mux.c

linux 内核源代码

			P9_DPRINTK(P9_DEBUG_MUX, "schedule write work %p\n", m);
			queue_work(p9_mux_wq, &m->wq);
		} else
			clear_bit(Wworksched, &m->wsched);
	} else
		clear_bit(Wworksched, &m->wsched);

	return;

error:
	p9_conn_cancel(m, err);
	clear_bit(Wworksched, &m->wsched);
}

static void process_request(struct p9_conn *m, struct p9_req *req)
{
	int ecode;
	struct p9_str *ename;

	if (!req->err && req->rcall->id == P9_RERROR) {
		ecode = req->rcall->params.rerror.errno;
		ename = &req->rcall->params.rerror.error;

		P9_DPRINTK(P9_DEBUG_MUX, "Rerror %.*s\n", ename->len,
								ename->str);

		if (*m->extended)
			req->err = -ecode;

		if (!req->err) {
			req->err = p9_errstr2errno(ename->str, ename->len);

			if (!req->err) {	/* string match failed */
				PRINT_FCALL_ERROR("unknown error", req->rcall);
			}

			if (!req->err)
				req->err = -ESERVERFAULT;
		}
	} else if (req->tcall && req->rcall->id != req->tcall->id + 1) {
		P9_DPRINTK(P9_DEBUG_ERROR,
				"fcall mismatch: expected %d, got %d\n",
				req->tcall->id + 1, req->rcall->id);
		if (!req->err)
			req->err = -EIO;
	}
}

/**
 * p9_read_work - called when there is some data to be read from a transport
 */
static void p9_read_work(struct work_struct *work)
{
	int n, err;
	struct p9_conn *m;
	struct p9_req *req, *rptr, *rreq;
	struct p9_fcall *rcall;
	char *rbuf;

	m = container_of(work, struct p9_conn, rq);

	if (m->err < 0)
		return;

	rcall = NULL;
	P9_DPRINTK(P9_DEBUG_MUX, "start mux %p pos %d\n", m, m->rpos);

	if (!m->rcall) {
		m->rcall =
		    kmalloc(sizeof(struct p9_fcall) + m->msize, GFP_KERNEL);
		if (!m->rcall) {
			err = -ENOMEM;
			goto error;
		}

		m->rbuf = (char *)m->rcall + sizeof(struct p9_fcall);
		m->rpos = 0;
	}

	clear_bit(Rpending, &m->wsched);
	err = m->trans->read(m->trans, m->rbuf + m->rpos, m->msize - m->rpos);
	P9_DPRINTK(P9_DEBUG_MUX, "mux %p got %d bytes\n", m, err);
	if (err == -EAGAIN) {
		clear_bit(Rworksched, &m->wsched);
		return;
	}

	if (err <= 0)
		goto error;

	m->rpos += err;
	while (m->rpos > 4) {
		n = le32_to_cpu(*(__le32 *) m->rbuf);
		if (n >= m->msize) {
			P9_DPRINTK(P9_DEBUG_ERROR,
				"requested packet size too big: %d\n", n);
			err = -EIO;
			goto error;
		}

		if (m->rpos < n)
			break;

		err =
		    p9_deserialize_fcall(m->rbuf, n, m->rcall, *m->extended);
		if (err < 0) {
			goto error;
		}

#ifdef CONFIG_NET_9P_DEBUG
		if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
			char buf[150];

			p9_printfcall(buf, sizeof(buf), m->rcall,
				*m->extended);
			printk(KERN_NOTICE ">>> %p %s\n", m, buf);
		}
#endif

		rcall = m->rcall;
		rbuf = m->rbuf;
		if (m->rpos > n) {
			m->rcall = kmalloc(sizeof(struct p9_fcall) + m->msize,
					   GFP_KERNEL);
			if (!m->rcall) {
				err = -ENOMEM;
				goto error;
			}

			m->rbuf = (char *)m->rcall + sizeof(struct p9_fcall);
			memmove(m->rbuf, rbuf + n, m->rpos - n);
			m->rpos -= n;
		} else {
			m->rcall = NULL;
			m->rbuf = NULL;
			m->rpos = 0;
		}

		P9_DPRINTK(P9_DEBUG_MUX, "mux %p fcall id %d tag %d\n", m,
							rcall->id, rcall->tag);

		req = NULL;
		spin_lock(&m->lock);
		list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
			if (rreq->tag == rcall->tag) {
				req = rreq;
				if (req->flush != Flushing)
					list_del(&req->req_list);
				break;
			}
		}
		spin_unlock(&m->lock);

		if (req) {
			req->rcall = rcall;
			process_request(m, req);

			if (req->flush != Flushing) {
				if (req->cb)
					(*req->cb) (req, req->cba);
				else
					kfree(req->rcall);

				wake_up(&m->equeue);
			}
		} else {
			if (err >= 0 && rcall->id != P9_RFLUSH)
				P9_DPRINTK(P9_DEBUG_ERROR,
				  "unexpected response mux %p id %d tag %d\n",
				  m, rcall->id, rcall->tag);
			kfree(rcall);
		}
	}

