sched.c

Linux Kernel 2.6.9 for OMAP1710

	spin_unlock(&rpc_sched_lock);

	if (clnt) {
		atomic_inc(&clnt->cl_users);
		if (clnt->cl_softrtry)
			task->tk_flags |= RPC_TASK_SOFT;
		if (!clnt->cl_intr)
			task->tk_flags |= RPC_TASK_NOINTR;
	}

#ifdef RPC_DEBUG
	task->tk_magic = 0xf00baa;
	task->tk_pid = rpc_task_id++;
#endif
	dprintk("RPC: %4d new task procpid %d\n", task->tk_pid,
				current->pid);
}

static struct rpc_task *
rpc_alloc_task(void)
{
	return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
}

static void
rpc_default_free_task(struct rpc_task *task)
{
	dprintk("RPC: %4d freeing task\n", task->tk_pid);
	mempool_free(task, rpc_task_mempool);
}

/*
 * Create a new task for the specified client.  We have to
 * clean up after an allocation failure, as the client may
 * have specified "oneshot".
 */
struct rpc_task *
rpc_new_task(struct rpc_clnt *clnt, rpc_action callback, int flags)
{
	struct rpc_task	*task;

	task = rpc_alloc_task();
	if (!task)
		goto cleanup;

	rpc_init_task(task, clnt, callback, flags);

	/* Replace tk_release */
	task->tk_release = rpc_default_free_task;

	dprintk("RPC: %4d allocated task\n", task->tk_pid);
	task->tk_flags |= RPC_TASK_DYNAMIC;
out:
	return task;

cleanup:
	/* Check whether to release the client */
	if (clnt) {
		printk("rpc_new_task: failed, users=%d, oneshot=%d\n",
			atomic_read(&clnt->cl_users), clnt->cl_oneshot);
		atomic_inc(&clnt->cl_users); /* pretend we were used ... */
		rpc_release_client(clnt);
	}
	goto out;
}

void
rpc_release_task(struct rpc_task *task)
{
	dprintk("RPC: %4d release task\n", task->tk_pid);

#ifdef RPC_DEBUG
	if (task->tk_magic != 0xf00baa) {
		printk(KERN_ERR "RPC: attempt to release a non-existing task!\n");
		rpc_debug = ~0;
		rpc_show_tasks();
		return;
	}
#endif

	/* Remove from global task list */
	spin_lock(&rpc_sched_lock);
	list_del(&task->tk_task);
	spin_unlock(&rpc_sched_lock);

	/* Protect the execution below. */
	spin_lock_bh(&rpc_queue_lock);

	/* Disable timer to prevent zombie wakeup */
	__rpc_disable_timer(task);

	/* Remove from any wait queue we're still on */
	__rpc_remove_wait_queue(task);

	task->tk_active = 0;

	spin_unlock_bh(&rpc_queue_lock);

	/* Synchronously delete any running timer */
	rpc_delete_timer(task);

	/* Release resources */
	if (task->tk_rqstp)
		xprt_release(task);
	if (task->tk_msg.rpc_cred)
		rpcauth_unbindcred(task);
	rpc_free(task);
	if (task->tk_client) {
		rpc_release_client(task->tk_client);
		task->tk_client = NULL;
	}

#ifdef RPC_DEBUG
	task->tk_magic = 0;
#endif
	if (task->tk_release)
		task->tk_release(task);
}

/**
 * rpc_find_parent - find the parent of a child task.
 * @child: child task
 *
 * Checks that the parent task is still sleeping on the
 * queue 'childq'. If so returns a pointer to the parent.
 * Upon failure returns NULL.
 *
 * Caller must hold rpc_queue_lock
 */
static inline struct rpc_task *
rpc_find_parent(struct rpc_task *child)
{
	struct rpc_task	*task, *parent;
	struct list_head *le;

	parent = (struct rpc_task *) child->tk_calldata;
	task_for_each(task, le, &childq.tasks[0])
		if (task == parent)
			return parent;

	return NULL;
}

static void
rpc_child_exit(struct rpc_task *child)
{
	struct rpc_task	*parent;

	spin_lock_bh(&rpc_queue_lock);
	if ((parent = rpc_find_parent(child)) != NULL) {
		parent->tk_status = child->tk_status;
		__rpc_wake_up_task(parent);
	}
	spin_unlock_bh(&rpc_queue_lock);
}

