rxrpc: Don't expose skbs to in-kernel users [ver #2]

Don't expose skbs to in-kernel users, such as the AFS filesystem, but
instead provide a notification hook the indicates that a call needs
attention and another that indicates that there's a new call to be
collected.

This makes the following possibilities more achievable:

 (1) Call refcounting can be made simpler if skbs don't hold refs to calls.

 (2) skbs referring to non-data events will be able to be freed much sooner
     rather than being queued for AFS to pick up as rxrpc_kernel_recv_data
     will be able to consult the call state.

 (3) We can shortcut the receive phase when a call is remotely aborted
     because we don't have to go through all the packets to get to the one
     cancelling the operation.

 (4) It makes it easier to do encryption/decryption directly between AFS's
     buffers and sk_buffs.

 (5) Encryption/decryption can more easily be done in the AFS's thread
     contexts - usually that of the userspace process that issued a syscall
     - rather than in one of rxrpc's background threads on a workqueue.

 (6) AFS will be able to wait synchronously on a call inside AF_RXRPC.

To make this work, the following interface function has been added:

     int rxrpc_kernel_recv_data(
		struct socket *sock, struct rxrpc_call *call,
		void *buffer, size_t bufsize, size_t *_offset,
		bool want_more, u32 *_abort_code);

This is the recvmsg equivalent.  It allows the caller to find out about the
state of a specific call and to transfer received data into a buffer
piecemeal.

afs_extract_data() and rxrpc_kernel_recv_data() now do all the extraction
logic between them.  They don't wait synchronously yet because the socket
lock needs to be dealt with.

Five interface functions have been removed:

	rxrpc_kernel_is_data_last()
    	rxrpc_kernel_get_abort_code()
    	rxrpc_kernel_get_error_number()
    	rxrpc_kernel_free_skb()
    	rxrpc_kernel_data_consumed()

As a temporary hack, sk_buffs going to an in-kernel call are queued on the
rxrpc_call struct (->knlrecv_queue) rather than being handed over to the
in-kernel user.  To process the queue internally, a temporary function,
temp_deliver_data() has been added.  This will be replaced with common code
between the rxrpc_recvmsg() path and the kernel_rxrpc_recv_data() path in a
future patch.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 158 insertions, 281 deletions

diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index 7b0d189..244896b 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -19,31 +19,31 @@
 struct socket *afs_socket; /* my RxRPC socket */
 static struct workqueue_struct *afs_async_calls;
 static atomic_t afs_outstanding_calls;
-static atomic_t afs_outstanding_skbs;
 
-static void afs_wake_up_call_waiter(struct afs_call *);
+static void afs_free_call(struct afs_call *);
+static void afs_wake_up_call_waiter(struct sock *, struct rxrpc_call *, unsigned long);
 static int afs_wait_for_call_to_complete(struct afs_call *);
-static void afs_wake_up_async_call(struct afs_call *);
+static void afs_wake_up_async_call(struct sock *, struct rxrpc_call *, unsigned long);
 static int afs_dont_wait_for_call_to_complete(struct afs_call *);
-static void afs_process_async_call(struct afs_call *);
-static void afs_rx_interceptor(struct sock *, unsigned long, struct sk_buff *);
-static int afs_deliver_cm_op_id(struct afs_call *, struct sk_buff *, bool);
+static void afs_process_async_call(struct work_struct *);
+static void afs_rx_new_call(struct sock *);
+static int afs_deliver_cm_op_id(struct afs_call *);
 
 /* synchronous call management */
 const struct afs_wait_mode afs_sync_call = {
-	.rx_wakeup	= afs_wake_up_call_waiter,
+	.notify_rx	= afs_wake_up_call_waiter,
 	.wait		= afs_wait_for_call_to_complete,
 };
 
 /* asynchronous call management */
 const struct afs_wait_mode afs_async_call = {
-	.rx_wakeup	= afs_wake_up_async_call,
+	.notify_rx	= afs_wake_up_async_call,
 	.wait		= afs_dont_wait_for_call_to_complete,
 };
 
 /* asynchronous incoming call management */
 static const struct afs_wait_mode afs_async_incoming_call = {
-	.rx_wakeup	= afs_wake_up_async_call,
+	.notify_rx	= afs_wake_up_async_call,
 };
 
