перезапустить системный вызов после прерывания сигналом остановки (restart a system call after interruption by a stop signal)
Имя (Name)
restart_syscall - restart a system call after interruption by a
stop signal
Синопсис (Synopsis)
long restart_syscall(void);
Note: There is no glibc wrapper for this system call; see NOTES.
Описание (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
deduct the already elapsed time when the process continued
execution.
Возвращаемое значение (Return value)
The return value of restart_syscall() is the return value of
whatever system call is being restarted.
Ошибки (Error)
errno is set as per the errors for whatever system call is being
restarted by restart_syscall().
Версии (Versions)
The restart_syscall() system call is present since Linux 2.6.
Стандарты (Conforming to)
This system call is Linux-specific.
Примечание (Note)
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.
The kernel uses restart_syscall() to ensure that when a system
call is restarted after a process has been stopped by a signal
and then resumed by SIGCONT, then the time that the process spent
in the stopped state is counted against the timeout interval
specified in the original system call. In the case of system
calls that take a timeout argument and automatically restart
after a stop signal plus SIGCONT, but which do not have the
restart_syscall() mechanism built in, then, after the process
resumes execution, the time that the process spent in the stop
state is not counted against the timeout value. Notable examples
of system calls that suffer this problem are ppoll(2), select(2),
and pselect(2).
From user space, the operation of restart_syscall() 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.
Смотри также (See also)
sigaction(2), sigreturn(2), signal(7)
