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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. 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>
143 lines
5.0 KiB
C
143 lines
5.0 KiB
C
/* futex helper functions for glibc-internal use.
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Copyright (C) 2020-2021 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 <sysdep.h>
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#include <time.h>
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#include <futex-internal.h>
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#include <kernel-features.h>
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#ifndef __ASSUME_TIME64_SYSCALLS
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static int
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__futex_abstimed_wait_common32 (unsigned int* futex_word,
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unsigned int expected, int op,
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const struct __timespec64* abstime,
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int private, bool cancel)
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{
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struct timespec ts32, *pts32 = NULL;
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if (abstime != NULL)
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{
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ts32 = valid_timespec64_to_timespec (*abstime);
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pts32 = &ts32;
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}
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if (cancel)
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return INTERNAL_SYSCALL_CANCEL (futex, futex_word, op, expected,
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pts32, NULL /* Unused. */,
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FUTEX_BITSET_MATCH_ANY);
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else
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return INTERNAL_SYSCALL_CALL (futex, futex_word, op, expected,
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pts32, NULL /* Unused. */,
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FUTEX_BITSET_MATCH_ANY);
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}
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#endif /* ! __ASSUME_TIME64_SYSCALLS */
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static int
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__futex_abstimed_wait_common64 (unsigned int* futex_word,
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unsigned int expected, int op,
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const struct __timespec64* abstime,
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int private, bool cancel)
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{
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if (cancel)
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return INTERNAL_SYSCALL_CANCEL (futex_time64, futex_word, op, expected,
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abstime, NULL /* Unused. */,
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FUTEX_BITSET_MATCH_ANY);
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else
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return INTERNAL_SYSCALL_CALL (futex_time64, futex_word, op, expected,
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abstime, NULL /* Ununsed. */,
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FUTEX_BITSET_MATCH_ANY);
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}
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static int
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__futex_abstimed_wait_common (unsigned int* futex_word,
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unsigned int expected, clockid_t clockid,
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const struct __timespec64* abstime,
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int private, bool cancel)
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{
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int err;
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unsigned int clockbit;
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/* Work around the fact that the kernel rejects negative timeout values
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despite them being valid. */
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if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))
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return ETIMEDOUT;
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if (! lll_futex_supported_clockid (clockid))
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return EINVAL;
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clockbit = (clockid == CLOCK_REALTIME) ? FUTEX_CLOCK_REALTIME : 0;
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int op = __lll_private_flag (FUTEX_WAIT_BITSET | clockbit, private);
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#ifdef __ASSUME_TIME64_SYSCALLS
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err = __futex_abstimed_wait_common64 (futex_word, expected, op, abstime,
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private, cancel);
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#else
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bool need_time64 = abstime != NULL && !in_time_t_range (abstime->tv_sec);
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if (need_time64)
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{
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err = __futex_abstimed_wait_common64 (futex_word, expected, op, abstime,
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private, cancel);
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if (err == -ENOSYS)
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err = -EOVERFLOW;
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}
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else
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err = __futex_abstimed_wait_common32 (futex_word, expected, op, abstime,
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private, cancel);
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#endif
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switch (err)
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{
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case 0:
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case -EAGAIN:
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case -EINTR:
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case -ETIMEDOUT:
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case -EINVAL:
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case -EOVERFLOW: /* Passed absolute timeout uses 64 bit time_t type, but
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underlying kernel does not support 64 bit time_t futex
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syscalls. */
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return -err;
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case -EFAULT: /* Must have been caused by a glibc or application bug. */
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case -ENOSYS: /* Must have been caused by a glibc bug. */
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/* No other errors are documented at this time. */
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default:
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futex_fatal_error ();
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}
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}
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int
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__futex_abstimed_wait64 (unsigned int* futex_word, unsigned int expected,
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clockid_t clockid,
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const struct __timespec64* abstime, int private)
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{
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return __futex_abstimed_wait_common (futex_word, expected, clockid,
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abstime, private, false);
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}
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libc_hidden_def (__futex_abstimed_wait64)
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int
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__futex_abstimed_wait_cancelable64 (unsigned int* futex_word,
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unsigned int expected, clockid_t clockid,
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const struct __timespec64* abstime,
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int private)
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{
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return __futex_abstimed_wait_common (futex_word, expected, clockid,
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abstime, private, true);
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}
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libc_hidden_def (__futex_abstimed_wait_cancelable64)
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