 /* asynchronous incoming call initial processing */
@@ -55,16 +55,8 @@ static const struct afs_call_type afs_RXCMxxxx = {
 
 static void afs_collect_incoming_call(struct work_struct *);
 
-static struct sk_buff_head afs_incoming_calls;
 static DECLARE_WORK(afs_collect_incoming_call_work, afs_collect_incoming_call);
 
-static void afs_async_workfn(struct work_struct *work)
-{
-	struct afs_call *call = container_of(work, struct afs_call, async_work);
-
-	call->async_workfn(call);
-}
-
 static int afs_wait_atomic_t(atomic_t *p)
 {
 	schedule();
@@ -83,8 +75,6 @@ int afs_open_socket(void)
 
 	_enter("");
 
-	skb_queue_head_init(&afs_incoming_calls);
-
 	ret = -ENOMEM;
 	afs_async_calls = create_singlethread_workqueue("kafsd");
 	if (!afs_async_calls)
@@ -110,12 +100,12 @@ int afs_open_socket(void)
 	if (ret < 0)
 		goto error_2;
 
+	rxrpc_kernel_new_call_notification(socket, afs_rx_new_call);
+
 	ret = kernel_listen(socket, INT_MAX);
 	if (ret < 0)
 		goto error_2;
 
-	rxrpc_kernel_intercept_rx_messages(socket, afs_rx_interceptor);
-
 	afs_socket = socket;
 	_leave(" = 0");
 	return 0;
@@ -136,52 +126,20 @@ void afs_close_socket(void)
 {
 	_enter("");
 
+	_debug("outstanding %u", atomic_read(&afs_outstanding_calls));
 	wait_on_atomic_t(&afs_outstanding_calls, afs_wait_atomic_t,
 			 TASK_UNINTERRUPTIBLE);
 	_debug("no outstanding calls");
 
+	flush_workqueue(afs_async_calls);
 	sock_release(afs_socket);
 
 	_debug("dework");
 	destroy_workqueue(afs_async_calls);
-
-	ASSERTCMP(atomic_read(&afs_outstanding_skbs), ==, 0);
 	_leave("");
 }
 
 /*
- * Note that the data in a socket buffer is now consumed.
- */
-void afs_data_consumed(struct afs_call *call, struct sk_buff *skb)
-{
-	if (!skb) {
-		_debug("DLVR NULL [%d]", atomic_read(&afs_outstanding_skbs));
-		dump_stack();
-	} else {
-		_debug("DLVR %p{%u} [%d]",
-		       skb, skb->mark, atomic_read(&afs_outstanding_skbs));
-		rxrpc_kernel_data_consumed(call->rxcall, skb);
-	}
-}
-
-/*
- * free a socket buffer
- */
-static void afs_free_skb(struct sk_buff *skb)
-{
-	if (!skb) {
-		_debug("FREE NULL [%d]", atomic_read(&afs_outstanding_skbs));
-		dump_stack();
-	} else {
-		_debug("FREE %p{%u} [%d]",
-		       skb, skb->mark, atomic_read(&afs_outstanding_skbs));
-		if (atomic_dec_return(&afs_outstanding_skbs) == -1)
-			BUG();
-		rxrpc_kernel_free_skb(skb);
-	}
-}
-
-/*
  * free a call
  */
 static void afs_free_call(struct afs_call *call)
@@ -191,7 +149,6 @@ static void afs_free_call(struct afs_call *call)
 
 	ASSERTCMP(call->rxcall, ==, NULL);
 	ASSERT(!work_pending(&call->async_work));
-	ASSERT(skb_queue_empty(&call->rx_queue));
 	ASSERT(call->type->name != NULL);
 
 	kfree(call->request);
@@ -227,7 +184,7 @@ static void afs_end_call(struct afs_call *call)
  * allocate a call with flat request and reply buffers
  */
 struct afs_call *afs_alloc_flat_call(const struct afs_call_type *type,
-				     size_t request_size, size_t reply_size)
+				     size_t request_size, size_t reply_max)
 {
 	struct afs_call *call;
 
