| 1,6 → 1,5 |
|---|
| /* |
| * Copyright (c) 2006 Ondrej Palkovsky |
| * Copyright (c) 2007 Jakub Jermar |
| * Copyright (c) 2009 Jakub Jermar |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| 33,314 → 32,86 |
|---|
| /** @file |
| */ |
| |
| #include <fibril_sync.h> |
| #include <fibril.h> |
| #include <async.h> |
| #include <adt/list.h> |
| #include <fibril.h> |
| #include <thread.h> |
| #include <tls.h> |
| #include <malloc.h> |
| #include <unistd.h> |
| #include <stdio.h> |
| #include <libarch/faddr.h> |
| #include <futex.h> |
| #include <assert.h> |
| #include <async.h> |
| |
| #ifndef FIBRIL_INITIAL_STACK_PAGES_NO |
| #define FIBRIL_INITIAL_STACK_PAGES_NO 1 |
| #endif |
| |
| /** |
| * This futex serializes access to ready_list, serialized_list and manager_list. |
| */ |
| static atomic_t fibril_futex = FUTEX_INITIALIZER; |
| |
| static LIST_INITIALIZE(ready_list); |
| static LIST_INITIALIZE(serialized_list); |
| static LIST_INITIALIZE(manager_list); |
| |
| static void fibril_main(void); |
| |
| /** Number of threads that are executing a manager fibril. */ |
| static int threads_in_manager; |
| /** Number of threads that are executing a manager fibril and are serialized. */ |
| static int serialized_threads; /* Protected by async_futex */ |
| /** Thread-local count of serialization. If > 0, we must not preempt */ |
| static __thread int serialization_count; |
| |
| /** Setup fibril information into TCB structure */ |
| fibril_t *fibril_setup(void) |
| void fibril_mutex_initialize(fibril_mutex_t *fm) |
| { |
| fibril_t *f; |
| tcb_t *tcb; |
| |
| tcb = __make_tls(); |
| if (!tcb) |
| return NULL; |
| |
| f = malloc(sizeof(fibril_t)); |
| if (!f) { |
| __free_tls(tcb); |
| return NULL; |
| } |
| |
| tcb->fibril_data = f; |
| f->tcb = tcb; |
| |
| f->func = NULL; |
| f->arg = NULL; |
| f->stack = NULL; |
| f->clean_after_me = NULL; |
| f->retval = 0; |
| f->flags = 0; |
| |
| return f; |
| fm->counter = 1; |
| list_initialize(&fm->waiters); |
| } |
| |
| void fibril_teardown(fibril_t *f) |
| void fibril_mutex_lock(fibril_mutex_t *fm) |
| { |
| __free_tls(f->tcb); |
| free(f); |
| futex_down(&async_futex); |
| if (fm->counter-- <= 0) { |
| fibril_t *f = (fibril_t *) fibril_get_id(); |
| list_append(&f->link, &fm->waiters); |
| fibril_switch(FIBRIL_TO_MANAGER); |
| } else { |
| futex_up(&async_futex); |
| } |
| } |
| |
| /** Function that spans the whole life-cycle of a fibril. |
| * |
| * Each fibril begins execution in this function. Then the function implementing |
| * the fibril logic is called. After its return, the return value is saved. |
| * The fibril then switches to another fibril, which cleans up after it. |
| */ |
| void fibril_main(void) |
| bool fibril_mutex_trylock(fibril_mutex_t *fm) |
| { |
| fibril_t *f = __tcb_get()->fibril_data; |
| |
| /* Call the implementing function. */ |
| f->retval = f->func(f->arg); |
| |
| fibril_switch(FIBRIL_FROM_DEAD); |
| /* not reached */ |
| } |
| |
| /** Switch from the current fibril. |
| * |
| * If calling with FIBRIL_TO_MANAGER parameter, the async_futex should be |
| * held. |
| * |
| * @param stype Switch type. One of FIBRIL_PREEMPT, FIBRIL_TO_MANAGER, |
| * FIBRIL_FROM_MANAGER, FIBRIL_FROM_DEAD. The parameter |
| * describes the circumstances of the switch. |
