[mirror_ubuntu-artful-kernel.git] / net / core / datagram.c

/*
 *	SUCS NET3:
 *
 *	Generic datagram handling routines. These are generic for all
 *	protocols. Possibly a generic IP version on top of these would
 *	make sense. Not tonight however 8-).
 *	This is used because UDP, RAW, PACKET, DDP, IPX, AX.25 and
 *	NetROM layer all have identical poll code and mostly
 *	identical recvmsg() code. So we share it here. The poll was
 *	shared before but buried in udp.c so I moved it.
 *
 *	Authors:	Alan Cox <alan@redhat.com>. (datagram_poll() from old
 *						     udp.c code)
 *
 *	Fixes:
 *		Alan Cox	:	NULL return from skb_peek_copy()
 *					understood
 *		Alan Cox	:	Rewrote skb_read_datagram to avoid the
 *					skb_peek_copy stuff.
 *		Alan Cox	:	Added support for SOCK_SEQPACKET.
 *					IPX can no longer use the SO_TYPE hack
 *					but AX.25 now works right, and SPX is
 *					feasible.
 *		Alan Cox	:	Fixed write poll of non IP protocol
 *					crash.
 *		Florian  La Roche:	Changed for my new skbuff handling.
 *		Darryl Miles	:	Fixed non-blocking SOCK_SEQPACKET.
 *		Linus Torvalds	:	BSD semantic fixes.
 *		Alan Cox	:	Datagram iovec handling
 *		Darryl Miles	:	Fixed non-blocking SOCK_STREAM.
 *		Alan Cox	:	POSIXisms
 *		Pete Wyckoff    :       Unconnected accept() fix.
 *
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/inet.h>
#include <linux/tcp.h>
#include <linux/netdevice.h>
#include <linux/rtnetlink.h>
#include <linux/poll.h>
#include <linux/highmem.h>

#include <net/protocol.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/checksum.h>


/*
 *	Is a socket 'connection oriented' ?
 */
static inline int connection_based(struct sock *sk)
{
	return sk->sk_type == SOCK_SEQPACKET || sk->sk_type == SOCK_STREAM;
}

/*
 * Wait for a packet..
 */
static int wait_for_packet(struct sock *sk, int *err, long *timeo_p)
{
	int error;
	DEFINE_WAIT(wait);

	prepare_to_wait_exclusive(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);

	/* Socket errors? */
	error = sock_error(sk);
	if (error)
		goto out_err;

	if (!skb_queue_empty(&sk->sk_receive_queue))
		goto out;

	/* Socket shut down? */
	if (sk->sk_shutdown & RCV_SHUTDOWN)
		goto out_noerr;

	/* Sequenced packets can come disconnected.
	 * If so we report the problem
	 */
	error = -ENOTCONN;
	if (connection_based(sk) &&
	    !(sk->sk_state == TCP_ESTABLISHED || sk->sk_state == TCP_LISTEN))
		goto out_err;

	/* handle signals */
	if (signal_pending(current))
		goto interrupted;

	error = 0;
	*timeo_p = schedule_timeout(*timeo_p);
out:
	finish_wait(sk->sk_sleep, &wait);
	return error;
interrupted:
	error = sock_intr_errno(*timeo_p);
out_err:
	*err = error;
	goto out;
out_noerr:
	*err = 0;
	error = 1;
	goto out;
}

/**
 *	skb_recv_datagram - Receive a datagram skbuff
 *	@sk: socket
 *	@flags: MSG_ flags
 *	@noblock: blocking operation?
 *	@err: error code returned
 *
 *	Get a datagram skbuff, understands the peeking, nonblocking wakeups
 *	and possible races. This replaces identical code in packet, raw and
 *	udp, as well as the IPX AX.25 and Appletalk. It also finally fixes
 *	the long standing peek and read race for datagram sockets. If you
 *	alter this routine remember it must be re-entrant.
 *
 *	This function will lock the socket if a skb is returned, so the caller
 *	needs to unlock the socket in that case (usually by calling
 *	skb_free_datagram)
 *
 *	* It does not lock socket since today. This function is
 *	* free of race conditions. This measure should/can improve
 *	* significantly datagram socket latencies at high loads,
 *	* when data copying to user space takes lots of time.
 *	* (BTW I've just killed the last cli() in IP/IPv6/core/netlink/packet
 *	*  8) Great win.)
 *	*			                    --ANK (980729)
 *
 *	The order of the tests when we find no data waiting are specified
 *	quite explicitly by POSIX 1003.1g, don't change them without having
 *	the standard around please.
 */
struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
				  int noblock, int *err)
{
	struct sk_buff *skb;
	long timeo;
	/*
	 * Caller is allowed not to check sk->sk_err before skb_recv_datagram()
	 */
	int error = sock_error(sk);

