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 executed and returned in the usual
       fashion.

SEE ALSO

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

COLOPHON

       This page is part of release 3.54 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)