Changes in uspace/lib/c/generic/fibril.c [3b1cc8d:e768aea] in mainline

File:

• uspace/lib/c/generic/fibril.c (modified) (10 diffs)

uspace/lib/c/generic/fibril.c

@@ -49 +49 @@
 #include <async.h>
 
-#ifdef FUTEX_UPGRADABLE
-#include <rcu.h>
-#endif
+#include "private/fibril.h"
+
 
 /**
@@ -72 +71 @@
 static void fibril_main(void)
 {
-        /* fibril_futex is locked when a fibril is first started. */
-        futex_unlock(&fibril_futex);
-
-        fibril_t *fibril = __tcb_get()->fibril_data;
-
-#ifdef FUTEX_UPGRADABLE
-        rcu_register_fibril();
-#endif
+        /* fibril_futex and async_futex are locked when a fibril is started. */
+        futex_unlock(&fibril_futex);
+        futex_unlock(&async_futex);
+
+        fibril_t *fibril = fibril_self();
 
         /* Call the implementing function. */
         fibril->retval = fibril->func(fibril->arg);
 
-        futex_down(&async_futex);
+        futex_lock(&async_futex);
         fibril_switch(FIBRIL_FROM_DEAD);
         /* Not reached */
@@ -98 +94 @@
                 return NULL;
 
-        fibril_t *fibril = malloc(sizeof(fibril_t));
+        fibril_t *fibril = calloc(1, sizeof(fibril_t));
         if (!fibril) {
                 tls_free(tcb);
@@ -106 +102 @@
         tcb->fibril_data = fibril;
         fibril->tcb = tcb;
-
-        fibril->func = NULL;
-        fibril->arg = NULL;
-        fibril->stack = NULL;
-        fibril->clean_after_me = NULL;
-        fibril->retval = 0;
-        fibril->flags = 0;
-
-        fibril->waits_for = NULL;
 
         /*
@@ -141 +128 @@
 /** Switch from the current fibril.
  *
- * If stype is FIBRIL_TO_MANAGER or FIBRIL_FROM_DEAD, the async_futex must
- * be held.
+ * The async_futex must be held when entering this function,
+ * and is still held on return.
  *
  * @param stype Switch type. One of FIBRIL_PREEMPT, FIBRIL_TO_MANAGER,
@@ -154 +141 @@
 int fibril_switch(fibril_switch_type_t stype)
 {
+        /* Make sure the async_futex is held. */
+        futex_assert_is_locked(&async_futex);
+
         futex_lock(&fibril_futex);
 
-        fibril_t *srcf = __tcb_get()->fibril_data;
+        fibril_t *srcf = fibril_self();
         fibril_t *dstf = NULL;
 
         /* Choose a new fibril to run */
-        switch (stype) {
-        case FIBRIL_TO_MANAGER:
-        case FIBRIL_FROM_DEAD:
-                /* Make sure the async_futex is held. */
-                assert((atomic_signed_t) async_futex.val.count <= 0);
+        if (list_empty(&ready_list)) {
+                if (stype == FIBRIL_PREEMPT || stype == FIBRIL_FROM_MANAGER) {
+                        // FIXME: This means that as long as there is a fibril
+                        // that only yields, IPC messages are never retrieved.
+                        futex_unlock(&fibril_futex);
+                        return 0;
+                }
 
                 /* If we are going to manager and none exists, create it */
@@ -175 +167 @@
                 dstf = list_get_instance(list_first(&manager_list),
                     fibril_t, link);
-
-                if (stype == FIBRIL_FROM_DEAD)
-                        dstf->clean_after_me = srcf;
-                break;
-        case FIBRIL_PREEMPT:
-        case FIBRIL_FROM_MANAGER:
-                if (list_empty(&ready_list)) {
-                        futex_unlock(&fibril_futex);
-                        return 0;
-                }
-
+        } else {
                 dstf = list_get_instance(list_first(&ready_list), fibril_t,
                     link);
-                break;
-        }
+        }
+
         list_remove(&dstf->link);
+        if (stype == FIBRIL_FROM_DEAD)
+                dstf->clean_after_me = srcf;
 
         /* Put the current fibril into the correct run list */
@@ -201 +185 @@
                 break;
         case FIBRIL_FROM_DEAD:
+        case FIBRIL_FROM_BLOCKED:
                 // Nothing.
                 break;
-        case FIBRIL_TO_MANAGER:
-                /*
-                 * Don't put the current fibril into any list, it should
-                 * already be somewhere, or it will be lost.
-                 */
-                break;
-        }
-
-#ifdef FUTEX_UPGRADABLE
-        if (stype == FIBRIL_FROM_DEAD) {
-                rcu_deregister_fibril();
-        }
-#endif
+        }
+
+        /* Bookkeeping. */
+        futex_give_to(&fibril_futex, dstf);
+        futex_give_to(&async_futex, dstf);
 
         /* Swap to the next fibril. */
@@ -345 +322 @@
 }
 
+fibril_t *fibril_self(void)
+{
+        return __tcb_get()->fibril_data;
+}
+
 /** Return fibril id of the currently running fibril.
  *
@@ -352 +334 @@
 fid_t fibril_get_id(void)
 {
-        return (fid_t) __tcb_get()->fibril_data;
+        return (fid_t) fibril_self();
+}
+
+void fibril_yield(void)
+{
+        futex_lock(&async_futex);
+        (void) fibril_switch(FIBRIL_PREEMPT);
+        futex_unlock(&async_futex);
 }