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linux-next/fs/afs/rxrpc.c
David Howells dc44b3a09a rxrpc: Differentiate local and remote abort codes in structs
In the rxrpc_connection and rxrpc_call structs, there's one field to hold
the abort code, no matter whether that value was generated locally to be
sent or was received from the peer via an abort packet.

Split the abort code fields in two for cleanliness sake and add an error
field to hold the Linux error number to the rxrpc_call struct too
(sometimes this is generated in a context where we can't return it to
userspace directly).

Furthermore, add a skb mark to indicate a packet that caused a local abort
to be generated so that recvmsg() can pick up the correct abort code.  A
future addition will need to be to indicate to userspace the difference
between aborts via a control message.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-11 15:34:40 -04:00

881 lines
21 KiB
C

/* Maintain an RxRPC server socket to do AFS communications through
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/slab.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include <rxrpc/packet.h>
#include "internal.h"
#include "afs_cm.h"
static 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 int afs_wait_for_call_to_complete(struct afs_call *);
static void afs_wake_up_async_call(struct afs_call *);
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);
/* synchronous call management */
const struct afs_wait_mode afs_sync_call = {
.rx_wakeup = 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,
.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,
};
/* asynchronous incoming call initial processing */
static const struct afs_call_type afs_RXCMxxxx = {
.name = "CB.xxxx",
.deliver = afs_deliver_cm_op_id,
.abort_to_error = afs_abort_to_error,
};
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();
return 0;
}
/*
* open an RxRPC socket and bind it to be a server for callback notifications
* - the socket is left in blocking mode and non-blocking ops use MSG_DONTWAIT
*/
int afs_open_socket(void)
{
struct sockaddr_rxrpc srx;
struct socket *socket;
int ret;
_enter("");
skb_queue_head_init(&afs_incoming_calls);
afs_async_calls = create_singlethread_workqueue("kafsd");
if (!afs_async_calls) {
_leave(" = -ENOMEM [wq]");
return -ENOMEM;
}
ret = sock_create_kern(&init_net, AF_RXRPC, SOCK_DGRAM, PF_INET, &socket);
if (ret < 0) {
destroy_workqueue(afs_async_calls);
_leave(" = %d [socket]", ret);
return ret;
}
socket->sk->sk_allocation = GFP_NOFS;
/* bind the callback manager's address to make this a server socket */
srx.srx_family = AF_RXRPC;
srx.srx_service = CM_SERVICE;
srx.transport_type = SOCK_DGRAM;
srx.transport_len = sizeof(srx.transport.sin);
srx.transport.sin.sin_family = AF_INET;
srx.transport.sin.sin_port = htons(AFS_CM_PORT);
memset(&srx.transport.sin.sin_addr, 0,
sizeof(srx.transport.sin.sin_addr));
ret = kernel_bind(socket, (struct sockaddr *) &srx, sizeof(srx));
if (ret < 0) {
sock_release(socket);
destroy_workqueue(afs_async_calls);
_leave(" = %d [bind]", ret);
return ret;
}
rxrpc_kernel_intercept_rx_messages(socket, afs_rx_interceptor);
afs_socket = socket;
_leave(" = 0");
return 0;
}
/*
* close the RxRPC socket AFS was using
*/
void afs_close_socket(void)
{
_enter("");
wait_on_atomic_t(&afs_outstanding_calls, afs_wait_atomic_t,
TASK_UNINTERRUPTIBLE);
_debug("no outstanding 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 delivered and that the buffer
* should be freed
*/
static void afs_data_delivered(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));
if (atomic_dec_return(&afs_outstanding_skbs) == -1)