| * @return Return 0 if there is no ready fibril, |
| * return 1 otherwise. |
| */ |
| int fibril_switch(fibril_switch_type_t stype) |
| { |
| fibril_t *srcf, *dstf; |
| int retval = 0; |
| bool locked = false; |
| |
| futex_down(&fibril_futex); |
| |
| if (stype == FIBRIL_PREEMPT && list_empty(&ready_list)) |
| goto ret_0; |
| |
| if (stype == FIBRIL_FROM_MANAGER) { |
| if (list_empty(&ready_list) && list_empty(&serialized_list)) |
| goto ret_0; |
| /* |
| * Do not preempt if there is not enough threads to run the |
| * ready fibrils which are not serialized. |
| */ |
| if (list_empty(&serialized_list) && |
| threads_in_manager <= serialized_threads) { |
| goto ret_0; |
| } |
| futex_down(&async_futex); |
| if (fm->counter > 0) { |
| fm->counter--; |
| locked = true; |
| } |
| /* If we are going to manager and none exists, create it */ |
| if (stype == FIBRIL_TO_MANAGER || stype == FIBRIL_FROM_DEAD) { |
| while (list_empty(&manager_list)) { |
| futex_up(&fibril_futex); |
| async_create_manager(); |
| futex_down(&fibril_futex); |
| } |
| } |
| futex_up(&async_futex); |
| |
| srcf = __tcb_get()->fibril_data; |
| if (stype != FIBRIL_FROM_DEAD) { |
| /* Save current state */ |
| if (!context_save(&srcf->ctx)) { |
| if (serialization_count) |
| srcf->flags &= ~FIBRIL_SERIALIZED; |
| if (srcf->clean_after_me) { |
| /* |
| * Cleanup after the dead fibril from which we |
| * restored context here. |
| */ |
| void *stack = srcf->clean_after_me->stack; |
| if (stack) { |
| /* |
| * This check is necessary because a |
| * thread could have exited like a |
| * normal fibril using the |
| * FIBRIL_FROM_DEAD switch type. In that |
| * case, its fibril will not have the |
| * stack member filled. |
| */ |
| free(stack); |
| } |
| fibril_teardown(srcf->clean_after_me); |
| srcf->clean_after_me = NULL; |
| } |
| return 1; /* futex_up already done here */ |
| } |
| |
| /* Save myself to the correct run list */ |
| if (stype == FIBRIL_PREEMPT) |
| list_append(&srcf->link, &ready_list); |
| else if (stype == FIBRIL_FROM_MANAGER) { |
| list_append(&srcf->link, &manager_list); |
| threads_in_manager--; |
| } else { |
| /* |
| * If stype == FIBRIL_TO_MANAGER, don't put ourselves to |
| * any list, we should already be somewhere, or we will |
| * be lost. |
| */ |
| } |
| } |
| |
| /* Choose a new fibril to run */ |
| if (stype == FIBRIL_TO_MANAGER || stype == FIBRIL_FROM_DEAD) { |
| dstf = list_get_instance(manager_list.next, fibril_t, link); |
| if (serialization_count && stype == FIBRIL_TO_MANAGER) { |
| serialized_threads++; |
| srcf->flags |= FIBRIL_SERIALIZED; |
| } |
| threads_in_manager++; |
| |
| if (stype == FIBRIL_FROM_DEAD) |
| dstf->clean_after_me = srcf; |
| } else { |
| if (!list_empty(&serialized_list)) { |
| dstf = list_get_instance(serialized_list.next, fibril_t, |
| link); |
| serialized_threads--; |
| } else { |
| dstf = list_get_instance(ready_list.next, fibril_t, |
| link); |
| } |
| } |
| list_remove(&dstf->link); |
| |
| futex_up(&fibril_futex); |
| context_restore(&dstf->ctx); |
| /* not reached */ |
| |
| ret_0: |
| futex_up(&fibril_futex); |
| return retval; |
| return locked; |
| } |
| |
| /** Create a new fibril. |
| * |
| * @param func Implementing function of the new fibril. |
| * @param arg Argument to pass to func. |
| * |
| * @return Return 0 on failure or TLS of the new fibril. |
