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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>
61 lines
1.9 KiB
C
61 lines
1.9 KiB
C
/* Synchronous I/O multiplexing. Linux/microblaze version.
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Copyright (C) 2019-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <signal.h>
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#include <time.h>
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#include <sys/poll.h>
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#include <sysdep-cancel.h>
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#ifndef __ASSUME_PSELECT
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int
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__pselect32 (int nfds, fd_set *readfds, fd_set *writefds,
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fd_set *exceptfds, const struct __timespec64 *timeout,
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const sigset_t *sigmask)
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{
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/* The fallback uses 'select' which shows the race condition regarding
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signal mask set/restore, requires two additional syscalls, and has
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a worse timeout precision (microseconds instead of nanoseconds). */
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struct timeval tv32, *ptv32 = NULL;
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if (timeout != NULL)
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{
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if (! valid_nanoseconds (timeout->tv_nsec))
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{
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__set_errno (EINVAL);
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return -1;
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}
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tv32 = valid_timespec64_to_timeval (*timeout);
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ptv32 = &tv32;
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}
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sigset_t savemask;
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if (sigmask != NULL)
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__sigprocmask (SIG_SETMASK, sigmask, &savemask);
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/* select itself is a cancellation entrypoint. */
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int ret = __select (nfds, readfds, writefds, exceptfds, ptv32);
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if (sigmask != NULL)
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__sigprocmask (SIG_SETMASK, &savemask, NULL);
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return ret;
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}
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#endif /* __ASSUME_PSELECT */
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