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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
139 lines
5 KiB
C
139 lines
5 KiB
C
#ifndef COSMOPOLITAN_LIBC_THREAD_POSIXTHREAD_INTERNAL_H_
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#define COSMOPOLITAN_LIBC_THREAD_POSIXTHREAD_INTERNAL_H_
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#include "libc/calls/struct/sched_param.h"
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#include "libc/calls/struct/sigaltstack.h"
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#include "libc/intrin/atomic.h"
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#include "libc/intrin/dll.h"
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#include "libc/runtime/runtime.h"
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#include "libc/thread/pt.internal.h"
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#include "libc/thread/thread.h"
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#include "libc/thread/tls.h"
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#define PT_BLOCKER_EVENT ((atomic_int *)-1)
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COSMOPOLITAN_C_START_
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// LEGAL TRANSITIONS ┌──> TERMINATED ─┐
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// pthread_create ─┬─> JOINABLE ─┴┬─> DETACHED ───┴─> ZOMBIE
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// └──────────────┘
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enum PosixThreadStatus {
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// this is a running thread that needs pthread_join()
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//
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// the following transitions are possible:
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//
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// - kPosixThreadJoinable -> kPosixThreadTerminated if start_routine()
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// returns, or is longjmp'd out of by pthread_exit(), and the thread
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// is waiting to be joined.
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//
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// - kPosixThreadJoinable -> kPosixThreadDetached if pthread_detach()
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// is called on this thread.
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//
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// - kPosixThreadJoinable -> kPosixThreadZombie if another thread
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// calls fork().
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kPosixThreadJoinable,
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// this is a managed thread that'll be cleaned up by the library.
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//
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// the following transitions are possible:
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//
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// - kPosixThreadDetached -> kPosixThreadZombie if start_routine()
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// returns, or is longjmp'd out of by pthread_exit(), and the thread
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// is waiting to be joined.
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//
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// - kPosixThreadDetached -> kPosixThreadZombie if another thread
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// calls fork().
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kPosixThreadDetached,
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// this is a joinable thread that terminated.
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//
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// the following transitions are possible:
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//
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// - kPosixThreadTerminated -> _pthread_free() will happen when
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// pthread_join() is called by the user.
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// - kPosixThreadTerminated -> kPosixThreadZombie will happen when
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// pthread_detach() is called by the user.
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// - kPosixThreadTerminated -> kPosixThreadZombie if another thread
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// calls fork().
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kPosixThreadTerminated,
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// this is a detached thread that terminated.
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//
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// the following transitions are possible:
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//
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// - kPosixThreadZombie -> _pthread_free() will happen whenever
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// convenient, e.g. pthread_create() entry or atexit handler.
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kPosixThreadZombie,
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};
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#define POSIXTHREAD_CONTAINER(e) DLL_CONTAINER(struct PosixThread, list, e)
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typedef struct __locale_struct *locale_t;
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struct PosixThread {
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int pt_flags; // 0x00: see PT_* constants
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atomic_int pt_canceled; // 0x04: thread has bad beliefs
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_Atomic(enum PosixThreadStatus) pt_status;
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_Atomic(atomic_int *) pt_blocker;
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atomic_int pt_refs; // prevents decimation
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void *(*pt_start)(void *); // creation callback
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void *pt_val; // start param / return val
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char *pt_tls; // bottom of tls allocation
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struct CosmoTib *tib; // middle of tls allocation
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struct Dll list; // list of threads
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struct _pthread_cleanup_buffer *pt_cleanup;
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uint64_t pt_blkmask;
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int64_t pt_event;
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locale_t pt_locale;
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intptr_t pt_exiter[5];
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pthread_attr_t pt_attr;
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atomic_bool pt_intoff;
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};
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typedef void (*atfork_f)(void);
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extern struct Dll *_pthread_list;
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extern atomic_uint _pthread_count;
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extern struct PosixThread _pthread_static;
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extern _Atomic(pthread_key_dtor) _pthread_key_dtor[PTHREAD_KEYS_MAX];
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int _pthread_cond_signal(pthread_cond_t *) libcesque paramsnonnull();
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int _pthread_mutex_lock(pthread_mutex_t *) libcesque paramsnonnull();
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int _pthread_mutex_trylock(pthread_mutex_t *) libcesque paramsnonnull();
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int _pthread_mutex_unlock(pthread_mutex_t *) libcesque paramsnonnull();
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int _pthread_mutex_wipe_np(pthread_mutex_t *) libcesque paramsnonnull();
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int _pthread_reschedule(struct PosixThread *) libcesque;
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int _pthread_setschedparam_freebsd(int, int, const struct sched_param *);
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int _pthread_tid(struct PosixThread *) libcesque;
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intptr_t _pthread_syshand(struct PosixThread *) libcesque;
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long _pthread_cancel_ack(void) libcesque;
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void _pthread_decimate(enum PosixThreadStatus) libcesque;
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void _pthread_free(struct PosixThread *) libcesque paramsnonnull();
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void _pthread_lock(void) libcesque;
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void _pthread_onfork_child(void) libcesque;
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void _pthread_onfork_parent(void) libcesque;
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void _pthread_onfork_prepare(void) libcesque;
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void _pthread_unlock(void) libcesque;
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void _pthread_zombify(struct PosixThread *) libcesque;
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int _pthread_cond_wait(pthread_cond_t *, pthread_mutex_t *) libcesque
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paramsnonnull();
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int _pthread_cond_timedwait(pthread_cond_t *, pthread_mutex_t *,
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const struct timespec *) libcesque
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paramsnonnull((1, 2));
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forceinline pureconst struct PosixThread *_pthread_self(void) {
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return (struct PosixThread *)__get_tls()->tib_pthread;
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}
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forceinline void _pthread_ref(struct PosixThread *pt) {
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atomic_fetch_add_explicit(&pt->pt_refs, 1, memory_order_acq_rel);
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}
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forceinline void _pthread_unref(struct PosixThread *pt) {
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atomic_fetch_sub_explicit(&pt->pt_refs, 1, memory_order_acq_rel);
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}
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COSMOPOLITAN_C_END_
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#endif /* COSMOPOLITAN_LIBC_THREAD_POSIXTHREAD_INTERNAL_H_ */
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