1RESTART_SYSCALL(2)         Linux Programmer's Manual        RESTART_SYSCALL(2)
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NAME

6       restart_syscall  -  restart  a system call after interruption by a stop
7       signal
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SYNOPSIS

10       int restart_syscall(void);
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12       Note: There is no glibc wrapper for this system call; see NOTES.
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DESCRIPTION

15       The restart_syscall() system call is used  to  restart  certain  system
16       calls  after  a  process that was stopped by a signal (e.g., SIGSTOP or
17       SIGTSTP) is later resumed after receiving a SIGCONT signal.  This  sys‐
18       tem call is designed only for internal use by the kernel.
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20       restart_syscall()  is used for restarting only those system calls that,
21       when restarted,  should  adjust  their  time-related  parameters—namely
22       poll(2)   (since   Linux   2.6.24),  nanosleep(2)  (since  Linux  2.6),
23       clock_nanosleep(2) (since Linux 2.6), and futex(2), when employed  with
24       the  FUTEX_WAIT (since Linux 2.6.22) and FUTEX_WAIT_BITSET (since Linux
25       2.6.31) operations.  restart_syscall() restarts the interrupted  system
26       call  with a time argument that is suitably adjusted to account for the
27       time that has already elapsed (including the time where the process was
28       stopped   by  a  signal).   Without  the  restart_syscall()  mechanism,
29       restarting these system calls would not correctly  deduce  the  already
30       elapsed time when the process continued execution.
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RETURN VALUE

33       The  return  value of restart_syscall() is the return value of whatever
34       system call is being restarted.
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ERRORS

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

41       The restart_syscall() system call is present since Linux 2.6.
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CONFORMING TO

44       This system call is Linux specific.
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NOTES

47       There  is no glibc wrapper for this system call, because it is intended
48       for use only by the kernel and should never be called by applications.
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50       From user space, the operation of restart_syscall(2) is largely invisi‐
51       ble:  to  the  process  that made the system call that is restarted, it
52       appears as though that system call executed and returned in  the  usual
53       fashion.
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SEE ALSO

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

59       This  page  is  part of release 3.53 of the Linux man-pages project.  A
60       description of the project, and information about reporting  bugs,  can
61       be found at http://www.kernel.org/doc/man-pages/.
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65Linux                             2013-07-30                RESTART_SYSCALL(2)
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