	if (error)
		goto no_packet;

	timeo = sock_rcvtimeo(sk, noblock);

	do {
		/* Again only user level code calls this function, so nothing
		 * interrupt level will suddenly eat the receive_queue.
		 *
		 * Look at current nfs client by the way...
		 * However, this function was corrent in any case. 8)
		 */
		if (flags & MSG_PEEK) {
			unsigned long cpu_flags;

			spin_lock_irqsave(&sk->sk_receive_queue.lock,
					  cpu_flags);
			skb = skb_peek(&sk->sk_receive_queue);
			if (skb)
				atomic_inc(&skb->users);
			spin_unlock_irqrestore(&sk->sk_receive_queue.lock,
					       cpu_flags);
		} else
			skb = skb_dequeue(&sk->sk_receive_queue);

		if (skb)
			return skb;

		/* User doesn't want to wait */
		error = -EAGAIN;
		if (!timeo)
			goto no_packet;

	} while (!wait_for_packet(sk, err, &timeo));

	return NULL;

no_packet:
	*err = error;
	return NULL;
}

void skb_free_datagram(struct sock *sk, struct sk_buff *skb)
{
	kfree_skb(skb);
}

/**
 *	skb_copy_datagram_iovec - Copy a datagram to an iovec.
 *	@skb: buffer to copy
 *	@offset: offset in the buffer to start copying from
 *	@to: io vector to copy to
 *	@len: amount of data to copy from buffer to iovec
 *
 *	Note: the iovec is modified during the copy.
 */
int skb_copy_datagram_iovec(const struct sk_buff *skb, int offset,
			    struct iovec *to, int len)
{
	int start = skb_headlen(skb);
	int i, copy = start - offset;

	/* Copy header. */
	if (copy > 0) {
		if (copy > len)
			copy = len;
		if (memcpy_toiovec(to, skb->data + offset, copy))
			goto fault;
		if ((len -= copy) == 0)
			return 0;
		offset += copy;
	}

	/* Copy paged appendix. Hmm... why does this look so complicated? */
	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
		int end;

		BUG_TRAP(start <= offset + len);

		end = start + skb_shinfo(skb)->frags[i].size;
		if ((copy = end - offset) > 0) {
			int err;
			u8  *vaddr;
			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
			struct page *page = frag->page;

			if (copy > len)
				copy = len;
			vaddr = kmap(page);
			err = memcpy_toiovec(to, vaddr + frag->page_offset +
					     offset - start, copy);
			kunmap(page);
			if (err)
				goto fault;
			if (!(len -= copy))
				return 0;
			offset += copy;
		}
		start = end;
	}

	if (skb_shinfo(skb)->frag_list) {
		struct sk_buff *list = skb_shinfo(skb)->frag_list;

		for (; list; list = list->next) {
			int end;

			BUG_TRAP(start <= offset + len);

			end = start + list->len;
			if ((copy = end - offset) > 0) {
				if (copy > len)
					copy = len;
				if (skb_copy_datagram_iovec(list,
							    offset - start,
							    to, copy))
					goto fault;
				if ((len -= copy) == 0)
					return 0;
				offset += copy;
			}
			start = end;
		}
	}
	if (!len)
		return 0;

fault:
	return -EFAULT;
}

static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
				      u8 __user *to, int len,
				      unsigned int *csump)
{
	int start = skb_headlen(skb);
	int pos = 0;
	int i, copy = start - offset;

	/* Copy header. */
	if (copy > 0) {
		int err = 0;
		if (copy > len)
			copy = len;
		*csump = csum_and_copy_to_user(skb->data + offset, to, copy,
					       *csump, &err);
		if (err)
			goto fault;
		if ((len -= copy) == 0)
			return 0;
		offset += copy;
		to += copy;
		pos = copy;
	}

