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

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

SYNOPSIS
       int restartsyscall(void);

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

DESCRIPTION
       The restartsyscall() 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  sys‐
       tem call is designed only for internal use by the kernel.

       restartsyscall()  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),
       clocknanosleep(2) (since Linux 2.6), and futex(2), when employed  with
       the  FUTEXWAIT (since Linux 2.6.22) and FUTEXWAITBITSET (since Linux
       2.6.31) operations.  restartsyscall() 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  restartsyscall()  mechanism,
       restarting these system calls would not correctly  deduce  the  already
       elapsed time when the process continued execution.

RETURN VALUE
       The  return  value of restartsyscall() 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 restartsyscall().

VERSIONS
       The restartsyscall() 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 restartsyscall(2) is largely invisi‐
       ble:  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                RESTARTSYSCALL(2)