| */ |
| fid_t fibril_create(int (*func)(void *), void *arg) |
| void fibril_mutex_unlock(fibril_mutex_t *fm) |
| { |
| fibril_t *f; |
| |
| f = fibril_setup(); |
| if (!f) |
| return 0; |
| f->stack = (char *) malloc(FIBRIL_INITIAL_STACK_PAGES_NO * |
| getpagesize()); |
| if (!f->stack) { |
| fibril_teardown(f); |
| return 0; |
| futex_down(&async_futex); |
| assert(fm->counter <= 0); |
| if (fm->counter++ < 0) { |
| link_t *tmp; |
| fibril_t *f; |
| |
| assert(!list_empty(&fm->waiters)); |
| tmp = fm->waiters.next; |
| f = list_get_instance(tmp, fibril_t, link); |
| list_remove(&f->link); |
| fibril_add_ready((fid_t) f); |
| } |
| |
| f->func = func; |
| f->arg = arg; |
| |
| context_save(&f->ctx); |
| context_set(&f->ctx, FADDR(fibril_main), f->stack, |
| FIBRIL_INITIAL_STACK_PAGES_NO * getpagesize(), f->tcb); |
| |
| return (fid_t) f; |
| futex_up(&async_futex); |
| } |
| |
| /** Add a fibril to the ready list. |
| * |
| * @param fid Pointer to the fibril structure of the fibril to be |
| * added. |
| */ |
| void fibril_add_ready(fid_t fid) |
| void fibril_rwlock_initialize(fibril_rwlock_t *frw) |
| { |
| fibril_t *f; |
| |
| f = (fibril_t *) fid; |
| futex_down(&fibril_futex); |
| if ((f->flags & FIBRIL_SERIALIZED)) |
| list_append(&f->link, &serialized_list); |
| else |
| list_append(&f->link, &ready_list); |
| futex_up(&fibril_futex); |
| fibril_mutex_initialize(&frw->fm); |
| } |
| |
| /** Add a fibril to the manager list. |
| * |
| * @param fid Pointer to the fibril structure of the fibril to be |
| * added. |
| */ |
| void fibril_add_manager(fid_t fid) |
| void fibril_rwlock_read_lock(fibril_rwlock_t *frw) |
| { |
| fibril_t *f; |
| |
| f = (fibril_t *) fid; |
| |
| futex_down(&fibril_futex); |
| list_append(&f->link, &manager_list); |
| futex_up(&fibril_futex); |
| fibril_mutex_lock(&frw->fm); |
| } |
| |
| /** Remove one manager from the manager list. */ |
| void fibril_remove_manager(void) |
| void fibril_rwlock_write_lock(fibril_rwlock_t *frw) |
| { |
| futex_down(&fibril_futex); |
| if (list_empty(&manager_list)) { |
| futex_up(&fibril_futex); |
| return; |
| } |
| list_remove(manager_list.next); |
| futex_up(&fibril_futex); |
| fibril_mutex_lock(&frw->fm); |
| } |
| |
| /** Return fibril id of the currently running fibril. |
| * |
| * @return Fibril ID of the currently running fibril. |
| */ |
| fid_t fibril_get_id(void) |
| void fibril_rwlock_read_unlock(fibril_rwlock_t *frw) |
| { |
| return (fid_t) __tcb_get()->fibril_data; |
| fibril_mutex_unlock(&frw->fm); |
| } |
| |
| /** Disable preemption |
| * |
| * If the fibril wants to send several message in a row and does not want to be |
| * preempted, it should start async_serialize_start() in the beginning of |
| * communication and async_serialize_end() in the end. If it is a true |
| * multithreaded application, it should protect the communication channel by a |
| * futex as well. Interrupt messages can still be preempted. |
| */ |
| void fibril_inc_sercount(void) |
| void fibril_rwlock_write_unlock(fibril_rwlock_t *frw) |
| { |
| serialization_count++; |
| fibril_mutex_unlock(&frw->fm); |
| } |
| |
| /** Restore the preemption counter to the previous state. */ |
| void fibril_dec_sercount(void) |
| { |
| serialization_count--; |
| } |
| |
| /** @} |
| */ |