mirror of
https://github.com/jart/cosmopolitan.git
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Make futexes cancellable by pthreads
This commit is contained in:
Justine Tunney
parent
2278327eba
commit
022536cab6
101 changed files with 627 additions and 391 deletions
116
third_party/nsync/futex.c
vendored
116
third_party/nsync/futex.c
vendored
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@ -23,17 +23,20 @@
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#include "libc/calls/state.internal.h"
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#include "libc/calls/struct/timespec.h"
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#include "libc/calls/struct/timespec.internal.h"
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#include "libc/calls/syscall_support-nt.internal.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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#include "libc/intrin/atomic.h"
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#include "libc/intrin/describeflags.internal.h"
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#include "libc/intrin/strace.internal.h"
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#include "libc/intrin/weaken.h"
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#include "libc/limits.h"
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#include "libc/nt/runtime.h"
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#include "libc/nt/synchronization.h"
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#include "libc/sysv/consts/clock.h"
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#include "libc/sysv/consts/futex.h"
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#include "libc/sysv/consts/timer.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/thread/freebsd.internal.h"
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#include "libc/thread/thread.h"
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#include "libc/thread/tls.h"
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@ -45,7 +48,9 @@
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#define FUTEX_WAIT_BITS_ FUTEX_BITSET_MATCH_ANY
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int _futex (atomic_int *, int, int, const struct timespec *, int *, int);
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errno_t _futex (atomic_int *, int, int, const struct timespec *, int *, int);
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errno_t _futex_wake (atomic_int *, int, int) asm ("_futex");
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int sys_futex_cp (atomic_int *, int, int, const struct timespec *, int *, int);
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static int FUTEX_WAIT_;
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static int FUTEX_PRIVATE_FLAG_;
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@ -59,6 +64,7 @@ __attribute__((__constructor__)) static void nsync_futex_init_ (void) {
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if (IsWindows ()) {
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FUTEX_IS_SUPPORTED = true;
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FUTEX_TIMEOUT_IS_ABSOLUTE = true;
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return;
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}
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@ -70,8 +76,6 @@ __attribute__((__constructor__)) static void nsync_futex_init_ (void) {
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}
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if (!(FUTEX_IS_SUPPORTED = IsLinux () || IsOpenbsd ())) {
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// we're using sched_yield() so let's
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// avoid needless clock_gettime calls
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FUTEX_TIMEOUT_IS_ABSOLUTE = true;
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return;
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}
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@ -101,7 +105,7 @@ __attribute__((__constructor__)) static void nsync_futex_init_ (void) {
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FUTEX_TIMEOUT_IS_ABSOLUTE = true;
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} else if (IsOpenbsd () ||
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(!IsTiny () && IsLinux () &&
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!_futex (&x, FUTEX_WAKE_PRIVATE, 1, 0, 0, 0))) {
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!_futex_wake (&x, FUTEX_WAKE_PRIVATE, 1))) {
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FUTEX_WAIT_ = FUTEX_WAIT;
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FUTEX_PRIVATE_FLAG_ = FUTEX_PRIVATE_FLAG;
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} else {
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@ -110,13 +114,10 @@ __attribute__((__constructor__)) static void nsync_futex_init_ (void) {
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}
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static int nsync_futex_polyfill_ (atomic_int *w, int expect, struct timespec *timeout) {
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int rc;
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int64_t nanos, maxnanos;
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struct timespec ts, deadline;
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if (atomic_load_explicit (w, memory_order_relaxed) != expect) {
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return -EAGAIN;
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}
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ts = nsync_time_now ();
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if (!timeout) {
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deadline = nsync_time_no_deadline;
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@ -129,15 +130,15 @@ static int nsync_futex_polyfill_ (atomic_int *w, int expect, struct timespec *ti
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nanos = 100;
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maxnanos = __SIG_POLLING_INTERVAL_MS * 1000L * 1000;
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while (nsync_time_cmp (deadline, ts) > 0) {
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if (atomic_load_explicit (w, memory_order_relaxed) != expect) {
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return 0;
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}
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ts = nsync_time_add (ts, _timespec_fromnanos (nanos));
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if (nsync_time_cmp (ts, deadline) > 0) {
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ts = deadline;
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}
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if (nsync_time_sleep_until (ts)) {
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return -EINTR;
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if (atomic_load_explicit (w, memory_order_acquire) != expect) {
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return 0;
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}
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if ((rc = nsync_time_sleep_until (ts))) {
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return -rc;
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}
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if (nanos < maxnanos) {
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nanos <<= 1;
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@ -150,10 +151,46 @@ static int nsync_futex_polyfill_ (atomic_int *w, int expect, struct timespec *ti
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return -ETIMEDOUT;
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}
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int nsync_futex_wait_ (atomic_int *w, int expect, char pshare, struct timespec *timeout) {
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static int nsync_futex_wait_win32_ (atomic_int *w, int expect, char pshare, struct timespec *timeout) {
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int rc;
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uint32_t ms;
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struct timespec deadline, interval, remain, wait, now;
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if (timeout) {
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deadline = *timeout;
