/* Semaphore code. Lots of "todo" items*/ /* ** Copyright 2001, Travis Geiselbrecht. All rights reserved. ** Distributed under the terms of the NewOS License. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include struct sem_entry { sem_id id; int count; struct thread_queue q; char *name; int lock; proc_id owner; // if set to -1, means owned by a port }; #define MAX_SEMS 4096 static struct sem_entry *sems = NULL; static region_id sem_region = 0; static bool sems_active = false; static sem_id next_sem = 0; static int sem_spinlock = 0; #define GRAB_SEM_LIST_LOCK() acquire_spinlock(&sem_spinlock) #define RELEASE_SEM_LIST_LOCK() release_spinlock(&sem_spinlock) #define GRAB_SEM_LOCK(s) acquire_spinlock(&(s).lock) #define RELEASE_SEM_LOCK(s) release_spinlock(&(s).lock) // used in functions that may put a bunch of threads in the run q at once #define READY_THREAD_CACHE_SIZE 16 static int remove_thread_from_sem(struct thread *t, struct sem_entry *sem, struct thread_queue *queue, int sem_errcode); struct sem_timeout_args { thread_id blocked_thread; sem_id blocked_sem_id; int sem_count; }; static void dump_sem_list(int argc, char **argv) { int i; for(i=0; i= 0) { dprintf("%p\tid: 0x%x\t\tname: '%s'\n", &sems[i], sems[i].id, sems[i].name); } } } static void _dump_sem_info(struct sem_entry *sem) { dprintf("SEM: %p\n", sem); dprintf("name: '%s'\n", sem->name); dprintf("owner: 0x%x\n", sem->owner); dprintf("count: 0x%x\n", sem->count); dprintf("queue: head %p tail %p\n", sem->q.head, sem->q.tail); } static void dump_sem_info(int argc, char **argv) { int i; if(argc < 2) { dprintf("sem: not enough arguments\n"); return; } // if the argument looks like a hex number, treat it as such if(strlen(argv[1]) > 2 && argv[1][0] == '0' && argv[1][1] == 'x') { unsigned long num = atoul(argv[1]); if(num > KERNEL_BASE && num <= (KERNEL_BASE + (KERNEL_SIZE - 1))) { // XXX semi-hack _dump_sem_info((struct sem_entry *)num); return; } else { unsigned slot = num % MAX_SEMS; if(sems[slot].id != (int)num) { dprintf("sem 0x%lx doesn't exist!\n", num); return; } _dump_sem_info(&sems[slot]); return; } } // walk through the sem list, trying to match name for(i=0; i= next_sem % MAX_SEMS) { next_sem += i - next_sem % MAX_SEMS; } else { next_sem += MAX_SEMS - (next_sem % MAX_SEMS - i); } sems[i].id = next_sem++; sems[i].lock = 0; GRAB_SEM_LOCK(sems[i]); RELEASE_SEM_LIST_LOCK(); sems[i].q.tail = NULL; sems[i].q.head = NULL; sems[i].count = count; sems[i].name = temp_name; sems[i].owner = owner; retval = sems[i].id; RELEASE_SEM_LOCK(sems[i]); goto out; } } //err: RELEASE_SEM_LIST_LOCK(); kfree(temp_name); out: int_restore_interrupts(state); return retval; } sem_id create_sem(int count, const char *name) { return create_sem_etc(count, name, proc_get_kernel_proc_id()); } int delete_sem(sem_id id) { return delete_sem_etc(id, 0); } int delete_sem_etc(sem_id id, int return_code) { int slot; int state; int err = B_NO_ERROR; struct thread *t; int released_threads; char *old_name; struct thread_queue release_queue; if(sems_active == false) return B_NO_MORE_SEMS; if(id < 0) return B_BAD_SEM_ID; slot = id % MAX_SEMS; state = int_disable_interrupts(); GRAB_SEM_LOCK(sems[slot]); if(sems[slot].id != id) { RELEASE_SEM_LOCK(sems[slot]); int_restore_interrupts(state); dprintf("delete_sem: invalid sem_id %d\n", id); return B_BAD_SEM_ID; } released_threads = 0; release_queue.head = release_queue.tail = NULL; // free any threads waiting for this semaphore while((t = thread_dequeue(&sems[slot].q)) != NULL) { t->state = THREAD_STATE_READY; t->sem_errcode = B_BAD_SEM_ID; t->sem_deleted_retcode = return_code; t->sem_count = 0; thread_enqueue(t, &release_queue); released_threads++; } sems[slot].id = -1; old_name = sems[slot].name; sems[slot].name = NULL; RELEASE_SEM_LOCK(sems[slot]); if(released_threads > 0) { GRAB_THREAD_LOCK(); while((t = thread_dequeue(&release_queue)) != NULL) { thread_enqueue_run_q(t); } thread_resched(); RELEASE_THREAD_LOCK(); } int_restore_interrupts(state); kfree(old_name); return err; } // Called from a timer handler. Wakes up a semaphore static int sem_timeout(void *data) { struct sem_timeout_args *args = (struct sem_timeout_args *)data; struct thread *t; int slot; int state; struct thread_queue wakeup_queue; t = thread_get_thread_struct(args->blocked_thread); if(t == NULL) return INT_NO_RESCHEDULE; slot = args->blocked_sem_id % MAX_SEMS; state = int_disable_interrupts(); GRAB_SEM_LOCK(sems[slot]); // dprintf("sem_timeout: called on 0x%x sem %d, tid %d\n", to, to->sem_id, to->thread_id); if(sems[slot].id != args->blocked_sem_id) { // this thread was not waiting on this semaphore panic("sem_timeout: thid %d was trying to wait on sem %d which doesn't exist!\n", args->blocked_thread, args->blocked_sem_id); } wakeup_queue.head = wakeup_queue.tail = NULL; remove_thread_from_sem(t, &sems[slot], &wakeup_queue, B_TIMED_OUT); RELEASE_SEM_LOCK(sems[slot]); GRAB_THREAD_LOCK(); // put the threads in the run q here to make sure we dont deadlock in sem_interrupt_thread while((t = thread_dequeue(&wakeup_queue)) != NULL) { thread_enqueue_run_q(t); } RELEASE_THREAD_LOCK(); int_restore_interrupts(state); return INT_RESCHEDULE; } int acquire_sem(sem_id id) { return acquire_sem_etc(id, 1, 0, 0); } int acquire_sem_etc(sem_id id, int count, int flags, bigtime_t timeout) { int slot = id % MAX_SEMS; int state; int err = 0; if(sems_active == false) return B_NO_MORE_SEMS; if(id < 0) { dprintf("acquire_sem_etc: invalid sem handle %d\n", id); return B_BAD_SEM_ID; } if(count <= 0) return ERR_INVALID_ARGS; state = int_disable_interrupts(); GRAB_SEM_LOCK(sems[slot]); if(sems[slot].id != id) { dprintf("acquire_sem_etc: bad sem_id %d\n", id); err = B_BAD_SEM_ID; goto err; } if(sems[slot].count - count < 0 && (flags & B_TIMEOUT) != 0 && timeout <= 0) { // immediate timeout err = ERR_SEM_TIMED_OUT; goto err; } if((sems[slot].count -= count) < 0) { // we need to block struct thread *t = thread_get_current_thread(); struct timer_event timer; // stick it on the stack, since we may be blocking here struct sem_timeout_args args; // do a quick check to see if the thread has any pending kill signals // this should catch most of the cases where the thread had a signal if((flags & B_CAN_INTERRUPT) && (t->pending_signals & SIG_KILL)) { sems[slot].count += count; err = EINTR; goto err; } t->next_state = THREAD_STATE_WAITING; t->sem_flags = flags; t->sem_blocking = id; t->sem_acquire_count = count; t->sem_count = min(-sems[slot].count, count); // store the count we need to restore upon release t->sem_deleted_retcode = 0; t->sem_errcode = B_NO_ERROR; thread_enqueue(t, &sems[slot].q); if((flags & (B_TIMEOUT | B_ABSOLUTE_TIMEOUT)) != 0) { int the_timeout = timeout; // dprintf("sem_acquire_etc: setting timeout sem for %d %d usecs, semid %d, tid %d\n", // timeout, sem_id, t->id); // set up an event to go off with the thread struct as the data if (flags & B_ABSOLUTE_TIMEOUT) the_timeout -= system_time(); args.blocked_sem_id = id; args.blocked_thread = t->id; args.sem_count = count; timer_setup_timer(&sem_timeout, &args, &timer); timer_set_event(the_timeout, TIMER_MODE_ONESHOT, &timer); } RELEASE_SEM_LOCK(sems[slot]); GRAB_THREAD_LOCK(); // check