GET_ROBUST_LIST(2)                                     Linux System Calls                                     GET_ROBUST_LIST(2)



NAME
       get_robust_list, set_robust_list - get/set the 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);

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 only notified about the location of the head of the list.

       get_robust_list returns the head of the robust futex list of the thread with TID defined by the pid argument. If  pid  is
       0,  the  returned head belongs to the current thread.  head_ptr is the pointer to the head of the list of robust futexes.
       The get_robust_list function stores the address of the head of the list here.  len_ptr is the pointer to the length vari-
       able.  get_robust_list stores sizeof(**head_ptr) here.

       set_robust_list  sets  the  head  of  the list of robust futexes owned by the current thread to head.  len is the size of
       *head.


RETURN VALUE
       The set_robust_list and get_robust_list functions return zero when the operation is successful, an error code otherwise.


ERRORS
       The set_robust_list function fails  with  EINVAL  if  the  len  value  does  not  match  the  size  of  structure  struct
       robust_list_head expected by kernel.

       The  get_robust_list  function  fails  with EPERM if the current process does not have permission to see the robust futex
       list of the thread with the TID pid, ESRCH if a thread with the TID pid does not exist, or EFAULT  if  the  head  of  the
       robust futex list can't be stored in the space specified by the head argument.


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

       The system call is only available for debugging purposes and is not needed for normal operations.

       Both system calls are not available to application programs as functions; they can be called using the  syscall(3)  func-
       tion.


SEE ALSO
       futex(2), pthread_mutexattr_setrobust_np(3)



Linux                                                     8 August 2006                                       GET_ROBUST_LIST(2)