@@ -241,7 +198,7 @@ struct afs_call *afs_alloc_flat_call(const struct afs_call_type *type,
 
 	call->type = type;
 	call->request_size = request_size;
-	call->reply_max = reply_size;
+	call->reply_max = reply_max;
 
 	if (request_size) {
 		call->request = kmalloc(request_size, GFP_NOFS);
@@ -249,14 +206,13 @@ struct afs_call *afs_alloc_flat_call(const struct afs_call_type *type,
 			goto nomem_free;
 	}
 
-	if (reply_size) {
-		call->buffer = kmalloc(reply_size, GFP_NOFS);
+	if (reply_max) {
+		call->buffer = kmalloc(reply_max, GFP_NOFS);
 		if (!call->buffer)
 			goto nomem_free;
 	}
 
 	init_waitqueue_head(&call->waitq);
-	skb_queue_head_init(&call->rx_queue);
 	return call;
 
 nomem_free:
@@ -354,7 +310,6 @@ int afs_make_call(struct in_addr *addr, struct afs_call *call, gfp_t gfp,
 	struct msghdr msg;
 	struct kvec iov[1];
 	int ret;
-	struct sk_buff *skb;
 
 	_enter("%x,{%d},", addr->s_addr, ntohs(call->port));
 
@@ -366,8 +321,7 @@ int afs_make_call(struct in_addr *addr, struct afs_call *call, gfp_t gfp,
 	       atomic_read(&afs_outstanding_calls));
 
 	call->wait_mode = wait_mode;
-	call->async_workfn = afs_process_async_call;
-	INIT_WORK(&call->async_work, afs_async_workfn);
+	INIT_WORK(&call->async_work, afs_process_async_call);
 
 	memset(&srx, 0, sizeof(srx));
 	srx.srx_family = AF_RXRPC;
@@ -380,7 +334,8 @@ int afs_make_call(struct in_addr *addr, struct afs_call *call, gfp_t gfp,
 
 	/* create a call */
 	rxcall = rxrpc_kernel_begin_call(afs_socket, &srx, call->key,
-					 (unsigned long) call, gfp);
+					 (unsigned long) call, gfp,
+					 wait_mode->notify_rx);
 	call->key = NULL;
 	if (IS_ERR(rxcall)) {
 		ret = PTR_ERR(rxcall);
@@ -423,8 +378,6 @@ int afs_make_call(struct in_addr *addr, struct afs_call *call, gfp_t gfp,
 
 error_do_abort:
 	rxrpc_kernel_abort_call(afs_socket, rxcall, RX_USER_ABORT);
-	while ((skb = skb_dequeue(&call->rx_queue)))
-		afs_free_skb(skb);
 error_kill_call:
 	afs_end_call(call);
 	_leave(" = %d", ret);
@@ -432,141 +385,77 @@ error_kill_call:
 }
 
 /*
- * Handles intercepted messages that were arriving in the socket's Rx queue.
- *
- * Called from the AF_RXRPC call processor in waitqueue process context.  For
- * each call, it is guaranteed this will be called in order of packet to be
- * delivered.
- */
-static void afs_rx_interceptor(struct sock *sk, unsigned long user_call_ID,
-			       struct sk_buff *skb)
-{
-	struct afs_call *call = (struct afs_call *) user_call_ID;
-
-	_enter("%p,,%u", call, skb->mark);
-
-	_debug("ICPT %p{%u} [%d]",
-	       skb, skb->mark, atomic_read(&afs_outstanding_skbs));
-
-	ASSERTCMP(sk, ==, afs_socket->sk);
-	atomic_inc(&afs_outstanding_skbs);
-
-	if (!call) {
-		/* its an incoming call for our callback service */
-		skb_queue_tail(&afs_incoming_calls, skb);
-		queue_work(afs_wq, &afs_collect_incoming_call_work);
-	} else {
-		/* route the messages directly to the appropriate call */
-		skb_queue_tail(&call->rx_queue, skb);
-		call->wait_mode->rx_wakeup(call);
-	}
-
-	_leave("");
-}
-
-/*
  * deliver messages to a call
  */
 static void afs_deliver_to_call(struct afs_call *call)
 {
-	struct sk_buff *skb;
-	bool last;
 	u32 abort_code;
 	int ret;
 
