Index: uspace/lib/c/generic/async/client.c =================================================================== --- uspace/lib/c/generic/async/client.c (revision b59318e5ac29b0f8d47f0b4407a9f99be6ad5654) +++ uspace/lib/c/generic/async/client.c (revision ab6edb66478acf791a711b3f91d2a5a370fb7a0c) @@ -372,7 +372,6 @@ /* Leave the async_futex locked when entering this function */ - fibril_switch(FIBRIL_TO_MANAGER); - - /* Futex is up automatically after fibril_switch */ + fibril_switch(FIBRIL_FROM_BLOCKED); + futex_unlock(&async_futex); done: @@ -445,7 +444,6 @@ /* Leave the async_futex locked when entering this function */ - fibril_switch(FIBRIL_TO_MANAGER); - - /* Futex is up automatically after fibril_switch */ + fibril_switch(FIBRIL_FROM_BLOCKED); + futex_unlock(&async_futex); if (!msg->done) @@ -511,7 +509,6 @@ /* Leave the async_futex locked when entering this function */ - fibril_switch(FIBRIL_TO_MANAGER); - - /* Futex is up automatically after fibril_switch() */ + fibril_switch(FIBRIL_FROM_BLOCKED); + futex_unlock(&async_futex); } Index: uspace/lib/c/generic/async/server.c =================================================================== --- uspace/lib/c/generic/async/server.c (revision b59318e5ac29b0f8d47f0b4407a9f99be6ad5654) +++ uspace/lib/c/generic/async/server.c (revision ab6edb66478acf791a711b3f91d2a5a370fb7a0c) @@ -997,11 +997,6 @@ * case, route_call() will perform the wakeup. */ - fibril_switch(FIBRIL_TO_MANAGER); - - /* - * Futex is up after getting back from async_manager. - * Get it again. - */ - futex_lock(&async_futex); + fibril_switch(FIBRIL_FROM_BLOCKED); + if ((usecs) && (conn->wdata.to_event.occurred) && (list_empty(&conn->msg_queue))) { @@ -1143,14 +1138,11 @@ { while (true) { - if (fibril_switch(FIBRIL_FROM_MANAGER)) { - futex_unlock(&async_futex); - /* - * async_futex is always held when entering a manager - * fibril. - */ - continue; - } - futex_lock(&async_futex); + fibril_switch(FIBRIL_FROM_MANAGER); + + /* + * The switch only returns when there is no non-manager fibril + * it can run. + */ suseconds_t timeout; @@ -1226,11 +1218,5 @@ static errno_t async_manager_fibril(void *arg) { - futex_unlock(&async_futex); - - /* - * async_futex is always locked when entering manager - */ async_manager_worker(); - return 0; } Index: uspace/lib/c/generic/fibril.c =================================================================== --- uspace/lib/c/generic/fibril.c (revision b59318e5ac29b0f8d47f0b4407a9f99be6ad5654) +++ uspace/lib/c/generic/fibril.c (revision ab6edb66478acf791a711b3f91d2a5a370fb7a0c) @@ -71,6 +71,7 @@ static void fibril_main(void) { - /* fibril_futex is locked when a fibril is first started. */ - futex_unlock(&fibril_futex); + /* 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(); @@ -127,6 +128,6 @@ /** 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, @@ -140,4 +141,7 @@ 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); @@ -146,9 +150,11 @@ /* Choose a new fibril to run */ - switch (stype) { - case FIBRIL_TO_MANAGER: - case FIBRIL_FROM_DEAD: - /* Make sure the async_futex is held. */ - futex_assert_is_locked(&async_futex); + if (list_empty(&ready_list)) { + if (stype == FIBRIL_PREEMPT) { + // 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 */ @@ -161,25 +167,12 @@ dstf = list_get_instance(list_first(&manager_list), fibril_t, link); - - /* Bookkeeping. */ - futex_give_to(&async_futex, dstf); - - if (stype == FIBRIL_FROM_DEAD) - dstf->clean_after_me = srcf; - break; - case FIBRIL_PREEMPT: - case FIBRIL_FROM_MANAGER: - futex_assert_is_not_locked(&async_futex); - - 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 */ @@ -192,16 +185,12 @@ 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; } /* Bookkeeping. */ futex_give_to(&fibril_futex, dstf); + futex_give_to(&async_futex, dstf); /* Swap to the next fibril. */ @@ -350,5 +339,7 @@ void fibril_yield(void) { - fibril_switch(FIBRIL_PREEMPT); + futex_lock(&async_futex); + (void) fibril_switch(FIBRIL_PREEMPT); + futex_unlock(&async_futex); } Index: uspace/lib/c/generic/fibril_synch.c =================================================================== --- uspace/lib/c/generic/fibril_synch.c (revision b59318e5ac29b0f8d47f0b4407a9f99be6ad5654) +++ uspace/lib/c/generic/fibril_synch.c (revision ab6edb66478acf791a711b3f91d2a5a370fb7a0c) @@ -116,9 +116,9 @@ check_for_deadlock(&fm->oi); f->waits_for = &fm->oi; - fibril_switch(FIBRIL_TO_MANAGER); + fibril_switch(FIBRIL_FROM_BLOCKED); } else { fm->oi.owned_by = f; - futex_unlock(&async_futex); - } + } + futex_unlock(&async_futex); } @@ -206,11 +206,11 @@ check_for_deadlock(&frw->oi); f->waits_for = &frw->oi; - fibril_switch(FIBRIL_TO_MANAGER); + fibril_switch(FIBRIL_FROM_BLOCKED); } else { /* Consider the first reader the owner. */ if (frw->readers++ == 0) frw->oi.owned_by = f; - futex_unlock(&async_futex); - } + } + futex_unlock(&async_futex); } @@ -230,10 +230,10 @@ check_for_deadlock(&frw->oi); f->waits_for = &frw->oi; - fibril_switch(FIBRIL_TO_MANAGER); + fibril_switch(FIBRIL_FROM_BLOCKED); } else { frw->oi.owned_by = f; frw->writers++; - futex_unlock(&async_futex); - } + } + futex_unlock(&async_futex); } @@ -377,8 +377,12 @@ list_append(&wdata.wu_event.link, &fcv->waiters); _fibril_mutex_unlock_unsafe(fm); - fibril_switch(FIBRIL_TO_MANAGER); + fibril_switch(FIBRIL_FROM_BLOCKED); + futex_unlock(&async_futex); + + // XXX: This could be replaced with an unlocked version to get rid + // of the unlock-lock pair. I deliberately don't do that because + // further changes would most likely need to revert that optimization. fibril_mutex_lock(fm); - /* async_futex not held after fibril_switch() */ futex_lock(&async_futex); if (wdata.to_event.inlist) @@ -698,7 +702,7 @@ wdata.fid = fibril_get_id(); list_append(&wdata.wu_event.link, &sem->waiters); - fibril_switch(FIBRIL_TO_MANAGER); - - /* async_futex not held after fibril_switch() */ + + fibril_switch(FIBRIL_FROM_BLOCKED); + futex_unlock(&async_futex); } Index: uspace/lib/c/generic/private/fibril.h =================================================================== --- uspace/lib/c/generic/private/fibril.h (revision b59318e5ac29b0f8d47f0b4407a9f99be6ad5654) +++ uspace/lib/c/generic/private/fibril.h (revision ab6edb66478acf791a711b3f91d2a5a370fb7a0c) @@ -59,5 +59,5 @@ typedef enum { FIBRIL_PREEMPT, - FIBRIL_TO_MANAGER, + FIBRIL_FROM_BLOCKED, FIBRIL_FROM_MANAGER, FIBRIL_FROM_DEAD Index: uspace/lib/c/generic/rcu.c =================================================================== --- uspace/lib/c/generic/rcu.c (revision b59318e5ac29b0f8d47f0b4407a9f99be6ad5654) +++ uspace/lib/c/generic/rcu.c (revision ab6edb66478acf791a711b3f91d2a5a370fb7a0c) @@ -373,5 +373,7 @@ blocked_fib.is_ready = false; futex_unlock(&rcu.sync_lock.futex); - fibril_switch(FIBRIL_TO_MANAGER); + futex_lock(&async_futex); + fibril_switch(FIBRIL_FROM_BLOCKED); + futex_unlock(&async_futex); futex_lock(&rcu.sync_lock.futex); } while (rcu.sync_lock.locked);