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https://github.com/jart/cosmopolitan.git
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98c5847727
This change fixes a bug where nsync waiter objects would leak. It'd mean that long-running programs like runitd would run out of file descriptors on NetBSD where waiter objects have ksem file descriptors. On other OSes this bug is mostly harmless since the worst that can happen with a futex is to leak a little bit of ram. The bug was caused because tib_nsync was sneaking back in after the finalization code had cleared it. This change refactors the thread exiting code to handle nsync teardown appropriately and in making this change I found another issue, which is that user code which is buggy, and tries to exit without joining joinable threads which haven't been detached, would result in a deadlock. That doesn't sound so bad, except the main thread is a joinable thread. So this deadlock would be triggered in ways that put libc at fault. So we now auto-join threads and libc will log a warning to --strace when that happens for any thread
51 lines
2.7 KiB
C
51 lines
2.7 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/calls.h"
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#include "libc/calls/state.internal.h"
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#include "libc/calls/syscall-sysv.internal.h"
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#include "libc/dce.h"
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#include "libc/intrin/atomic.h"
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#include "libc/intrin/likely.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/thread/tls.h"
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/**
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* Returns current thread id.
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*
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* On Linux, and Linux only, this is guaranteed to be equal to getpid()
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* if this is the main thread. On NetBSD, gettid() for the main thread
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* is always 1.
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*
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* @return thread id greater than zero or -1 w/ errno
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* @asyncsignalsafe
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* @vforksafe
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*/
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int gettid(void) {
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int tid;
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if (VERY_LIKELY(__tls_enabled && !__vforked)) {
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tid = atomic_load_explicit(&__get_tls()->tib_ptid, memory_order_relaxed);
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if (VERY_LIKELY(tid > 0))
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return tid;
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}
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if (IsXnuSilicon()) {
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return enosys(); // can only happen if we can't access thread local storage
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} else {
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return sys_gettid();
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}
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}
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