centos man page for restart_syscall

RESTART_SYSCALL(2)					     Linux Programmer's Manual						RESTART_SYSCALL(2)

NAME
       restart_syscall - restart a system call after interruption by a stop signal

SYNOPSIS
       int restart_syscall(void);

       Note: There is no glibc wrapper for this system call; see NOTES.

DESCRIPTION
       The  restart_syscall()  system  call is used to restart certain system calls after a process that was stopped by a signal (e.g., SIGSTOP or
       SIGTSTP) is later resumed after receiving a SIGCONT signal.  This system call is designed only for internal use by the kernel.

       restart_syscall() is used for restarting only those system calls that, when restarted, should adjust their time-related	parameters--namely
       poll(2)	(since	Linux  2.6.24), nanosleep(2) (since Linux 2.6), clock_nanosleep(2) (since Linux 2.6), and futex(2), when employed with the
       FUTEX_WAIT (since Linux 2.6.22) and FUTEX_WAIT_BITSET (since Linux 2.6.31) operations.  restart_syscall() restarts the  interrupted  system
       call  with a time argument that is suitably adjusted to account for the time that has already elapsed (including the time where the process
       was stopped by a signal).  Without the restart_syscall() mechanism, restarting these system calls would not correctly  deduce  the  already
       elapsed time when the process continued execution.

RETURN VALUE
       The return value of restart_syscall() is the return value of whatever system call is being restarted.

ERRORS
       errno is set as per the errors for whatever system call is being restarted by restart_syscall().

VERSIONS
       The restart_syscall() system call is present since Linux 2.6.

CONFORMING TO
       This system call is Linux specific.

NOTES
       There  is  no  glibc wrapper for this system call, because it is intended for use only by the kernel and should never be called by applica-
       tions.

       From user space, the operation of restart_syscall(2) is largely invisible: to the process that made the system call that is  restarted,	it
       appears as though that system call executed and returned in the usual fashion.

SEE ALSO
       sigreturn(2), sigaction(2), signal(7)

COLOPHON
       This  page is part of release 3.53 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/.

Linux								    2013-07-30							RESTART_SYSCALL(2)