/*
 * Note: rpc_new_task releases the client after a failure.
 */
struct rpc_task *
rpc_new_child(struct rpc_clnt *clnt, struct rpc_task *parent)
{
	struct rpc_task	*task;

	task = rpc_new_task(clnt, NULL, RPC_TASK_ASYNC | RPC_TASK_CHILD);
	if (!task)
		goto fail;
	task->tk_exit = rpc_child_exit;
	task->tk_calldata = parent;
	return task;

fail:
	parent->tk_status = -ENOMEM;
	return NULL;
}

void
rpc_run_child(struct rpc_task *task, struct rpc_task *child, rpc_action func)
{
	spin_lock_bh(&rpc_queue_lock);
	/* N.B. Is it possible for the child to have already finished? */
	__rpc_sleep_on(&childq, task, func, NULL);
	rpc_schedule_run(child);
	spin_unlock_bh(&rpc_queue_lock);
}

/*
 * Kill all tasks for the given client.
 * XXX: kill their descendants as well?
 */
void
rpc_killall_tasks(struct rpc_clnt *clnt)
{
	struct rpc_task	*rovr;
	struct list_head *le;

	dprintk("RPC:      killing all tasks for client %p\n", clnt);

	/*
	 * Spin lock all_tasks to prevent changes...
	 */
	spin_lock(&rpc_sched_lock);
	alltask_for_each(rovr, le, &all_tasks)
		if (!clnt || rovr->tk_client == clnt) {
			rovr->tk_flags |= RPC_TASK_KILLED;
			rpc_exit(rovr, -EIO);
			rpc_wake_up_task(rovr);
		}
	spin_unlock(&rpc_sched_lock);
}

static DECLARE_MUTEX_LOCKED(rpciod_running);

static inline int
rpciod_task_pending(void)
{
	return !list_empty(&schedq.tasks[0]);
}


/*
 * This is the rpciod kernel thread
 */
static int
rpciod(void *ptr)
{
	int		rounds = 0;

	lock_kernel();
	/*
	 * Let our maker know we're running ...
	 */
	rpciod_pid = current->pid;
	up(&rpciod_running);

	daemonize("rpciod");
	allow_signal(SIGKILL);

	dprintk("RPC: rpciod starting (pid %d)\n", rpciod_pid);
	spin_lock_bh(&rpc_queue_lock);
	while (rpciod_users) {
		DEFINE_WAIT(wait);
		if (signalled()) {
			spin_unlock_bh(&rpc_queue_lock);
			rpciod_killall();
			flush_signals(current);
			spin_lock_bh(&rpc_queue_lock);
		}
		__rpc_schedule();
		if (current->flags & PF_FREEZE) {
			spin_unlock_bh(&rpc_queue_lock);
			refrigerator(PF_FREEZE);
			spin_lock_bh(&rpc_queue_lock);
		}

		if (++rounds >= 64) {	/* safeguard */
			spin_unlock_bh(&rpc_queue_lock);
			schedule();
			rounds = 0;
			spin_lock_bh(&rpc_queue_lock);
		}

		dprintk("RPC: rpciod back to sleep\n");
		prepare_to_wait(&rpciod_idle, &wait, TASK_INTERRUPTIBLE);
		if (!rpciod_task_pending() && !signalled()) {
			spin_unlock_bh(&rpc_queue_lock);
			schedule();
			rounds = 0;
			spin_lock_bh(&rpc_queue_lock);
		}
		finish_wait(&rpciod_idle, &wait);
		dprintk("RPC: switch to rpciod\n");
	}
	spin_unlock_bh(&rpc_queue_lock);

	dprintk("RPC: rpciod shutdown commences\n");
	if (!list_empty(&all_tasks)) {
		printk(KERN_ERR "rpciod: active tasks at shutdown?!\n");
		rpciod_killall();
	}

	dprintk("RPC: rpciod exiting\n");
	unlock_kernel();

	rpciod_pid = 0;
	complete_and_exit(&rpciod_killer, 0);
	return 0;
}

static void
rpciod_killall(void)
{
	unsigned long flags;

	while (!list_empty(&all_tasks)) {
		clear_thread_flag(TIF_SIGPENDING);
		rpc_killall_tasks(NULL);
		spin_lock_bh(&rpc_queue_lock);
		__rpc_schedule();
		spin_unlock_bh(&rpc_queue_lock);
		if (!list_empty(&all_tasks)) {
			dprintk("rpciod_killall: waiting for tasks to exit\n");
			yield();
		}
	}

	spin_lock_irqsave(&current->sighand->siglock, flags);
	recalc_sigpending();
	spin_unlock_irqrestore(&current->sighand->siglock, flags);
}