-	_enter("");
-
-	while ((call->state == AFS_CALL_AWAIT_REPLY ||
-		call->state == AFS_CALL_AWAIT_OP_ID ||
-		call->state == AFS_CALL_AWAIT_REQUEST ||
-		call->state == AFS_CALL_AWAIT_ACK) &&
-	       (skb = skb_dequeue(&call->rx_queue))) {
-		switch (skb->mark) {
-		case RXRPC_SKB_MARK_DATA:
-			_debug("Rcv DATA");
-			last = rxrpc_kernel_is_data_last(skb);
-			ret = call->type->deliver(call, skb, last);
-			switch (ret) {
-			case -EAGAIN:
-				if (last) {
-					_debug("short data");
-					goto unmarshal_error;
-				}
-				break;
-			case 0:
-				ASSERT(last);
-				if (call->state == AFS_CALL_AWAIT_REPLY)
-					call->state = AFS_CALL_COMPLETE;
-				break;
-			case -ENOTCONN:
-				abort_code = RX_CALL_DEAD;
-				goto do_abort;
-			case -ENOTSUPP:
-				abort_code = RX_INVALID_OPERATION;
-				goto do_abort;
-			default:
-			unmarshal_error:
-				abort_code = RXGEN_CC_UNMARSHAL;
-				if (call->state != AFS_CALL_AWAIT_REPLY)
-					abort_code = RXGEN_SS_UNMARSHAL;
-			do_abort:
-				rxrpc_kernel_abort_call(afs_socket,
-							call->rxcall,
-							abort_code);
-				call->error = ret;
-				call->state = AFS_CALL_ERROR;
-				break;
+	_enter("%s", call->type->name);
+
+	while (call->state == AFS_CALL_AWAIT_REPLY ||
+	       call->state == AFS_CALL_AWAIT_OP_ID ||
+	       call->state == AFS_CALL_AWAIT_REQUEST ||
+	       call->state == AFS_CALL_AWAIT_ACK
+	       ) {
+		if (call->state == AFS_CALL_AWAIT_ACK) {
+			size_t offset = 0;
+			ret = rxrpc_kernel_recv_data(afs_socket, call->rxcall,
+						     NULL, 0, &offset, false,
+						     &call->abort_code);
+			if (ret == -EINPROGRESS || ret == -EAGAIN)
+				return;
+			if (ret == 1) {
+				call->state = AFS_CALL_COMPLETE;
+				goto done;
 			}
-			break;
-		case RXRPC_SKB_MARK_FINAL_ACK:
-			_debug("Rcv ACK");
-			call->state = AFS_CALL_COMPLETE;
-			break;
-		case RXRPC_SKB_MARK_BUSY:
-			_debug("Rcv BUSY");
-			call->error = -EBUSY;
-			call->state = AFS_CALL_BUSY;
-			break;
-		case RXRPC_SKB_MARK_REMOTE_ABORT:
-			abort_code = rxrpc_kernel_get_abort_code(skb);
-			call->error = call->type->abort_to_error(abort_code);
-			call->state = AFS_CALL_ABORTED;
-			_debug("Rcv ABORT %u -> %d", abort_code, call->error);
-			break;
-		case RXRPC_SKB_MARK_LOCAL_ABORT:
-			abort_code = rxrpc_kernel_get_abort_code(skb);
-			call->error = call->type->abort_to_error(abort_code);
-			call->state = AFS_CALL_ABORTED;
-			_debug("Loc ABORT %u -> %d", abort_code, call->error);
-			break;
-		case RXRPC_SKB_MARK_NET_ERROR:
-			call->error = -rxrpc_kernel_get_error_number(skb);
-			call->state = AFS_CALL_ERROR;
-			_debug("Rcv NET ERROR %d", call->error);
-			break;
-		case RXRPC_SKB_MARK_LOCAL_ERROR:
-			call->error = -rxrpc_kernel_get_error_number(skb);
-			call->state = AFS_CALL_ERROR;
-			_debug("Rcv LOCAL ERROR %d", call->error);
-			break;
-		default:
-			BUG();
-			break;
+			return;
 		}
 