	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
		int end;

		BUG_TRAP(start <= offset + len);

		end = start + skb_shinfo(skb)->frags[i].size;
		if ((copy = end - offset) > 0) {
			unsigned int csum2;
			int err = 0;
			u8  *vaddr;
			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
			struct page *page = frag->page;

			if (copy > len)
				copy = len;
			vaddr = kmap(page);
			csum2 = csum_and_copy_to_user(vaddr +
							frag->page_offset +
							offset - start,
						      to, copy, 0, &err);
			kunmap(page);
			if (err)
				goto fault;
			*csump = csum_block_add(*csump, csum2, pos);
			if (!(len -= copy))
				return 0;
			offset += copy;
			to += copy;
			pos += copy;
		}
		start = end;
	}

	if (skb_shinfo(skb)->frag_list) {
		struct sk_buff *list = skb_shinfo(skb)->frag_list;

		for (; list; list=list->next) {
			int end;

			BUG_TRAP(start <= offset + len);

			end = start + list->len;
			if ((copy = end - offset) > 0) {
				unsigned int csum2 = 0;
				if (copy > len)
					copy = len;
				if (skb_copy_and_csum_datagram(list,
							       offset - start,
							       to, copy,
							       &csum2))
					goto fault;
				*csump = csum_block_add(*csump, csum2, pos);
				if ((len -= copy) == 0)
					return 0;
				offset += copy;
				to += copy;
				pos += copy;
			}
			start = end;
		}
	}
	if (!len)
		return 0;

fault:
	return -EFAULT;
}

/**
 *	skb_copy_and_csum_datagram_iovec - Copy and checkum skb to user iovec.
 *	@skb: skbuff
 *	@hlen: hardware length
 *	@iov: io vector
 * 
 *	Caller _must_ check that skb will fit to this iovec.
 *
 *	Returns: 0       - success.
 *		 -EINVAL - checksum failure.
 *		 -EFAULT - fault during copy. Beware, in this case iovec
 *			   can be modified!
 */
int skb_copy_and_csum_datagram_iovec(const struct sk_buff *skb,
				     int hlen, struct iovec *iov)
{
	unsigned int csum;
	int chunk = skb->len - hlen;

	/* Skip filled elements.
	 * Pretty silly, look at memcpy_toiovec, though 8)
	 */
	while (!iov->iov_len)
		iov++;

	if (iov->iov_len < chunk) {
		if ((unsigned short)csum_fold(skb_checksum(skb, 0, chunk + hlen,
							   skb->csum)))
			goto csum_error;
		if (skb_copy_datagram_iovec(skb, hlen, iov, chunk))
			goto fault;
	} else {
		csum = csum_partial(skb->data, hlen, skb->csum);
		if (skb_copy_and_csum_datagram(skb, hlen, iov->iov_base,
					       chunk, &csum))
			goto fault;
		if ((unsigned short)csum_fold(csum))
			goto csum_error;
		iov->iov_len -= chunk;
		iov->iov_base += chunk;
	}
	return 0;
csum_error:
	return -EINVAL;
fault:
	return -EFAULT;
}

/**
 * 	datagram_poll - generic datagram poll
 *	@file: file struct
 *	@sock: socket
 *	@wait: poll table
 *
 *	Datagram poll: Again totally generic. This also handles
 *	sequenced packet sockets providing the socket receive queue
 *	is only ever holding data ready to receive.
 *
 *	Note: when you _don't_ use this routine for this protocol,
 *	and you use a different write policy from sock_writeable()
 *	then please supply your own write_space callback.
 */
unsigned int datagram_poll(struct file *file, struct socket *sock,
			   poll_table *wait)
{
	struct sock *sk = sock->sk;
	unsigned int mask;

	poll_wait(file, sk->sk_sleep, wait);
	mask = 0;

	/* exceptional events? */
	if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
		mask |= POLLERR;
	if (sk->sk_shutdown == SHUTDOWN_MASK)
		mask |= POLLHUP;

	/* readable? */
	if (!skb_queue_empty(&sk->sk_receive_queue) ||
	    (sk->sk_shutdown & RCV_SHUTDOWN))
		mask |= POLLIN | POLLRDNORM;