/*
 * Start up the rpciod process if it's not already running.
 */
int
rpciod_up(void)
{
	int error = 0;

	down(&rpciod_sema);
	dprintk("rpciod_up: pid %d, users %d\n", rpciod_pid, rpciod_users);
	rpciod_users++;
	if (rpciod_pid)
		goto out;
	/*
	 * If there's no pid, we should be the first user.
	 */
	if (rpciod_users > 1)
		printk(KERN_WARNING "rpciod_up: no pid, %d users??\n", rpciod_users);
	/*
	 * Create the rpciod thread and wait for it to start.
	 */
	error = kernel_thread(rpciod, NULL, 0);
	if (error < 0) {
		printk(KERN_WARNING "rpciod_up: create thread failed, error=%d\n", error);
		rpciod_users--;
		goto out;
	}
	down(&rpciod_running);
	error = 0;
out:
	up(&rpciod_sema);
	return error;
}

void
rpciod_down(void)
{
	down(&rpciod_sema);
	dprintk("rpciod_down pid %d sema %d\n", rpciod_pid, rpciod_users);
	if (rpciod_users) {
		if (--rpciod_users)
			goto out;
	} else
		printk(KERN_WARNING "rpciod_down: pid=%d, no users??\n", rpciod_pid);

	if (!rpciod_pid) {
		dprintk("rpciod_down: Nothing to do!\n");
		goto out;
	}

	kill_proc(rpciod_pid, SIGKILL, 1);
	wait_for_completion(&rpciod_killer);
 out:
	up(&rpciod_sema);
}

#ifdef RPC_DEBUG
void rpc_show_tasks(void)
{
	struct list_head *le;
	struct rpc_task *t;

	spin_lock(&rpc_sched_lock);
	if (list_empty(&all_tasks)) {
		spin_unlock(&rpc_sched_lock);
		return;
	}
	printk("-pid- proc flgs status -client- -prog- --rqstp- -timeout "
		"-rpcwait -action- --exit--\n");
	alltask_for_each(t, le, &all_tasks)
		printk("%05d %04d %04x %06d %8p %6d %8p %08ld %8s %8p %8p\n",
			t->tk_pid,
			(t->tk_msg.rpc_proc ? t->tk_msg.rpc_proc->p_proc : -1),
			t->tk_flags, t->tk_status,
			t->tk_client,
			(t->tk_client ? t->tk_client->cl_prog : 0),
			t->tk_rqstp, t->tk_timeout,
			rpc_qname(t->tk_rpcwait),
			t->tk_action, t->tk_exit);
	spin_unlock(&rpc_sched_lock);
}
#endif

void
rpc_destroy_mempool(void)
{
	if (rpc_buffer_mempool)
		mempool_destroy(rpc_buffer_mempool);
	if (rpc_task_mempool)
		mempool_destroy(rpc_task_mempool);
	if (rpc_task_slabp && kmem_cache_destroy(rpc_task_slabp))
		printk(KERN_INFO "rpc_task: not all structures were freed\n");
	if (rpc_buffer_slabp && kmem_cache_destroy(rpc_buffer_slabp))
		printk(KERN_INFO "rpc_buffers: not all structures were freed\n");
}

int
rpc_init_mempool(void)
{
	rpc_task_slabp = kmem_cache_create("rpc_tasks",
					     sizeof(struct rpc_task),
					     0, SLAB_HWCACHE_ALIGN,
					     NULL, NULL);
	if (!rpc_task_slabp)
		goto err_nomem;
	rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
					     RPC_BUFFER_MAXSIZE,
					     0, SLAB_HWCACHE_ALIGN,
					     NULL, NULL);
	if (!rpc_buffer_slabp)
		goto err_nomem;
	rpc_task_mempool = mempool_create(RPC_TASK_POOLSIZE,
					    mempool_alloc_slab,
					    mempool_free_slab,
					    rpc_task_slabp);
	if (!rpc_task_mempool)
		goto err_nomem;
	rpc_buffer_mempool = mempool_create(RPC_BUFFER_POOLSIZE,
					    mempool_alloc_slab,
					    mempool_free_slab,
					    rpc_buffer_slabp);
	if (!rpc_buffer_mempool)
		goto err_nomem;
	return 0;
err_nomem:
	rpc_destroy_mempool();
	return -ENOMEM;
}