again to see if a kill signal is pending. // it may have been delivered while setting up the sem, though it's pretty unlikely if((flags & B_CAN_INTERRUPT) && (t->pending_signals & SIG_KILL)) { struct thread_queue wakeup_queue; // ok, so a tiny race happened where a signal was delivered to this thread while // it was setting up the sem. We can only be sure a signal wasn't delivered // here, since the threadlock is held. The previous check would have found most // instances, but there was a race, so we have to handle it. It'll be more messy... wakeup_queue.head = wakeup_queue.tail = NULL; GRAB_SEM_LOCK(sems[slot]); if(sems[slot].id == id) { remove_thread_from_sem(t, &sems[slot], &wakeup_queue, EINTR); } RELEASE_SEM_LOCK(sems[slot]); while((t = thread_dequeue(&wakeup_queue)) != NULL) { thread_enqueue_run_q(t); } // fall through and reschedule since another thread with a higher priority may have been woken up } thread_resched(); RELEASE_THREAD_LOCK(); if((flags & B_TIMEOUT) != 0) { if(t->sem_errcode != ERR_SEM_TIMED_OUT) { // cancel the timer event, the sem may have been deleted or interrupted // with the timer still active timer_cancel_event(&timer); } } int_restore_interrupts(state); return t->sem_errcode; } err: RELEASE_SEM_LOCK(sems[slot]); int_restore_interrupts(state); return err; } int release_sem(sem_id id) { return release_sem_etc(id, 1, 0); } int release_sem_etc(sem_id id, int count, int flags) { int slot = id % MAX_SEMS; int state; int released_threads = 0; int err = 0; struct thread_queue release_queue; if(sems_active == false) return B_NO_MORE_SEMS; if(id < 0) return B_BAD_SEM_ID; if(count <= 0) return ERR_INVALID_ARGS; state = int_disable_interrupts(); GRAB_SEM_LOCK(sems[slot]); if(sems[slot].id != id) { dprintf("sem_release_etc: invalid sem_id %d\n", id); err = B_BAD_SEM_ID; goto err; } // clear out a queue we will use to hold all of the threads that we will have to // put back into the run list. This is done so the thread lock wont be held // while this sems lock is held since the two locks are grabbed in the other // order in sem_interrupt_thread. release_queue.head = release_queue.tail = NULL; while(count > 0) { int delta = count; if(sems[slot].count < 0) { struct thread *t = thread_lookat_queue(&sems[slot].q); delta = min(count, t->sem_count); t->sem_count -= delta; if(t->sem_count <= 0) { // release this thread t = thread_dequeue(&sems[slot].q); thread_enqueue(t, &release_queue); t->state = THREAD_STATE_READY; released_threads++; t->sem_count = 0; t->sem_deleted_retcode = 0; } } sems[slot].count += delta; count -= delta; } RELEASE_SEM_LOCK(sems[slot]); // pull off any items in the release queue and put them in the run queue if(released_threads > 0) { struct thread *t; GRAB_THREAD_LOCK(); while((t = thread_dequeue(&release_queue)) != NULL) { thread_enqueue_run_q(t); } if((flags & B_DO_NOT_RESCHEDULE) == 0) { thread_resched(); } RELEASE_THREAD_LOCK(); } goto outnolock; err: RELEASE_SEM_LOCK(sems[slot]); outnolock: int_restore_interrupts(state); return err; } int get_sem_count(sem_id id, int32* thread_count) { int slot; int state; // int count; if(sems_active == false) return B_NO_MORE_SEMS; if(id < 0) return B_BAD_SEM_ID; if (thread_count == NULL) return ERR_INVALID_ARGS; slot = id % MAX_SEMS; state = int_disable_interrupts(); GRAB_SEM_LOCK(sems[slot]); if(sems[slot].id != id) { RELEASE_SEM_LOCK(sems[slot]); int_restore_interrupts(state); dprintf("sem_get_count: invalid sem_id %d\n", id); return B_BAD_SEM_ID; } *thread_count = sems[slot].count; RELEASE_SEM_LOCK(sems[slot]); int_restore_interrupts(state); return B_NO_ERROR; } int _get_sem_info(sem_id id, struct sem_info *info, size_t sz) { int state; int slot; if(sems_active == false) return B_NO_MORE_SEMS; if(id < 0) return B_BAD_SEM_ID; if (info == NULL) return ERR_INVALID_ARGS; slot = id % MAX_SEMS; state = int_disable_interrupts(); GRAB_SEM_LOCK(sems[slot]); if(sems[slot].id != id) { RELEASE_SEM_LOCK(sems[slot]); int_restore_interrupts(state); dprintf("get_sem_info: invalid sem_id %d\n", id); return B_BAD_SEM_ID; } info->sem = sems[slot].id; info->proc = sems[slot].owner; strncpy(info->name, sems[slot].name, SYS_MAX_OS_NAME_LEN-1); info->count = sems[slot].count; info->latest_holder = sems[slot].q.head->id; // XXX not sure if this is correct RELEASE_SEM_LOCK(sems[slot]); int_restore_interrupts(state); return B_NO_ERROR; } int _get_next_sem_info(proc_id proc, uint32 *cookie, struct sem_info *info, size_t sz) { int state; int slot; if(sems_active == false) return B_NO_MORE_SEMS; if (cookie == NULL) return ERR_INVALID_ARGS; if (proc < 0) return ERR_INVALID_ARGS; // prevents sems[].owner == -1 >= means owned by a port if (*cookie == NULL) { // return first found slot = 0; } else { // start at index cookie, but check cookie against MAX_PORTS slot = *cookie; if (slot >= MAX_SEMS) return B_BAD_SEM_ID; } // spinlock state = int_disable_interrupts(); GRAB_SEM_LIST_LOCK(); while (slot < MAX_SEMS) { GRAB_SEM_LOCK(sems[slot]); if (sems[slot].id != -1) if (sems[slot].owner == proc) { // found one! info->sem = sems[slot].id; info->proc = sems[slot].owner; strncpy(info->name, sems[slot].name, SYS_MAX_OS_NAME_LEN-1); info->count = sems[slot].count; info->latest_holder = sems[slot].q.head->id; // XXX not sure if this is the latest holder, or the next holder... RELEASE_SEM_LOCK(sems[slot]); slot++; break; } RELEASE_SEM_LOCK(sems[slot]); slot++; } RELEASE_SEM_LIST_LOCK(); int_restore_interrupts(state); if (slot == MAX_SEMS) return ERR_SEM_NOT_FOUND; *cookie = slot; return B_NO_ERROR; } int set_sem_owner(sem_id id, proc_id proc) { int state; int slot; if(sems_active == false) return B_NO_MORE_SEMS; if(id < 0) return B_BAD_SEM_ID; if (proc < NULL) return ERR_INVALID_ARGS; // XXX: todo check if proc exists // if (proc_get_proc_struct(proc) == NULL) // return B_BAD_SEM_ID; // proc_id doesn't exist right now slot = id % MAX_SEMS; state = int_disable_interrupts(); GRAB_SEM_LOCK(sems[slot]); if(sems[slot].id != id) { RELEASE_SEM_LOCK(sems[slot]); int_restore_interrupts(state); dprintf("set_sem_owner: invalid sem_id %d\n", id); return B_BAD_SEM_ID; } sems[slot].owner = proc; RELEASE_SEM_LOCK(sems[slot]); int_restore_interrupts(state); return B_NO_ERROR; } // Wake up a thread that's blocked on a semaphore // this function must be entered with interrupts disabled and THREADLOCK held int sem_interrupt_thread(struct thread *t) { // struct thread *t1; int slot; // int state; struct thread_queue wakeup_queue; // dprintf("sem_interrupt_thread: called on thread %p (%d), blocked on sem 0x%x\n", t, t->id, t->sem_blocking); if(t->state != THREAD_STATE_WAITING) return ERR_INVALID_ARGS; if(t->sem_blocking < 0) return ERR_INVALID_ARGS; if((t->sem_flags & B_CAN_INTERRUPT) == 0) return ERR_SEM_NOT_INTERRUPTABLE; slot = t->sem_blocking % MAX_SEMS; GRAB_SEM_LOCK(sems[slot]); if(sems[slot].id != t->sem_blocking) { panic("sem_interrupt_thread: thread 0x%x sez it's blocking on sem 0x%x, but that sem doesn't exist!