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Linux 2.6 - man page for restart_syscall (linux section 2)

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

COLOPHON
       This page is part of release 3.55 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)
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