diff options
| -rw-r--r-- | src/internal/libc.h | 1 | ||||
| -rw-r--r-- | src/malloc/malloc.c | 5 | ||||
| -rw-r--r-- | src/thread/__lock.c | 4 | ||||
| -rw-r--r-- | src/thread/pthread_create.c | 8 |
4 files changed, 12 insertions, 6 deletions
diff --git a/src/internal/libc.h b/src/internal/libc.h index d47f58e0..619bba86 100644 --- a/src/internal/libc.h +++ b/src/internal/libc.h @@ -21,6 +21,7 @@ struct __libc { char can_do_threads; char threaded; char secure; + volatile signed char need_locks; int threads_minus_1; size_t *auxv; struct tls_module *tls_head; diff --git a/src/malloc/malloc.c b/src/malloc/malloc.c index 2553a62e..a803d4c9 100644 --- a/src/malloc/malloc.c +++ b/src/malloc/malloc.c @@ -26,8 +26,11 @@ int __malloc_replaced; static inline void lock(volatile int *lk) { - if (libc.threaded) + int need_locks = libc.need_locks; + if (need_locks) { while(a_swap(lk, 1)) __wait(lk, lk+1, 1, 1); + if (need_locks < 0) libc.need_locks = 0; + } } static inline void unlock(volatile int *lk) diff --git a/src/thread/__lock.c b/src/thread/__lock.c index 5b9b144e..60eece49 100644 --- a/src/thread/__lock.c +++ b/src/thread/__lock.c @@ -18,9 +18,11 @@ void __lock(volatile int *l) { - if (!libc.threaded) return; + int need_locks = libc.need_locks; + if (!need_locks) return; /* fast path: INT_MIN for the lock, +1 for the congestion */ int current = a_cas(l, 0, INT_MIN + 1); + if (need_locks < 0) libc.need_locks = 0; if (!current) return; /* A first spin loop, for medium congestion. */ for (unsigned i = 0; i < 10; ++i) { diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c index 6a3b0c21..6bdfb44f 100644 --- a/src/thread/pthread_create.c +++ b/src/thread/pthread_create.c @@ -118,8 +118,8 @@ _Noreturn void __pthread_exit(void *result) * until the lock is released, which only happens after SYS_exit * has been called, via the exit futex address pointing at the lock. * This needs to happen after any possible calls to LOCK() that might - * skip locking if libc.threads_minus_1 is zero. */ - libc.threads_minus_1--; + * skip locking if process appears single-threaded. */ + if (!--libc.threads_minus_1) libc.need_locks = -1; self->next->prev = self->prev; self->prev->next = self->next; self->prev = self->next = self; @@ -339,7 +339,7 @@ int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict att ~(1UL<<((SIGCANCEL-1)%(8*sizeof(long)))); __tl_lock(); - libc.threads_minus_1++; + if (!libc.threads_minus_1++) libc.need_locks = 1; ret = __clone((c11 ? start_c11 : start), stack, flags, args, &new->tid, TP_ADJ(new), &__thread_list_lock); /* All clone failures translate to EAGAIN. If explicit scheduling @@ -363,7 +363,7 @@ int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict att new->next->prev = new; new->prev->next = new; } else { - libc.threads_minus_1--; + if (!--libc.threads_minus_1) libc.need_locks = 0; } __tl_unlock(); __restore_sigs(&set); |