407d933052
fix up clone signature to match the actual behavior. the new __syncall_wait function allows a __synccall callback to wait for other threads to continue without returning, so that it can resume action after the caller finishes. this interface could be made significantly more general/powerful with minimal effort, but i'll wait to do that until it's actually useful for something.
117 lines
2.3 KiB
C
117 lines
2.3 KiB
C
#include "pthread_impl.h"
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#include <semaphore.h>
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static struct chain {
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struct chain *next;
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sem_t sem, sem2;
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} *head, *cur;
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static void (*callback)(void *), *context;
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static int chainlen;
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static sem_t chainlock, chaindone;
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static pthread_rwlock_t lock = PTHREAD_RWLOCK_INITIALIZER;
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static void handler(int sig, siginfo_t *si, void *ctx)
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{
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struct chain ch;
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pthread_t self = __pthread_self();
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int old_errno = errno;
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if (chainlen == libc.threads_minus_1) return;
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sigqueue(self->pid, SIGSYNCCALL, (union sigval){0});
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/* Threads which have already decremented themselves from the
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* thread count must not act. Block further receipt of signals
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* and return. */
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if (self->dead) {
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memset(&((ucontext_t *)ctx)->uc_sigmask, -1, 8);
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errno = old_errno;
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return;
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}
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sem_init(&ch.sem, 0, 0);
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sem_init(&ch.sem2, 0, 0);
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while (sem_wait(&chainlock));
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ch.next = head;
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head = &ch;
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if (++chainlen == libc.threads_minus_1) sem_post(&chaindone);
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sem_post(&chainlock);
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while (sem_wait(&ch.sem));
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callback(context);
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sem_post(&ch.sem2);
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while (sem_wait(&ch.sem));
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errno = old_errno;
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}
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void __synccall_wait()
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{
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struct chain *ch = cur;
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sem_post(&ch->sem2);
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while (sem_wait(&ch->sem));
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sem_post(&ch->sem);
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}
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void __synccall(void (*func)(void *), void *ctx)
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{
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pthread_t self;
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struct sigaction sa;
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struct chain *next;
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uint64_t oldmask;
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if (!libc.threads_minus_1) {
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func(ctx);
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return;
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}
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pthread_rwlock_wrlock(&lock);
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__syscall(SYS_rt_sigprocmask, SIG_BLOCK, (uint64_t[]){-1}, &oldmask, 8);
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sem_init(&chaindone, 0, 0);
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sem_init(&chainlock, 0, 1);
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chainlen = 0;
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callback = func;
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context = ctx;
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sa.sa_flags = SA_SIGINFO | SA_RESTART;
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sa.sa_sigaction = handler;
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sigfillset(&sa.sa_mask);
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__libc_sigaction(SIGSYNCCALL, &sa, 0);
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self = __pthread_self();
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sigqueue(self->pid, SIGSYNCCALL, (union sigval){0});
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while (sem_wait(&chaindone));
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for (cur=head; cur; cur=cur->next) {
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sem_post(&cur->sem);
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while (sem_wait(&cur->sem2));
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}
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func(ctx);
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for (cur=head; cur; cur=next) {
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next = cur->next;
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sem_post(&cur->sem);
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}
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sa.sa_flags = 0;
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sa.sa_handler = SIG_IGN;
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__libc_sigaction(SIGSYNCCALL, &sa, 0);
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__syscall(SYS_rt_sigprocmask, SIG_SETMASK, &oldmask, 0, 8);
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pthread_rwlock_unlock(&lock);
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}
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void __synccall_lock()
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{
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pthread_rwlock_rdlock(&lock);
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}
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void __synccall_unlock()
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{
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pthread_rwlock_unlock(&lock);
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}
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