	/* Connection-based need to check for termination and startup */
	if (connection_based(sk)) {
		if (sk->sk_state == TCP_CLOSE)
			mask |= POLLHUP;
		/* connection hasn't started yet? */
		if (sk->sk_state == TCP_SYN_SENT)
			return mask;
	}

	/* writable? */
	if (sock_writeable(sk))
		mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
	else
		set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);

	return mask;
}

EXPORT_SYMBOL(datagram_poll);
EXPORT_SYMBOL(skb_copy_and_csum_datagram_iovec);
EXPORT_SYMBOL(skb_copy_datagram_iovec);
EXPORT_SYMBOL(skb_free_datagram);
EXPORT_SYMBOL(skb_recv_datagram);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* SUCS NET3:
	3	*
	4	* Generic datagram handling routines. These are generic for all
	5	* protocols. Possibly a generic IP version on top of these would
	6	* make sense. Not tonight however 8-).
	7	* This is used because UDP, RAW, PACKET, DDP, IPX, AX.25 and
	8	* NetROM layer all have identical poll code and mostly
	9	* identical recvmsg() code. So we share it here. The poll was
	10	* shared before but buried in udp.c so I moved it.
	11	*
	12	* Authors: Alan Cox <alan@redhat.com>. (datagram_poll() from old
	13	* udp.c code)
	14	*
	15	* Fixes:
	16	* Alan Cox : NULL return from skb_peek_copy()
	17	* understood
	18	* Alan Cox : Rewrote skb_read_datagram to avoid the
	19	* skb_peek_copy stuff.
	20	* Alan Cox : Added support for SOCK_SEQPACKET.
	21	* IPX can no longer use the SO_TYPE hack
	22	* but AX.25 now works right, and SPX is
	23	* feasible.
	24	* Alan Cox : Fixed write poll of non IP protocol
	25	* crash.
	26	* Florian La Roche: Changed for my new skbuff handling.
	27	* Darryl Miles : Fixed non-blocking SOCK_SEQPACKET.
	28	* Linus Torvalds : BSD semantic fixes.
	29	* Alan Cox : Datagram iovec handling
	30	* Darryl Miles : Fixed non-blocking SOCK_STREAM.
	31	* Alan Cox : POSIXisms
	32	* Pete Wyckoff : Unconnected accept() fix.
	33	*
	34	*/
	35
	36	#include <linux/module.h>
	37	#include <linux/types.h>
	38	#include <linux/kernel.h>
	39	#include <asm/uaccess.h>
	40	#include <asm/system.h>
	41	#include <linux/mm.h>
	42	#include <linux/interrupt.h>
	43	#include <linux/errno.h>
	44	#include <linux/sched.h>
	45	#include <linux/inet.h>
	46	#include <linux/tcp.h>
	47	#include <linux/netdevice.h>
	48	#include <linux/rtnetlink.h>
	49	#include <linux/poll.h>
	50	#include <linux/highmem.h>
	51
	52	#include <net/protocol.h>
	53	#include <linux/skbuff.h>
	54	#include <net/sock.h>
	55	#include <net/checksum.h>
	56
	57
	58	/*
	59	* Is a socket 'connection oriented' ?
	60	*/
	61	static inline int connection_based(struct sock *sk)
	62	{
	63	return sk->sk_type == SOCK_SEQPACKET \|\| sk->sk_type == SOCK_STREAM;
	64	}
65
66	/*
67	* Wait for a packet..
68	*/
69	static int wait_for_packet(struct sock sk, int err, long *timeo_p)
70	{
71	int error;
72	DEFINE_WAIT(wait);
73
74	prepare_to_wait_exclusive(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
75
76	/* Socket errors? */
77	error = sock_error(sk);
78	if (error)
79	goto out_err;
80
81	if (!skb_queue_empty(&sk->sk_receive_queue))
82	goto out;
83
84	/* Socket shut down? */
85	if (sk->sk_shutdown & RCV_SHUTDOWN)
86	goto out_noerr;
87
88	/* Sequenced packets can come disconnected.
89	* If so we report the problem
90	*/
91	error = -ENOTCONN;
92	if (connection_based(sk) &&
93	!(sk->sk_state == TCP_ESTABLISHED \|\| sk->sk_state == TCP_LISTEN))
94	goto out_err;