BUG();
rxrpc_kernel_data_delivered(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)
{
_debug("DONE %p{%s} [%d]",
call, call->type->name, atomic_read(&afs_outstanding_calls));
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);
kfree(call);
if (atomic_dec_and_test(&afs_outstanding_calls))
wake_up_atomic_t(&afs_outstanding_calls);
}
/*
* End a call but do not free it
*/
static void afs_end_call_nofree(struct afs_call *call)
{
if (call->rxcall) {
rxrpc_kernel_end_call(call->rxcall);
call->rxcall = NULL;
}
if (call->type->destructor)
call->type->destructor(call);
}
/*
* End a call and free it
*/
static void afs_end_call(struct afs_call *call)
{
afs_end_call_nofree(call);
afs_free_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)
{
struct afs_call *call;
call = kzalloc(sizeof(*call), GFP_NOFS);
if (!call)
goto nomem_call;
_debug("CALL %p{%s} [%d]",
call, type->name, atomic_read(&afs_outstanding_calls));
atomic_inc(&afs_outstanding_calls);
call->type = type;
call->request_size = request_size;
call->reply_max = reply_size;
if (request_size) {
call->request = kmalloc(request_size, GFP_NOFS);
if (!call->request)
goto nomem_free;
}
if (reply_size) {
call->buffer = kmalloc(reply_size, GFP_NOFS);
if (!call->buffer)
goto nomem_free;
}
init_waitqueue_head(&call->waitq);
skb_queue_head_init(&call->rx_queue);
return call;
nomem_free:
afs_free_call(call);
nomem_call:
return NULL;
}
/*
* clean up a call with flat buffer
*/
void afs_flat_call_destructor(struct afs_call *call)
{
_enter("");
kfree(call->request);
call->request = NULL;
kfree(call->buffer);
call->buffer = NULL;
}
/*
* attach the data from a bunch of pages on an inode to a call
*/
static int afs_send_pages(struct afs_call *call, struct msghdr *msg,
struct kvec *iov)
{
struct page *pages[8];
unsigned count, n, loop, offset, to;
pgoff_t first = call->first, last = call->last;
int ret;
_enter("");
offset = call->first_offset;
call->first_offset = 0;
do {
_debug("attach %lx-%lx", first, last);
count = last - first + 1;
if (count > ARRAY_SIZE(pages))
count = ARRAY_SIZE(pages);
n = find_get_pages_contig(call->mapping, first, count, pages);
ASSERTCMP(n, ==, count);
loop = 0;
do {
msg->msg_flags = 0;
to = PAGE_SIZE;
if (first + loop >= last)
to = call->last_to;
else
msg->msg_flags = MSG_MORE;
iov->iov_base = kmap(pages[loop]) + offset;
iov->iov_len = to - offset;
offset = 0;
_debug("- range %u-%u%s",
offset, to, msg->msg_flags ? " [more]" : "");
iov_iter_kvec(&msg->msg_iter, WRITE | ITER_KVEC,
iov, 1, to - offset);
/* have to change the state *before* sending the last
* packet as RxRPC might give us the reply before it
* returns from sending the request */
if (first + loop >= last)
call->state = AFS_CALL_AWAIT_REPLY;
ret = rxrpc_kernel_send_data(call->rxcall, msg,
to - offset);
kunmap(pages[loop]);
if (ret < 0)
break;
} while (++loop < count);
first += count;
for (loop = 0; loop < count; loop++)
put_page(pages[loop]);
if (ret < 0)
break;
} while (first <= last);
_leave(" = %d", ret);
return ret;
}
/*
* initiate a call
*/
int afs_make_call(struct in_addr *addr, struct afs_call *call, gfp_t gfp,
const struct afs_wait_mode *wait_mode)
{
struct sockaddr_rxrpc srx;
struct rxrpc_call *rxcall;
struct msghdr msg;
struct kvec iov[1];
int ret;
struct sk_buff *skb;
_enter("%x,{%d},", addr->s_addr, ntohs(call->port));
ASSERT(call->type != NULL);
ASSERT(call->type->name != NULL);
_debug("____MAKE %p{%s,%x} [%d]____",
call, call->type->name, key_serial(call->key),
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);
memset(&srx, 0, sizeof(srx));
srx.srx_family = AF_RXRPC;
srx.srx_service = call->service_id;
