail with the following errors:

EPERM

The calling process does not have permission to see the robust futex list of the thread with the thread ID pid, and does not have the CAP_SYS_PTRACE capability.

ESRCH

No thread with the thread ID pid could be found.

EFAULT

The head of the robust futex list can't be stored at the location head.

VERSIONS

These system calls were added in Linux 2.6.17. No library support is provided; use syscall(2).

NOTES

These system calls are not needed by normal applications. No support for them is provided in glibc. In the unlikely event that you want to call them directly, use syscall(2).

A thread can have only one robust futex list; therefore applications that wish to use this functionality should use the robust mutexes provided by glibc.

SEE ALSO

futex(2)

Documentation/robust-futexes.txt and Documentation/robust-futex-ABI.txt in the Linux kernel source tree

COLOPHON

This page is part of release 3.52 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man−pages/.


  Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
Written by Ivana Varekova <varekovaredhat.com>

%%%LICENSE_START(VERBATIM)
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Since the Linux kernel and libraries are constantly changing, this
manual page may be incorrect or out-of-date.  The author(s) assume no
responsibility for errors or omissions, or for damages resulting from
the use of the information contained herein.  The author(s) may not
have taken the same level of care in the production of this manual,
which is licensed free of charge, as they might when working
professionally.

Formatted or processed versions of this manual, if unaccompanied by
the source, must acknowledge the copyright and authors of this work.
%%%LICENSE_END

FIXME Something could be added to this page (or exit(2))
      about exit_robust_list processing