-		afs_free_skb(skb);
-	}
-
-	/* make sure the queue is empty if the call is done with (we might have
-	 * aborted the call early because of an unmarshalling error) */
-	if (call->state >= AFS_CALL_COMPLETE) {
-		while ((skb = skb_dequeue(&call->rx_queue)))
-			afs_free_skb(skb);
-		if (call->incoming)
-			afs_end_call(call);
+		ret = call->type->deliver(call);
+		switch (ret) {
+		case 0:
+			if (call->state == AFS_CALL_AWAIT_REPLY)
+				call->state = AFS_CALL_COMPLETE;
+			goto done;
+		case -EINPROGRESS:
+		case -EAGAIN:
+			goto out;
+		case -ENOTCONN:
+			abort_code = RX_CALL_DEAD;
+			rxrpc_kernel_abort_call(afs_socket, call->rxcall,
+						abort_code);
+			goto do_abort;
+		case -ENOTSUPP:
+			abort_code = RX_INVALID_OPERATION;
+			rxrpc_kernel_abort_call(afs_socket, call->rxcall,
+						abort_code);
+			goto do_abort;
+		case -ENODATA:
+		case -EBADMSG:
+		case -EMSGSIZE:
+		default:
+			abort_code = RXGEN_CC_UNMARSHAL;
+			if (call->state != AFS_CALL_AWAIT_REPLY)
+				abort_code = RXGEN_SS_UNMARSHAL;
+			rxrpc_kernel_abort_call(afs_socket, call->rxcall,
+						abort_code);
+			goto do_abort;
+		}
 	}
 
+done:
+	if (call->state == AFS_CALL_COMPLETE && call->incoming)
+		afs_end_call(call);
+out:
 	_leave("");
+	return;
+
+do_abort:
+	call->error = ret;
+	call->state = AFS_CALL_COMPLETE;
+	goto done;
 }
 
 /*
@@ -574,7 +463,6 @@ static void afs_deliver_to_call(struct afs_call *call)
  */
 static int afs_wait_for_call_to_complete(struct afs_call *call)
 {
-	struct sk_buff *skb;
 	int ret;
 
 	DECLARE_WAITQUEUE(myself, current);
@@ -586,14 +474,15 @@ static int afs_wait_for_call_to_complete(struct afs_call *call)
 		set_current_state(TASK_INTERRUPTIBLE);
 
 		/* deliver any messages that are in the queue */
-		if (!skb_queue_empty(&call->rx_queue)) {
+		if (call->state < AFS_CALL_COMPLETE && call->need_attention) {
+			call->need_attention = false;
 			__set_current_state(TASK_RUNNING);
 			afs_deliver_to_call(call);
 			continue;
 		}
 
 		ret = call->error;
-		if (call->state >= AFS_CALL_COMPLETE)
+		if (call->state == AFS_CALL_COMPLETE)
 			break;
 		ret = -EINTR;
 		if (signal_pending(current))
@@ -607,9 +496,8 @@ static int afs_wait_for_call_to_complete(struct afs_call *call)
 	/* kill the call */
 	if (call->state < AFS_CALL_COMPLETE) {
 		_debug("call incomplete");
-		rxrpc_kernel_abort_call(afs_socket, call->rxcall, RX_CALL_DEAD);
-		while ((skb = skb_dequeue(&call->rx_queue)))
-			afs_free_skb(skb);
+		rxrpc_kernel_abort_call(afs_socket, call->rxcall,
+					RX_CALL_DEAD);
 	}
 
 	_debug("call complete");
@@ -621,17 +509,24 @@ static int afs_wait_for_call_to_complete(struct afs_call *call)
 /*
  * wake up a waiting call
  */
-static void afs_wake_up_call_waiter(struct afs_call *call)
+static void afs_wake_up_call_waiter(struct sock *sk, struct rxrpc_call *rxcall,
+				    unsigned long call_user_ID)
 {
+	struct afs_call *call = (struct afs_call *)call_user_ID;
+
+	call->need_attention = true;
 	wake_up(&call->waitq);
 }
 
 /*
  * wake up an asynchronous call
  */
-static void afs_wake_up_async_call(struct afs_call *call)
+static void afs_wake_up_async_call(struct sock *sk, struct rxrpc_call *rxcall,
+				   unsigned long call_user_ID)
 {
-	_enter("");
+	struct afs_call *call = (struct afs_call *)call_user_ID;
+
+	call->need_attention = true;
 	queue_work(afs_async_calls, &call->async_work);
 }
 