95
96	/* handle signals */
97	if (signal_pending(current))
98	goto interrupted;
99
100	error = 0;
101	timeo_p = schedule_timeout(timeo_p);
102	out:
103	finish_wait(sk->sk_sleep, &wait);
104	return error;
105	interrupted:
106	error = sock_intr_errno(*timeo_p);
107	out_err:
108	*err = error;
109	goto out;
110	out_noerr:
111	*err = 0;
112	error = 1;
113	goto out;
114	}
115
116	/**
117	* skb_recv_datagram - Receive a datagram skbuff
4dc3b16b PP	118	* @sk: socket
	119	* @flags: MSG_ flags
	120	* @noblock: blocking operation?
	121	* @err: error code returned
1da177e4 LT	122	*
	123	* Get a datagram skbuff, understands the peeking, nonblocking wakeups
	124	* and possible races. This replaces identical code in packet, raw and
	125	* udp, as well as the IPX AX.25 and Appletalk. It also finally fixes
	126	* the long standing peek and read race for datagram sockets. If you
	127	* alter this routine remember it must be re-entrant.
	128	*
	129	* This function will lock the socket if a skb is returned, so the caller
	130	* needs to unlock the socket in that case (usually by calling
	131	* skb_free_datagram)
	132	*
	133	* * It does not lock socket since today. This function is
	134	* * free of race conditions. This measure should/can improve
	135	* * significantly datagram socket latencies at high loads,
	136	* * when data copying to user space takes lots of time.
	137	* * (BTW I've just killed the last cli() in IP/IPv6/core/netlink/packet
	138	* * 8) Great win.)
	139	* * --ANK (980729)
	140	*
	141	* The order of the tests when we find no data waiting are specified
	142	* quite explicitly by POSIX 1003.1g, don't change them without having
	143	* the standard around please.
	144	*/
	145	struct sk_buff skb_recv_datagram(struct sock sk, unsigned flags,
	146	int noblock, int *err)
	147	{
	148	struct sk_buff *skb;
	149	long timeo;
	150	/*
	151	* Caller is allowed not to check sk->sk_err before skb_recv_datagram()
	152	*/
	153	int error = sock_error(sk);
	154
	155	if (error)
	156	goto no_packet;
	157
	158	timeo = sock_rcvtimeo(sk, noblock);
	159
	160	do {
	161	/* Again only user level code calls this function, so nothing
	162	* interrupt level will suddenly eat the receive_queue.
	163	*
	164	* Look at current nfs client by the way...
	165	* However, this function was corrent in any case. 8)
	166	*/
	167	if (flags & MSG_PEEK) {
	168	unsigned long cpu_flags;
	169
	170	spin_lock_irqsave(&sk->sk_receive_queue.lock,
	171	cpu_flags);
	172	skb = skb_peek(&sk->sk_receive_queue);
	173	if (skb)
	174	atomic_inc(&skb->users);
	175	spin_unlock_irqrestore(&sk->sk_receive_queue.lock,
	176	cpu_flags);
	177	} else
	178	skb = skb_dequeue(&sk->sk_receive_queue);
	179
	180	if (skb)
	181	return skb;
	182
	183	/* User doesn't want to wait */
	184	error = -EAGAIN;
	185	if (!timeo)
186	goto no_packet;
187
188	} while (!wait_for_packet(sk, err, &timeo));
189
190	return NULL;
191
192	no_packet:
193	*err = error;
194	return NULL;
195	}
196
197	void skb_free_datagram(struct sock sk, struct sk_buff skb)
198	{
199	kfree_skb(skb);
200	}
201
202	/**
203	* skb_copy_datagram_iovec - Copy a datagram to an iovec.
4dc3b16b PP	204	* @skb: buffer to copy
4dc3b16b PP	205	* @offset: offset in the buffer to start copying from
67be2dd1	206	* @to: io vector to copy to
4dc3b16b	207	* @len: amount of data to copy from buffer to iovec
1da177e4 LT	208	*
	209	* Note: the iovec is modified during the copy.