	if (!list_empty(&m->req_list)) {
		if (test_and_clear_bit(Rpending, &m->wsched))
			n = POLLIN;
		else
			n = m->trans->poll(m->trans, NULL);

		if (n & POLLIN) {
			P9_DPRINTK(P9_DEBUG_MUX, "schedule read work %p\n", m);
			queue_work(p9_mux_wq, &m->rq);
		} else
			clear_bit(Rworksched, &m->wsched);
	} else
		clear_bit(Rworksched, &m->wsched);

	return;

error:
	p9_conn_cancel(m, err);
	clear_bit(Rworksched, &m->wsched);
}

/**
 * p9_send_request - send 9P request
 * The function can sleep until the request is scheduled for sending.
 * The function can be interrupted. Return from the function is not
 * a guarantee that the request is sent successfully. Can return errors
 * that can be retrieved by PTR_ERR macros.
 *
 * @m: mux data
 * @tc: request to be sent
 * @cb: callback function to call when response is received
 * @cba: parameter to pass to the callback function
 */
static struct p9_req *p9_send_request(struct p9_conn *m,
					  struct p9_fcall *tc,
					  p9_conn_req_callback cb, void *cba)
{
	int n;
	struct p9_req *req;

	P9_DPRINTK(P9_DEBUG_MUX, "mux %p task %p tcall %p id %d\n", m, current,
		tc, tc->id);
	if (m->err < 0)
		return ERR_PTR(m->err);

	req = kmalloc(sizeof(struct p9_req), GFP_KERNEL);
	if (!req)
		return ERR_PTR(-ENOMEM);

	if (tc->id == P9_TVERSION)
		n = P9_NOTAG;
	else
		n = p9_mux_get_tag(m);

	if (n < 0)
		return ERR_PTR(-ENOMEM);

	p9_set_tag(tc, n);

#ifdef CONFIG_NET_9P_DEBUG
	if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
		char buf[150];

		p9_printfcall(buf, sizeof(buf), tc, *m->extended);
		printk(KERN_NOTICE "<<< %p %s\n", m, buf);
	}
#endif

	spin_lock_init(&req->lock);
	req->tag = n;
	req->tcall = tc;
	req->rcall = NULL;
	req->err = 0;
	req->cb = cb;
	req->cba = cba;
	req->flush = None;

	spin_lock(&m->lock);
	list_add_tail(&req->req_list, &m->unsent_req_list);
	spin_unlock(&m->lock);

	if (test_and_clear_bit(Wpending, &m->wsched))
		n = POLLOUT;
	else
		n = m->trans->poll(m->trans, NULL);

	if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
		queue_work(p9_mux_wq, &m->wq);

	return req;
}

static void p9_mux_free_request(struct p9_conn *m, struct p9_req *req)
{
	p9_mux_put_tag(m, req->tag);
	kfree(req);
}

static void p9_mux_flush_cb(struct p9_req *freq, void *a)
{
	p9_conn_req_callback cb;
	int tag;
	struct p9_conn *m;
	struct p9_req *req, *rreq, *rptr;

	m = a;
	P9_DPRINTK(P9_DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m,
		freq->tcall, freq->rcall, freq->err,
		freq->tcall->params.tflush.oldtag);

	spin_lock(&m->lock);
	cb = NULL;
	tag = freq->tcall->params.tflush.oldtag;
	req = NULL;
	list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
		if (rreq->tag == tag) {
			req = rreq;
			list_del(&req->req_list);
			break;
		}
	}
	spin_unlock(&m->lock);

	if (req) {
		spin_lock(&req->lock);
		req->flush = Flushed;
		spin_unlock(&req->lock);

		if (req->cb)
			(*req->cb) (req, req->cba);
		else
			kfree(req->rcall);

		wake_up(&m->equeue);
	}

	kfree(freq->tcall);
	kfree(freq->rcall);
	p9_mux_free_request(m, freq);
}

static int
p9_mux_flush_request(struct p9_conn *m, struct p9_req *req)
{
	struct p9_fcall *fc;
	struct p9_req *rreq, *rptr;

	P9_DPRINTK(P9_DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);

	/* if a response was received for a request, do nothing */
	spin_lock(&req->lock);
	if (req->rcall || req->err) {
		spin_unlock(&req->lock);
		P9_DPRINTK(P9_DEBUG_MUX,
			"mux %p req %p response already received\n", m, req);
		return 0;
	}

	req->flush = Flushing;
	spin_unlock(&req->lock);

	spin_lock(&m->lock);
	/* if the request is not sent yet, just remove it from the list */
	list_for_each_entry_safe(rreq, rptr, &m->unsent_req_list, req_list) {
		if (rreq->tag == req->tag) {
			P9_DPRINTK(P9_DEBUG_MUX,
			   "mux %p req %p request is not sent yet\n", m, req);
			list_del(&rreq->req_list);
			req->flush = Flushed;
			spin_unlock(&m->lock);
			if (req->cb)
				(*req->cb) (req, req->cba);
			return 0;
		}
	}
	spin_unlock(&m->lock);

	clear_thread_flag(TIF_SIGPENDING);
	fc = p9_create_tflush(req->tag);
	p9_send_request(m, fc, p9_mux_flush_cb, m);
	return 1;
}

static void
p9_conn_rpc_cb(struct p9_req *req, void *a)
{
	struct p9_mux_rpc *r;