@@ -649,8 +544,10 @@ static int afs_dont_wait_for_call_to_complete(struct afs_call *call)
 /*
  * delete an asynchronous call
  */
-static void afs_delete_async_call(struct afs_call *call)
+static void afs_delete_async_call(struct work_struct *work)
 {
+	struct afs_call *call = container_of(work, struct afs_call, async_work);
+
 	_enter("");
 
 	afs_free_call(call);
@@ -660,17 +557,19 @@ static void afs_delete_async_call(struct afs_call *call)
 
 /*
  * perform processing on an asynchronous call
- * - on a multiple-thread workqueue this work item may try to run on several
- *   CPUs at the same time
  */
-static void afs_process_async_call(struct afs_call *call)
+static void afs_process_async_call(struct work_struct *work)
 {
+	struct afs_call *call = container_of(work, struct afs_call, async_work);
+
 	_enter("");
 
-	if (!skb_queue_empty(&call->rx_queue))
+	if (call->state < AFS_CALL_COMPLETE && call->need_attention) {
+		call->need_attention = false;
 		afs_deliver_to_call(call);
+	}
 
-	if (call->state >= AFS_CALL_COMPLETE && call->wait_mode) {
+	if (call->state == AFS_CALL_COMPLETE && call->wait_mode) {
 		if (call->wait_mode->async_complete)
 			call->wait_mode->async_complete(call->reply,
 							call->error);
@@ -681,7 +580,7 @@ static void afs_process_async_call(struct afs_call *call)
 
 		/* we can't just delete the call because the work item may be
 		 * queued */
-		call->async_workfn = afs_delete_async_call;
+		call->async_work.func = afs_delete_async_call;
 		queue_work(afs_async_calls, &call->async_work);
 	}
 
@@ -689,52 +588,16 @@ static void afs_process_async_call(struct afs_call *call)
 }
 
 /*
- * Empty a socket buffer into a flat reply buffer.
- */
-int afs_transfer_reply(struct afs_call *call, struct sk_buff *skb, bool last)
-{
-	size_t len = skb->len;
-
-	if (len > call->reply_max - call->reply_size) {
-		_leave(" = -EBADMSG [%zu > %u]",
-		       len, call->reply_max - call->reply_size);
-		return -EBADMSG;
-	}
-
-	if (len > 0) {
-		if (skb_copy_bits(skb, 0, call->buffer + call->reply_size,
-				  len) < 0)
-			BUG();
-		call->reply_size += len;
-	}
-
-	afs_data_consumed(call, skb);
-	if (!last)
-		return -EAGAIN;
-
-	if (call->reply_size != call->reply_max) {
-		_leave(" = -EBADMSG [%u != %u]",
-		       call->reply_size, call->reply_max);
-		return -EBADMSG;
-	}
-	return 0;
-}
-
-/*
  * accept the backlog of incoming calls
  */
 static void afs_collect_incoming_call(struct work_struct *work)
 {
 	struct rxrpc_call *rxcall;
 	struct afs_call *call = NULL;
-	struct sk_buff *skb;
-
-	while ((skb = skb_dequeue(&afs_incoming_calls))) {
-		_debug("new call");
 
-		/* don't need the notification */
-		afs_free_skb(skb);
+	_enter("");
 
+	do {
 		if (!call) {
 			call = kzalloc(sizeof(struct afs_call), GFP_KERNEL);
 			if (!call) {
@@ -742,12 +605,10 @@ static void afs_collect_incoming_call(struct work_struct *work)
 				return;
 			}
 
-			call->async_workfn = afs_process_async_call;
-			INIT_WORK(&call->async_work, afs_async_workfn);
+			INIT_WORK(&call->async_work, afs_process_async_call);
 			call->wait_mode = &afs_async_incoming_call;
 			call->type = &afs_RXCMxxxx;
 			init_waitqueue_head(&call->waitq);
-			skb_queue_head_init(&call->rx_queue);
 			call->state = AFS_CALL_AWAIT_OP_ID;
 