srx.transport_type = SOCK_DGRAM;
srx.transport_len = sizeof(srx.transport.sin);
srx.transport.sin.sin_family = AF_INET;
srx.transport.sin.sin_port = call->port;
memcpy(&srx.transport.sin.sin_addr, addr, 4);
/* create a call */
rxcall = rxrpc_kernel_begin_call(afs_socket, &srx, call->key,
(unsigned long) call, gfp);
call->key = NULL;
if (IS_ERR(rxcall)) {
ret = PTR_ERR(rxcall);
goto error_kill_call;
}
call->rxcall = rxcall;
/* send the request */
iov[0].iov_base = call->request;
iov[0].iov_len = call->request_size;
msg.msg_name = NULL;
msg.msg_namelen = 0;
iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC, iov, 1,
call->request_size);
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = (call->send_pages ? MSG_MORE : 0);
/* have to change the state *before* sending the last packet as RxRPC
* might give us the reply before it returns from sending the
* request */
if (!call->send_pages)
call->state = AFS_CALL_AWAIT_REPLY;
ret = rxrpc_kernel_send_data(rxcall, &msg, call->request_size);
if (ret < 0)
goto error_do_abort;
if (call->send_pages) {
ret = afs_send_pages(call, &msg, iov);
if (ret < 0)
goto error_do_abort;
}
/* at this point, an async call may no longer exist as it may have
* already completed */
return wait_mode->wait(call);
error_do_abort:
rxrpc_kernel_abort_call(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);
return ret;
}
/*
* 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 0:
if (last &&
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:
abort_code = RXGEN_CC_UNMARSHAL;
if (call->state != AFS_CALL_AWAIT_REPLY)
abort_code = RXGEN_SS_UNMARSHAL;
do_abort:
rxrpc_kernel_abort_call(call->rxcall,
abort_code);
call->error = ret;
call->state = AFS_CALL_ERROR;
break;
}
afs_data_delivered(skb);
skb = NULL;
continue;
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;
}
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);
}
_leave("");
}
/*
* wait synchronously for a call to complete
*/
static int afs_wait_for_call_to_complete(struct afs_call *call)
{
struct sk_buff *skb;
int ret;
DECLARE_WAITQUEUE(myself, current);
_enter("");
add_wait_queue(&call->waitq, &myself);
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
/* deliver any messages that are in the queue */
if (!skb_queue_empty(&call->rx_queue)) {
__set_current_state(TASK_RUNNING);
afs_deliver_to_call(call);
continue;
}
ret = call->error;
if (call->state >= AFS_CALL_COMPLETE)
break;
ret = -EINTR;
if (signal_pending(current))
break;
schedule();
}
remove_wait_queue(&call->waitq, &myself);
__set_current_state(TASK_RUNNING);
/* kill the call */
if (call->state < AFS_CALL_COMPLETE) {
_debug("call incomplete");
rxrpc_kernel_abort_call(call->rxcall, RX_CALL_DEAD);
while ((skb = skb_dequeue(&call->rx_queue)))
afs_free_skb(skb);
}
_debug("call complete");
afs_end_call(call);
_leave(" = %d", ret);
return ret;
}
/*
* wake up a waiting call
*/
static void afs_wake_up_call_waiter(struct afs_call *call)
{
wake_up(&call->waitq);
}
/*
* wake up an asynchronous call
*/
static void afs_wake_up_async_call(struct afs_call *call)
{
_enter("");
queue_work(afs_async_calls, &call->async_work);
}
/*
* put a call into asynchronous mode
* - mustn't touch the call descriptor as the call my have completed by the
* time we get here
*/
static int afs_dont_wait_for_call_to_complete(struct afs_call *call)
{
_enter("");
return -EINPROGRESS;
}
/*
* delete an asynchronous call
*/
static void afs_delete_async_call(struct afs_call *call)
{
_enter("");
afs_free_call(call);
_leave("");
}
/*
* 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)
{
_enter("");
if (!skb_queue_empty(&call->rx_queue))
