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.
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¶
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/.
