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make thread list lock a recursive lock 

this is a prerequisite for factoring the membarrier fallback code into
a function that can be called from a context with the thread list
already locked or independently.
This commit is contained in:
Rich Felker 2019-02-22 02:29:21 -05:00
parent 609dd57c4e
commit 7865d569de
1 changed files with 21 additions and 11 deletions
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32
src/thread/pthread_create.c
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@ -17,28 +17,38 @@ weak_alias(dummy_0, __do_orphaned_stdio_locks);
weak_alias(dummy_0, __dl_thread_cleanup);
weak_alias(dummy_0, __dl_prepare_for_threads);
static int tl_lock_count;
static int tl_lock_waiters;
void __tl_lock(void)
{
if (!a_cas(&__thread_list_lock, 0, 1)) return;
do {
a_cas(&__thread_list_lock, 1, 2);
__futexwait(&__thread_list_lock, 2, 0);
} while (a_cas(&__thread_list_lock, 0, 2));
int tid = __pthread_self()->tid;
int val = __thread_list_lock;
if (val == tid) {
tl_lock_count++;
return;
}
while ((val = a_cas(&__thread_list_lock, 0, tid)))
__wait(&__thread_list_lock, &tl_lock_waiters, val, 0);
}
void __tl_unlock(void)
{
if (a_swap(&__thread_list_lock, 0)==2)
__wake(&__thread_list_lock, 1, 0);
if (tl_lock_count) {
tl_lock_count--;
return;
}
a_store(&__thread_list_lock, 0);
if (tl_lock_waiters) __wake(&__thread_list_lock, 1, 0);
}
void __tl_sync(pthread_t td)
{
a_barrier();
if (!__thread_list_lock) return;
a_cas(&__thread_list_lock, 1, 2);
__wait(&__thread_list_lock, 0, 2, 0);
__wake(&__thread_list_lock, 1, 0);
int val = __thread_list_lock;
if (!val) return;
__wait(&__thread_list_lock, &tl_lock_waiters, val, 0);
if (tl_lock_waiters) __wake(&__thread_list_lock, 1, 0);
}
_Noreturn void __pthread_exit(void *result)