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} else {
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deadline = nsync_time_no_deadline;
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}
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while (!(rc = _check_interrupts (false, 0))) {
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now = nsync_time_now ();
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if (nsync_time_cmp (now, deadline) > 0) {
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rc = etimedout();
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break;
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}
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remain = nsync_time_sub (deadline, now);
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interval = _timespec_frommillis (__SIG_POLLING_INTERVAL_MS);
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wait = nsync_time_cmp (remain, interval) > 0 ? interval : remain;
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if (atomic_load_explicit (w, memory_order_acquire) != expect) {
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break;
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}
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if (WaitOnAddress (w, &expect, sizeof(int), _timespec_tomillis (wait))) {
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break;
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} else {
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ASSERT (GetLastError () == ETIMEDOUT);
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}
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}
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return rc;
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}
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int nsync_futex_wait_ (atomic_int *w, int expect, char pshare, struct timespec *timeout) {
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int e, rc, op, fop;
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if (atomic_load_explicit (w, memory_order_acquire) != expect) {
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return -EAGAIN;
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}
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op = FUTEX_WAIT_;
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if (pshare == PTHREAD_PROCESS_PRIVATE) {
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op |= FUTEX_PRIVATE_FLAG_;
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@ -165,37 +202,35 @@ int nsync_futex_wait_ (atomic_int *w, int expect, char pshare, struct timespec *
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DescribeTimespec (0, timeout));
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if (FUTEX_IS_SUPPORTED) {
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e = errno;
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if (IsWindows ()) {
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// Windows 8 futexes don't support multiple processes :(
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if (pshare) {
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goto Polyfill;
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}
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e = errno;
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if (_check_interrupts (false, 0)) {
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rc = -errno;
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errno = e;
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} else {
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if (timeout) {
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ms = _timespec_tomillis (*timeout);
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} else {
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ms = -1;
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}
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if (WaitOnAddress (w, &expect, sizeof(int), ms)) {
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rc = 0;
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} else {
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rc = -GetLastError ();
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}
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}
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if (pshare) goto Polyfill;
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rc = nsync_futex_wait_win32_ (w, expect, pshare, timeout);
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} else if (IsFreebsd ()) {
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rc = sys_umtx_timedwait_uint (
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w, expect, pshare, timeout);
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rc = sys_umtx_timedwait_uint (w, expect, pshare, timeout);
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} else {
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rc = _futex (w, op, expect, timeout, 0,
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FUTEX_WAIT_BITS_);
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rc = sys_futex_cp (w, op, expect, timeout, 0, FUTEX_WAIT_BITS_);
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if (IsOpenbsd() && rc > 0) {
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rc = -rc;
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// OpenBSD futex() returns errors as
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// positive numbers without setting the
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// carry flag. It's an irregular miracle
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// because OpenBSD returns ECANCELED if
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// futex() is interrupted w/ SA_RESTART
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// so we're able to tell it apart from
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// PT_MASKED which causes the wrapper
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// to put ECANCELED into errno.
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if (rc == ECANCELED) {
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rc = EINTR;
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}
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errno = rc;
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rc = -1;
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}
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}
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if (rc == -1) {
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rc = -errno;
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errno = e;
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}
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} else {
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Polyfill:
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__get_tls()->tib_flags |= TIB_FLAG_TIME_CRITICAL;
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@ -214,7 +249,6 @@ int nsync_futex_wait_ (atomic_int *w, int expect, char pshare, struct timespec *
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int nsync_futex_wake_ (atomic_int *w, int count, char pshare) {
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int e, rc, op, fop;
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int wake (atomic_int *, int, int) asm ("_futex");
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ASSERT (count == 1 || count == INT_MAX);
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@ -240,9 +274,9 @@ int nsync_futex_wake_ (atomic_int *w, int count, char pshare) {
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} else {
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fop = UMTX_OP_WAKE_PRIVATE;
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}
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rc = sys_umtx_op (w, fop, count, 0, 0);
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rc = _futex_wake (w, fop, count);
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} else {
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rc = wake (w, op, count);
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rc = _futex_wake (w, op, count);
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}
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} else {
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Polyfill:
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