	210	*/
	211	int skb_copy_datagram_iovec(const struct sk_buff *skb, int offset,
	212	struct iovec *to, int len)
	213	{
	214	int start = skb_headlen(skb);
	215	int i, copy = start - offset;
	216
	217	/* Copy header. */
	218	if (copy > 0) {
	219	if (copy > len)
	220	copy = len;
	221	if (memcpy_toiovec(to, skb->data + offset, copy))
	222	goto fault;
	223	if ((len -= copy) == 0)
	224	return 0;
	225	offset += copy;
	226	}
	227
	228	/* Copy paged appendix. Hmm... why does this look so complicated? */
	229	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
	230	int end;
	231
	232	BUG_TRAP(start <= offset + len);
	233
	234	end = start + skb_shinfo(skb)->frags[i].size;
	235	if ((copy = end - offset) > 0) {
	236	int err;
	237	u8 *vaddr;
	238	skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
	239	struct page *page = frag->page;
	240
	241	if (copy > len)
	242	copy = len;
	243	vaddr = kmap(page);
	244	err = memcpy_toiovec(to, vaddr + frag->page_offset +
	245	offset - start, copy);
	246	kunmap(page);
	247	if (err)
	248	goto fault;
	249	if (!(len -= copy))
	250	return 0;
	251	offset += copy;
	252	}
	253	start = end;
	254	}
	255
	256	if (skb_shinfo(skb)->frag_list) {
	257	struct sk_buff *list = skb_shinfo(skb)->frag_list;
	258
	259	for (; list; list = list->next) {
	260	int end;
	261
	262	BUG_TRAP(start <= offset + len);
	263
	264	end = start + list->len;
	265	if ((copy = end - offset) > 0) {
	266	if (copy > len)
	267	copy = len;
	268	if (skb_copy_datagram_iovec(list,
	269	offset - start,
	270	to, copy))
	271	goto fault;
272	if ((len -= copy) == 0)
273	return 0;
274	offset += copy;
275	}
276	start = end;
277	}
278	}
279	if (!len)
280	return 0;
281
282	fault:
283	return -EFAULT;
284	}
285
286	static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
287	u8 __user *to, int len,
288	unsigned int *csump)
289	{
290	int start = skb_headlen(skb);
291	int pos = 0;
292	int i, copy = start - offset;
293
294	/* Copy header. */
295	if (copy > 0) {
296	int err = 0;
297	if (copy > len)
298	copy = len;
299	*csump = csum_and_copy_to_user(skb->data + offset, to, copy,
300	*csump, &err);
301	if (err)
302	goto fault;
303	if ((len -= copy) == 0)
304	return 0;
305	offset += copy;
306	to += copy;
307	pos = copy;
308	}
309
310	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
311	int end;
312
313	BUG_TRAP(start <= offset + len);
314
315	end = start + skb_shinfo(skb)->frags[i].size;
316	if ((copy = end - offset) > 0) {
317	unsigned int csum2;
318	int err = 0;
319	u8 *vaddr;
320	skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
321	struct page *page = frag->page;
322
323	if (copy > len)
324	copy = len;
325	vaddr = kmap(page);
326	csum2 = csum_and_copy_to_user(vaddr +
327	frag->page_offset +
328	offset - start,
329	to, copy, 0, &err);
330	kunmap(page);
331	if (err)
332	goto fault;
333	csump = csum_block_add(csump, csum2, pos);
334	if (!(len -= copy))
335	return 0;
336	offset += copy;
337	to += copy;
338	pos += copy;
339	}
340	start = end;
341	}
342
343	if (skb_shinfo(skb)->frag_list) {
344	struct sk_buff *list = skb_shinfo(skb)->frag_list;
345
346	for (; list; list=list->next) {
347	int end;
348
349	BUG_TRAP(start <= offset + len);
350
351	end = start + list->len;
352	if ((copy = end - offset) > 0) {
353	unsigned int csum2 = 0;
354	if (copy > len)
355	copy = len;
356	if (skb_copy_and_csum_datagram(list,
357	offset - start,
358	to, copy,
359	&csum2))
360	goto fault;