afs_deliver_to_call(call);
if (call->state >= AFS_CALL_COMPLETE && call->wait_mode) {
if (call->wait_mode->async_complete)
call->wait_mode->async_complete(call->reply,
call->error);
call->reply = NULL;
/* kill the call */
afs_end_call_nofree(call);
/* we can't just delete the call because the work item may be
* queued */
call->async_workfn = afs_delete_async_call;
queue_work(afs_async_calls, &call->async_work);
}
_leave("");
}
/*
* empty a socket buffer into a flat reply buffer
*/
void afs_transfer_reply(struct afs_call *call, struct sk_buff *skb)
{
size_t len = skb->len;
if (skb_copy_bits(skb, 0, call->buffer + call->reply_size, len) < 0)
BUG();
call->reply_size += len;
}
/*
* 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);
if (!call) {
call = kzalloc(sizeof(struct afs_call), GFP_KERNEL);
if (!call) {
rxrpc_kernel_reject_call(afs_socket);
return;
}
call->async_workfn = afs_process_async_call;
INIT_WORK(&call->async_work, afs_async_workfn);
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]",
call, call->type->name,
atomic_read(&afs_outstanding_calls));
atomic_inc(&afs_outstanding_calls);
}
rxcall = rxrpc_kernel_accept_call(afs_socket,
(unsigned long) call);
if (!IS_ERR(rxcall)) {
call->rxcall = rxcall;
call = NULL;
}
}
if (call)
afs_free_call(call);
}
/*
* grab the operation ID from an incoming cache manager call
*/
static int afs_deliver_cm_op_id(struct afs_call *call, struct sk_buff *skb,
bool last)
{
size_t len = skb->len;
void *oibuf = (void *) &call->operation_ID;
_enter("{%u},{%zu},%d", call->offset, len, last);
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) {
if (last) {
_leave(" = -EBADMSG [op ID short]");
return -EBADMSG;
}
_leave(" = 0 [incomplete]");
return 0;
}
call->state = AFS_CALL_AWAIT_REQUEST;
/* ask the cache manager to route the call (it'll change the call type
* if successful) */
if (!afs_cm_incoming_call(call))
return -ENOTSUPP;
/* pass responsibility for the remainer of this message off to the
* cache manager op */
return call->type->deliver(call, skb, last);
}
/*
* send an empty reply
*/
void afs_send_empty_reply(struct afs_call *call)
{
struct msghdr msg;
_enter("");
msg.msg_name = NULL;
msg.msg_namelen = 0;
iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC, NULL, 0, 0);
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = 0;
call->state = AFS_CALL_AWAIT_ACK;
switch (rxrpc_kernel_send_data(call->rxcall, &msg, 0)) {
case 0:
_leave(" [replied]");
return;
case -ENOMEM:
_debug("oom");
rxrpc_kernel_abort_call(call->rxcall, RX_USER_ABORT);
default:
afs_end_call(call);
_leave(" [error]");
return;
}
}
/*
* send a simple reply
*/
void afs_send_simple_reply(struct afs_call *call, const void *buf, size_t len)
{
struct msghdr msg;
struct kvec iov[1];
int n;
_enter("");
iov[0].iov_base = (void *) buf;
iov[0].iov_len = len;
msg.msg_name = NULL;
msg.msg_namelen = 0;
iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC, iov, 1, len);
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = 0;
call->state = AFS_CALL_AWAIT_ACK;
n = rxrpc_kernel_send_data(call->rxcall, &msg, len);
if (n >= 0) {
/* Success */
_leave(" [replied]");
return;
}
if (n == -ENOMEM) {
_debug("oom");
rxrpc_kernel_abort_call(call->rxcall, RX_USER_ABORT);
}
afs_end_call(call);
_leave(" [error]");
}
/*
* 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)
{
size_t len = skb->len;
_enter("{%u},{%zu},%d,,%zu", call->offset, len, last, 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;
if (call->offset < count) {
if (last) {
_leave(" = -EBADMSG [%d < %zu]", call->offset, count);
return -EBADMSG;
}
_leave(" = -EAGAIN");
return -EAGAIN;
}
return 0;
}