 			_debug("CALL %p{%s} [%d]",
@@ -757,46 +618,47 @@ static void afs_collect_incoming_call(struct work_struct *work)
 		}
 
 		rxcall = rxrpc_kernel_accept_call(afs_socket,
-						  (unsigned long) call);
+						  (unsigned long)call,
+						  afs_wake_up_async_call);
 		if (!IS_ERR(rxcall)) {
 			call->rxcall = rxcall;
+			call->need_attention = true;
+			queue_work(afs_async_calls, &call->async_work);
 			call = NULL;
 		}
-	}
+	} while (!call);
 
 	if (call)
 		afs_free_call(call);
 }
 
 /*
+ * Notification of an incoming call.
+ */
+static void afs_rx_new_call(struct sock *sk)
+{
+	queue_work(afs_wq, &afs_collect_incoming_call_work);
+}
+
+/*
  * Grab the operation ID from an incoming cache manager call.  The socket
  * buffer is discarded on error or if we don't yet have sufficient data.
  */
-static int afs_deliver_cm_op_id(struct afs_call *call, struct sk_buff *skb,
-				bool last)
+static int afs_deliver_cm_op_id(struct afs_call *call)
 {
-	size_t len = skb->len;
-	void *oibuf = (void *) &call->operation_ID;
+	int ret;
 
-	_enter("{%u},{%zu},%d", call->offset, len, last);
+	_enter("{%zu}", call->offset);
 
 	ASSERTCMP(call->offset, <, 4);
 
 	/* the operation ID forms the first four bytes of the request data */
-	len = min_t(size_t, len, 4 - call->offset);
-	if (skb_copy_bits(skb, 0, oibuf + call->offset, len) < 0)
-		BUG();
-	if (!pskb_pull(skb, len))
-		BUG();
-	call->offset += len;
-
-	if (call->offset < 4) {
-		afs_data_consumed(call, skb);
-		_leave(" = -EAGAIN");
-		return -EAGAIN;
-	}
+	ret = afs_extract_data(call, &call->operation_ID, 4, true);
+	if (ret < 0)
+		return ret;
 
 	call->state = AFS_CALL_AWAIT_REQUEST;
+	call->offset = 0;
 
 	/* ask the cache manager to route the call (it'll change the call type
 	 * if successful) */
@@ -805,7 +667,7 @@ static int afs_deliver_cm_op_id(struct afs_call *call, struct sk_buff *skb,
 
 	/* pass responsibility for the remainer of this message off to the
 	 * cache manager op */
-	return call->type->deliver(call, skb, last);
+	return call->type->deliver(call);
 }
 
 /*
@@ -881,25 +743,40 @@ void afs_send_simple_reply(struct afs_call *call, const void *buf, size_t len)
 /*
  * Extract a piece of data from the received data socket buffers.
  */
-int afs_extract_data(struct afs_call *call, struct sk_buff *skb,
-		     bool last, void *buf, size_t count)
+int afs_extract_data(struct afs_call *call, void *buf, size_t count,
+		     bool want_more)
 {
-	size_t len = skb->len;
+	int ret;
 
-	_enter("{%u},{%zu},%d,,%zu", call->offset, len, last, count);
+	_enter("{%s,%zu},,%zu,%d",
+	       call->type->name, call->offset, count, want_more);
 
-	ASSERTCMP(call->offset, <, count);
+	ASSERTCMP(call->offset, <=, count);
 
-	len = min_t(size_t, len, count - call->offset);
-	if (skb_copy_bits(skb, 0, buf + call->offset, len) < 0 ||
-	    !pskb_pull(skb, len))
-		BUG();
-	call->offset += len;
+	ret = rxrpc_kernel_recv_data(afs_socket, call->rxcall,
+				     buf, count, &call->offset,
+				     want_more, &call->abort_code);
+	if (ret == 0 || ret == -EAGAIN)
+		return ret;
 
-	if (call->offset < count) {
-		afs_data_consumed(call, skb);
-		_leave(" = -EAGAIN");
-		return -EAGAIN;
+	if (ret == 1) {
+		switch (call->state) {
+		case AFS_CALL_AWAIT_REPLY:
+			call->state = AFS_CALL_COMPLETE;
+			break;
+		case AFS_CALL_AWAIT_REQUEST:
+			call->state = AFS_CALL_REPLYING;
+			break;
+		default:
+			break;
+		}
+		return 0;
 	}
-	return 0;
+
+	if (ret == -ECONNABORTED)
+		call->error = call->type->abort_to_error(call->abort_code);
+	else
+		call->error = ret;
+	call->state = AFS_CALL_COMPLETE;
+	return ret;
 }