glibc/sysdeps/unix/sysv/linux/pselect32.c
Adhemerval Zanella 91cf411ad3 linux: Only use 64-bit syscall if required for pselect
For !__ASSUME_TIME64_SYSCALLS there is no need to issue a 64-bit syscall
if the provided timeout fits in a 32-bit one.  The 64-bit usage should
be rare since the timeout is a relative one.  This also avoids the need
to use supports_time64() (which breaks the usage case of live migration
like CRIU or similar).

Checked on i686-linux-gnu on a 4.15 kernel and on a 5.11 kernel
(with and without --enable-kernel=5.1) and on x86_64-linux-gnu.

Reviewed-by: Lukasz Majewski <lukma@denx.de>
2021-06-22 12:09:52 -03:00

42 lines
1.4 KiB
C

/* Synchronous I/O multiplexing. Linux 32-bit time fallback.
Copyright (C) 2020-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <sys/select.h>
#include <sysdep-cancel.h>
#ifndef __ASSUME_TIME64_SYSCALLS
int
__pselect32 (int nfds, fd_set *readfds, fd_set *writefds,
fd_set *exceptfds, const struct __timespec64 *timeout,
const sigset_t *sigmask)
{
struct timespec ts32, *pts32 = NULL;
if (timeout != NULL)
{
ts32 = valid_timespec64_to_timespec (*timeout);
pts32 = &ts32;
}
return SYSCALL_CANCEL (pselect6, nfds, readfds, writefds, exceptfds,
pts32,
((__syscall_ulong_t[]){ (uintptr_t) sigmask,
__NSIG_BYTES }));
}
#endif