	P9_DPRINTK(P9_DEBUG_MUX, "req %p r %p\n", req, a);
	r = a;
	r->rcall = req->rcall;
	r->err = req->err;

	if (req->flush != None && !req->err)
		r->err = -ERESTARTSYS;

	wake_up(&r->wqueue);
}

/**
 * p9_mux_rpc - sends 9P request and waits until a response is available.
 *	The function can be interrupted.
 * @m: mux data
 * @tc: request to be sent
 * @rc: pointer where a pointer to the response is stored
 */
int
p9_conn_rpc(struct p9_conn *m, struct p9_fcall *tc,
	     struct p9_fcall **rc)
{
	int err, sigpending;
	unsigned long flags;
	struct p9_req *req;
	struct p9_mux_rpc r;

	r.err = 0;
	r.tcall = tc;
	r.rcall = NULL;
	r.m = m;
	init_waitqueue_head(&r.wqueue);

	if (rc)
		*rc = NULL;

	sigpending = 0;
	if (signal_pending(current)) {
		sigpending = 1;
		clear_thread_flag(TIF_SIGPENDING);
	}

	req = p9_send_request(m, tc, p9_conn_rpc_cb, &r);
	if (IS_ERR(req)) {
		err = PTR_ERR(req);
		P9_DPRINTK(P9_DEBUG_MUX, "error %d\n", err);
		return err;
	}

	err = wait_event_interruptible(r.wqueue, r.rcall != NULL || r.err < 0);
	if (r.err < 0)
		err = r.err;

	if (err == -ERESTARTSYS && m->trans->status == Connected
							&& m->err == 0) {
		if (p9_mux_flush_request(m, req)) {
			/* wait until we get response of the flush message */
			do {
				clear_thread_flag(TIF_SIGPENDING);
				err = wait_event_interruptible(r.wqueue,
					r.rcall || r.err);
			} while (!r.rcall && !r.err && err == -ERESTARTSYS &&
				m->trans->status == Connected && !m->err);

			err = -ERESTARTSYS;
		}
		sigpending = 1;
	}

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

	if (rc)
		*rc = r.rcall;
	else
		kfree(r.rcall);

	p9_mux_free_request(m, req);
	if (err > 0)
		err = -EIO;

	return err;
}
EXPORT_SYMBOL(p9_conn_rpc);

#ifdef P9_NONBLOCK
/**
 * p9_conn_rpcnb - sends 9P request without waiting for response.
 * @m: mux data
 * @tc: request to be sent
 * @cb: callback function to be called when response arrives
 * @cba: value to pass to the callback function
 */
int p9_conn_rpcnb(struct p9_conn *m, struct p9_fcall *tc,
		   p9_conn_req_callback cb, void *a)
{
	int err;
	struct p9_req *req;

	req = p9_send_request(m, tc, cb, a);
	if (IS_ERR(req)) {
		err = PTR_ERR(req);
		P9_DPRINTK(P9_DEBUG_MUX, "error %d\n", err);
		return PTR_ERR(req);
	}

	P9_DPRINTK(P9_DEBUG_MUX, "mux %p tc %p tag %d\n", m, tc, req->tag);
	return 0;
}
EXPORT_SYMBOL(p9_conn_rpcnb);
#endif /* P9_NONBLOCK */

/**
 * p9_conn_cancel - cancel all pending requests with error
 * @m: mux data
 * @err: error code
 */
void p9_conn_cancel(struct p9_conn *m, int err)
{
	struct p9_req *req, *rtmp;
	LIST_HEAD(cancel_list);

	P9_DPRINTK(P9_DEBUG_ERROR, "mux %p err %d\n", m, err);
	m->err = err;
	spin_lock(&m->lock);
	list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
		list_move(&req->req_list, &cancel_list);
	}
	list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
		list_move(&req->req_list, &cancel_list);
	}
	spin_unlock(&m->lock);

	list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
		list_del(&req->req_list);
		if (!req->err)
			req->err = err;

		if (req->cb)
			(*req->cb) (req, req->cba);
		else
			kfree(req->rcall);
	}

	wake_up(&m->equeue);
}
EXPORT_SYMBOL(p9_conn_cancel);

static u16 p9_mux_get_tag(struct p9_conn *m)
{
	int tag;

	tag = p9_idpool_get(m->tagpool);
	if (tag < 0)
		return P9_NOTAG;
	else
		return (u16) tag;
}

static void p9_mux_put_tag(struct p9_conn *m, u16 tag)
{
	if (tag != P9_NOTAG && p9_idpool_check(tag, m->tagpool))
		p9_idpool_put(tag, m->tagpool);
}