361	csump = csum_block_add(csump, csum2, pos);
362	if ((len -= copy) == 0)
363	return 0;
364	offset += copy;
365	to += copy;
366	pos += copy;
367	}
368	start = end;
369	}
370	}
371	if (!len)
372	return 0;
373
374	fault:
375	return -EFAULT;
376	}
377
378	/**
379	* skb_copy_and_csum_datagram_iovec - Copy and checkum skb to user iovec.
4dc3b16b PP	380	* @skb: skbuff
4dc3b16b PP	381	* @hlen: hardware length
67be2dd1	382	* @iov: io vector
1da177e4 LT	383	*
	384	* Caller _must_ check that skb will fit to this iovec.
	385	*
	386	* Returns: 0 - success.
	387	* -EINVAL - checksum failure.
	388	* -EFAULT - fault during copy. Beware, in this case iovec
	389	* can be modified!
	390	*/
	391	int skb_copy_and_csum_datagram_iovec(const struct sk_buff *skb,
	392	int hlen, struct iovec *iov)
	393	{
	394	unsigned int csum;
	395	int chunk = skb->len - hlen;
	396
	397	/* Skip filled elements.
	398	* Pretty silly, look at memcpy_toiovec, though 8)
	399	*/
	400	while (!iov->iov_len)
	401	iov++;
	402
	403	if (iov->iov_len < chunk) {
	404	if ((unsigned short)csum_fold(skb_checksum(skb, 0, chunk + hlen,
	405	skb->csum)))
	406	goto csum_error;
	407	if (skb_copy_datagram_iovec(skb, hlen, iov, chunk))
	408	goto fault;
	409	} else {
	410	csum = csum_partial(skb->data, hlen, skb->csum);
	411	if (skb_copy_and_csum_datagram(skb, hlen, iov->iov_base,
	412	chunk, &csum))
	413	goto fault;
	414	if ((unsigned short)csum_fold(csum))
	415	goto csum_error;
	416	iov->iov_len -= chunk;
	417	iov->iov_base += chunk;
	418	}
	419	return 0;
	420	csum_error:
	421	return -EINVAL;
	422	fault:
	423	return -EFAULT;
	424	}
	425
	426	/**
	427	* datagram_poll - generic datagram poll
4dc3b16b PP	428	* @file: file struct
	429	* @sock: socket
	430	* @wait: poll table
1da177e4 LT	431	*
	432	* Datagram poll: Again totally generic. This also handles
	433	* sequenced packet sockets providing the socket receive queue
	434	* is only ever holding data ready to receive.
	435	*
	436	* Note: when you _don't_ use this routine for this protocol,
	437	* and you use a different write policy from sock_writeable()
	438	* then please supply your own write_space callback.
	439	*/
	440	unsigned int datagram_poll(struct file file, struct socket sock,
	441	poll_table *wait)
	442	{
	443	struct sock *sk = sock->sk;
	444	unsigned int mask;
	445
	446	poll_wait(file, sk->sk_sleep, wait);
	447	mask = 0;
	448
	449	/* exceptional events? */
	450	if (sk->sk_err \|\| !skb_queue_empty(&sk->sk_error_queue))
	451	mask \|= POLLERR;
	452	if (sk->sk_shutdown == SHUTDOWN_MASK)
	453	mask \|= POLLHUP;
	454
	455	/* readable? */
	456	if (!skb_queue_empty(&sk->sk_receive_queue) \|\|
	457	(sk->sk_shutdown & RCV_SHUTDOWN))
	458	mask \|= POLLIN \| POLLRDNORM;
	459
	460	/* Connection-based need to check for termination and startup */
	461	if (connection_based(sk)) {
	462	if (sk->sk_state == TCP_CLOSE)
	463	mask \|= POLLHUP;
	464	/* connection hasn't started yet? */
	465	if (sk->sk_state == TCP_SYN_SENT)
	466	return mask;
	467	}
	468
	469	/* writable? */
	470	if (sock_writeable(sk))
	471	mask \|= POLLOUT \| POLLWRNORM \| POLLWRBAND;
	472	else
	473	set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
	474
	475	return mask;
	476	}
	477
	478	EXPORT_SYMBOL(datagram_poll);
	479	EXPORT_SYMBOL(skb_copy_and_csum_datagram_iovec);
	480	EXPORT_SYMBOL(skb_copy_datagram_iovec);
	481	EXPORT_SYMBOL(skb_free_datagram);
	482	EXPORT_SYMBOL(skb_recv_datagram);