Changes in uspace/lib/c/generic/futex.c [f6372be9:a35b458] in mainline

File:

• uspace/lib/c/generic/futex.c (modified) (2 diffs)

uspace/lib/c/generic/futex.c

@@ -34 +34 @@
 
 #include <futex.h>
-
-#include <assert.h>
 #include <atomic.h>
-#include <fibril.h>
-#include <io/kio.h>
-
-#include "private/fibril.h"
-
-//#define DPRINTF(...) kio_printf(__VA_ARGS__)
-#define DPRINTF(...) ((void)0)
 
 /** Initialize futex counter.
@@ -56 +47 @@
 }
 
-#ifdef CONFIG_DEBUG_FUTEX
 
-void __futex_assert_is_locked(futex_t *futex, const char *name)
+#ifdef FUTEX_UPGRADABLE
+
+int _upgrade_futexes = 0;
+static futex_t upg_and_wait_futex = FUTEX_INITIALIZER;
+
+void futex_upgrade_all_and_wait(void)
 {
-        void *owner = __atomic_load_n(&futex->owner, __ATOMIC_RELAXED);
-        fibril_t *self = (fibril_t *) fibril_get_id();
-        if (owner != self) {
-                DPRINTF("Assertion failed: %s (%p) is not locked by fibril %p (instead locked by fibril %p).\n", name, futex, self, owner);
-        }
-        assert(owner == self);
-}
+        futex_down(&upg_and_wait_futex);
 
-void __futex_assert_is_not_locked(futex_t *futex, const char *name)
-{
-        void *owner = __atomic_load_n(&futex->owner, __ATOMIC_RELAXED);
-        fibril_t *self = (fibril_t *) fibril_get_id();
-        if (owner == self) {
-                DPRINTF("Assertion failed: %s (%p) is already locked by fibril %p.\n", name, futex, self);
-        }
-        assert(owner != self);
-}
-
-void __futex_lock(futex_t *futex, const char *name)
-{
-        /* We use relaxed atomics to avoid violating C11 memory model.
-         * They should compile to regular load/stores, but simple assignments
-         * would be UB by definition.
-         */
-
-        fibril_t *self = (fibril_t *) fibril_get_id();
-        DPRINTF("Locking futex %s (%p) by fibril %p.\n", name, futex, self);
-        __futex_assert_is_not_locked(futex, name);
-        futex_down(futex);
-
-        void *prev_owner = __atomic_exchange_n(&futex->owner, self, __ATOMIC_RELAXED);
-        assert(prev_owner == NULL);
-
-        atomic_inc(&self->futex_locks);
-}
-
-void __futex_unlock(futex_t *futex, const char *name)
-{
-        fibril_t *self = (fibril_t *) fibril_get_id();
-        DPRINTF("Unlocking futex %s (%p) by fibril %p.\n", name, futex, self);
-        __futex_assert_is_locked(futex, name);
-        __atomic_store_n(&futex->owner, NULL, __ATOMIC_RELAXED);
-        atomic_dec(&self->futex_locks);
-        futex_up(futex);
-}
-
-bool __futex_trylock(futex_t *futex, const char *name)
-{
-        fibril_t *self = (fibril_t *) fibril_get_id();
-        bool success = futex_trydown(futex);
-        if (success) {
-                void *owner = __atomic_load_n(&futex->owner, __ATOMIC_RELAXED);
-                assert(owner == NULL);
-
-                __atomic_store_n(&futex->owner, self, __ATOMIC_RELAXED);
-
-                atomic_inc(&self->futex_locks);
-
-                DPRINTF("Trylock on futex %s (%p) by fibril %p succeeded.\n", name, futex, self);
-        } else {
-                DPRINTF("Trylock on futex %s (%p) by fibril %p failed.\n", name, futex, self);
+        if (!_upgrade_futexes) {
+                rcu_assign(_upgrade_futexes, 1);
+                _rcu_synchronize(BM_BLOCK_THREAD);
         }
 
-        return success;
-}
-
-void __futex_give_to(futex_t *futex, void *new_owner, const char *name)
-{
-        fibril_t *self = fibril_self();
-        fibril_t *no = new_owner;
-        DPRINTF("Passing futex %s (%p) from fibril %p to fibril %p.\n", name, futex, self, no);
-
-        __futex_assert_is_locked(futex, name);
-        atomic_dec(&self->futex_locks);
-        atomic_inc(&no->futex_locks);
-        __atomic_store_n(&futex->owner, new_owner, __ATOMIC_RELAXED);
+        futex_up(&upg_and_wait_futex);
 }