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 applications.

       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 exe‐
       cuted and returned in the usual fashion.

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

COLOPHON
       This page is part of release 3.74 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at http://www.kernel.org/doc/man-pages/.



Linux                                       2014-02-11                         RESTART_SYSCALL(2)