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Diffstat (limited to 'sysdeps/unix/sysv/linux/futex-internal.h')
| -rw-r--r-- | sysdeps/unix/sysv/linux/futex-internal.h | 251 |
1 files changed, 251 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/futex-internal.h b/sysdeps/unix/sysv/linux/futex-internal.h new file mode 100644 index 0000000000..aca0911252 --- /dev/null +++ b/sysdeps/unix/sysv/linux/futex-internal.h @@ -0,0 +1,251 @@ +/* futex operations for glibc-internal use. Linux version. + Copyright (C) 2014-2015 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 + <http://www.gnu.org/licenses/>. */ + +#ifndef FUTEX_INTERNAL_H +#define FUTEX_INTERNAL_H + +#include <sysdeps/nptl/futex-internal.h> +#include <errno.h> +#include <lowlevellock-futex.h> +#include <nptl/pthreadP.h> + +/* See sysdeps/nptl/futex-internal.h for documentation; this file only + contains Linux-specific comments. + + The Linux kernel treats provides absolute timeouts based on the + CLOCK_REALTIME clock and relative timeouts measured against the + CLOCK_MONOTONIC clock. + + We expect a Linux kernel version of 2.6.22 or more recent (since this + version, EINTR is not returned on spurious wake-ups anymore). */ + +/* FUTEX_SHARED is always supported by the Linux kernel. */ +static __always_inline int +futex_supports_pshared (int pshared) +{ + if (__glibc_likely (pshared == PTHREAD_PROCESS_PRIVATE)) + return 0; + else if (pshared == PTHREAD_PROCESS_SHARED) + return 0; + else + return EINVAL; +} + +/* The Linux kernel supports relative timeouts measured against the + CLOCK_MONOTONIC clock. */ +static __always_inline bool +futex_supports_exact_relative_timeouts (void) +{ + return true; +} + +/* See sysdeps/nptl/futex-internal.h for details. */ +static __always_inline int +futex_wait (unsigned int *futex_word, unsigned int expected, int private) +{ + int err = lll_futex_timed_wait (futex_word, expected, NULL, private); + switch (err) + { + case 0: + case -EAGAIN: + case -EINTR: + return -err; + + case -ETIMEDOUT: /* Cannot have happened as we provided no timeout. */ + case -EFAULT: /* Must have been caused by a glibc or application bug. */ + case -EINVAL: /* Either due to wrong alignment or due to the timeout not + being normalized. Must have been caused by a glibc or + application bug. */ + case -ENOSYS: /* Must have been caused by a glibc bug. */ + /* No other errors are documented at this time. */ + default: + futex_fatal_error (); + } +} + +/* See sysdeps/nptl/futex-internal.h for details. */ +static __always_inline int +futex_wait_cancelable (unsigned int *futex_word, unsigned int expected, + int private) +{ + int oldtype; + oldtype = __pthread_enable_asynccancel (); + int err = lll_futex_timed_wait (futex_word, expected, NULL, private); + __pthread_disable_asynccancel (oldtype); + switch (err) + { + case 0: + case -EAGAIN: + case -EINTR: + return -err; + + case -ETIMEDOUT: /* Cannot have happened as we provided no timeout. */ + case -EFAULT: /* Must have been caused by a glibc or application bug. */ + case -EINVAL: /* Either due to wrong alignment or due to the timeout not + being normalized. Must have been caused by a glibc or + application bug. */ + case -ENOSYS: /* Must have been caused by a glibc bug. */ + /* No other errors are documented at this time. */ + default: + futex_fatal_error (); + } +} + +/* See sysdeps/nptl/futex-internal.h for details. */ +static __always_inline int +futex_reltimed_wait (unsigned int *futex_word, unsigned int expected, + const struct timespec *reltime, int private) +{ + int err = lll_futex_timed_wait (futex_word, expected, reltime, private); + switch (err) + { + case 0: + case -EAGAIN: + case -EINTR: + case -ETIMEDOUT: + return -err; + + case -EFAULT: /* Must have been caused by a glibc or application bug. */ + case -EINVAL: /* Either due to wrong alignment or due to the timeout not + being normalized. Must have been caused by a glibc or + application bug. */ + case -ENOSYS: /* Must have been caused by a glibc bug. */ + /* No other errors are documented at this time. */ + default: + futex_fatal_error (); + } +} + +/* See sysdeps/nptl/futex-internal.h for details. */ +static __always_inline int +futex_reltimed_wait_cancelable (unsigned int *futex_word, + unsigned int expected, + const struct timespec *reltime, int private) +{ + int oldtype; + oldtype = __pthread_enable_asynccancel (); + int err = lll_futex_timed_wait (futex_word, expected, reltime, private); + __pthread_disable_asynccancel (oldtype); + switch (err) + { + case 0: + case -EAGAIN: + case -EINTR: + case -ETIMEDOUT: + return -err; + + case -EFAULT: /* Must have been caused by a glibc or application bug. */ + case -EINVAL: /* Either due to wrong alignment or due to the timeout not + being normalized. Must have been caused by a glibc or + application bug. */ + case -ENOSYS: /* Must have been caused by a glibc bug. */ + /* No other errors are documented at this time. */ + default: + futex_fatal_error (); + } +} + +/* See sysdeps/nptl/futex-internal.h for details. */ +static __always_inline int +futex_abstimed_wait (unsigned int *futex_word, unsigned int expected, + const struct timespec *abstime, int private) +{ + /* Work around the fact that the kernel rejects negative timeout values + despite them being valid. */ + if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0))) + return ETIMEDOUT; + int err = lll_futex_timed_wait_bitset (futex_word, expected, abstime, + FUTEX_CLOCK_REALTIME, private); + switch (err) + { + case 0: + case -EAGAIN: + case -EINTR: + case -ETIMEDOUT: + return -err; + + case -EFAULT: /* Must have been caused by a glibc or application bug. */ + case -EINVAL: /* Either due to wrong alignment or due to the timeout not + being normalized. Must have been caused by a glibc or + application bug. */ + case -ENOSYS: /* Must have been caused by a glibc bug. */ + /* No other errors are documented at this time. */ + default: + futex_fatal_error (); + } +} + +/* See sysdeps/nptl/futex-internal.h for details. */ +static __always_inline int +futex_abstimed_wait_cancelable (unsigned int *futex_word, + unsigned int expected, + const struct timespec *abstime, int private) +{ + /* Work around the fact that the kernel rejects negative timeout values + despite them being valid. */ + if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0))) + return ETIMEDOUT; + int oldtype; + oldtype = __pthread_enable_asynccancel (); + int err = lll_futex_timed_wait_bitset (futex_word, expected, abstime, + FUTEX_CLOCK_REALTIME, private); + __pthread_disable_asynccancel (oldtype); + switch (err) + { + case 0: + case -EAGAIN: + case -EINTR: + case -ETIMEDOUT: + return -err; + + case -EFAULT: /* Must have been caused by a glibc or application bug. */ + case -EINVAL: /* Either due to wrong alignment or due to the timeout not + being normalized. Must have been caused by a glibc or + application bug. */ + case -ENOSYS: /* Must have been caused by a glibc bug. */ + /* No other errors are documented at this time. */ + default: + futex_fatal_error (); + } +} + +/* See sysdeps/nptl/futex-internal.h for details. */ +static __always_inline void +futex_wake (unsigned int *futex_word, int processes_to_wake, int private) +{ + int res = lll_futex_wake (futex_word, processes_to_wake, private); + /* No error. Ignore the number of woken processes. */ + if (res >= 0) + return; + switch (res) + { + case -EFAULT: /* Could have happened due to memory reuse. */ + case -EINVAL: /* Could be either due to incorrect alignment (a bug in + glibc or in the application) or due to memory being + reused for a PI futex. We cannot distinguish between the + two causes, and one of them is correct use, so we do not + act in this case. */ + return; + case -ENOSYS: /* Must have been caused by a glibc bug. */ + /* No other errors are documented at this time. */ + default: + futex_fatal_error (); + } +} + +#endif /* futex-internal.h */ |