\n", t->id, t->sem_blocking); } wakeup_queue.head = wakeup_queue.tail = NULL; if(remove_thread_from_sem(t, &sems[slot], &wakeup_queue, EINTR) == ERR_NOT_FOUND) panic("sem_interrupt_thread: thread 0x%x not found in sem 0x%x's wait queue\n", t->id, t->sem_blocking); RELEASE_SEM_LOCK(sems[slot]); while((t = thread_dequeue(&wakeup_queue)) != NULL) { thread_enqueue_run_q(t); } return B_NO_ERROR; } // forcibly removes a thread from a semaphores wait q. May have to wake up other threads in the // process. All threads that need to be woken up are added to the passed in thread_queue. // must be called with sem lock held static int remove_thread_from_sem(struct thread *t, struct sem_entry *sem, struct thread_queue *queue, int sem_errcode) { struct thread *t1; // remove the thread from the queue and place it in the supplied queue t1 = thread_dequeue_id(&sem->q, t->id); if(t != t1) return ERR_NOT_FOUND; sem->count += t->sem_acquire_count; t->state = THREAD_STATE_READY; t->sem_errcode = sem_errcode; thread_enqueue(t, queue); // now see if more threads need to be woken up while(sem->count > 0 && (t1 = thread_lookat_queue(&sem->q))) { int delta = min(t->sem_count, sem->count); t->sem_count -= delta; if(t->sem_count <= 0) { t = thread_dequeue(&sem->q); t->state = THREAD_STATE_READY; thread_enqueue(t, queue); } sem->count -= delta; } return B_NO_ERROR; } /* this function cycles through the sem table, deleting all the sems that are owned by the passed proc_id */ int sem_delete_owned_sems(proc_id owner) { int state; int i; int count = 0; if (owner < 0) return B_BAD_SEM_ID; state = int_disable_interrupts(); GRAB_SEM_LIST_LOCK(); for(i=0; i= KERNEL_BASE && (addr)uname <= KERNEL_TOP) return ERR_VM_BAD_USER_MEMORY; rc = user_strncpy(name, uname, SYS_MAX_OS_NAME_LEN-1); if(rc < 0) return rc; name[SYS_MAX_OS_NAME_LEN-1] = 0; return create_sem_etc(count, name, proc_get_current_proc_id()); } else { return create_sem_etc(count, NULL, proc_get_current_proc_id()); } } int user_delete_sem(sem_id id) { return delete_sem(id); } int user_delete_sem_etc(sem_id id, int return_code) { return delete_sem_etc(id, return_code); } int user_acquire_sem(sem_id id) { return user_acquire_sem_etc(id, 1, 0, 0); } int user_acquire_sem_etc(sem_id id, int count, int flags, bigtime_t timeout) { flags = flags | B_CAN_INTERRUPT; return acquire_sem_etc(id, count, flags, timeout); } int user_release_sem(sem_id id) { return release_sem_etc(id, 1, 0); } int user_release_sem_etc(sem_id id, int count, int flags) { return release_sem_etc(id, count, flags); } int user_get_sem_count(sem_id uid, int32* uthread_count) { int32 thread_count; int rc, rc2; rc = get_sem_count(uid, &thread_count); rc2 = user_memcpy(uthread_count, &thread_count, sizeof(int32)); if(rc2 < 0) return rc2; return rc; } int user_get_sem_info(sem_id uid, struct sem_info *uinfo, size_t sz) { struct sem_info info; int rc, rc2; if((addr)uinfo >= KERNEL_BASE && (addr)uinfo <= KERNEL_TOP) return ERR_VM_BAD_USER_MEMORY; rc = _get_sem_info(uid, &info, sz); rc2 = user_memcpy(uinfo, &info, sz); if(rc2 < 0) return rc2; return rc; } int user_get_next_sem_info(proc_id uproc, uint32 *ucookie, struct sem_info *uinfo, size_t sz) { struct sem_info info; uint32 cookie; int rc, rc2; if((addr)uinfo >= KERNEL_BASE && (addr)uinfo <= KERNEL_TOP) return ERR_VM_BAD_USER_MEMORY; rc2 = user_memcpy(&cookie, ucookie, sizeof(uint32)); if(rc2 < 0) return rc2; rc = _get_next_sem_info(uproc, &cookie, &info, sz); rc2 = user_memcpy(uinfo, &info, sz); if(rc2 < 0) return rc2; rc2 = user_memcpy(ucookie, &cookie, sizeof(uint32)); if(rc2 < 0) return rc2; return rc; } int user_set_sem_owner(sem_id uid, proc_id uproc) { return set_sem_owner(uid, uproc); }