// SPDX-License-Identifier: GPL-2.0
/*
* 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 <[email protected]>. (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 <linux/uaccess.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/rtnetlink.h>
#include <linux/poll.h>
#include <linux/highmem.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/iov_iter.h>
#include <linux/indirect_call_wrapper.h>
#include <net/protocol.h>
#include <linux/skbuff.h>
#include <net/checksum.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <trace/events/skb.h>
#include <net/busy_poll.h>
#include <crypto/hash.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;
}
static int receiver_wake_function(wait_queue_entry_t *wait, unsigned int mode, int sync,
void *key)
{
/*
* Avoid a wakeup if event not interesting for us
*/
if (key && !(key_to_poll(key) & (EPOLLIN | EPOLLERR)))
return 0;
return autoremove_wake_function(wait, mode, sync, key);
}
/*
* Wait for the last received packet to be different from skb
*/
int __skb_wait_for_more_packets(struct sock *sk, struct sk_buff_head *queue,
int *err, long *timeo_p,
const struct sk_buff *skb)
{
int error;
DEFINE_WAIT_FUNC(wait, receiver_wake_function);
prepare_to_wait_exclusive(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
/* Socket errors? */
error = sock_error(sk);
if (error)
goto out_err;
if (READ_ONCE(queue->prev) != skb)
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_sleep(sk), &wait);
return error;
interrupted:
error = sock_intr_errno(*timeo_p);
out_err:
*err = error;
goto out;
out_noerr:
*err = 0;
error = 1;
goto out;
}
EXPORT_SYMBOL(__skb_wait_for_more_packets);
static struct sk_buff *skb_set_peeked(struct sk_buff *skb)
{
struct sk_buff *nskb;
if (skb->peeked)
return skb;
/* We have to unshare an skb before modifying it. */
if (!skb_shared(skb))
goto done;
nskb = skb_clone(skb, GFP_ATOMIC);
if (!nskb)
return ERR_PTR(-ENOMEM);
skb->prev->next = nskb;
skb->next->prev = nskb;
nskb->prev = skb->prev;
nskb->next = skb->next;
consume_skb(skb);
skb = nskb;
done:
skb->peeked = 1;
return skb;
}
struct sk_buff *__skb_try_recv_from_queue(struct sock *sk,
struct sk_buff_head *queue,
unsigned int flags,
int *off, int *err,
struct sk_buff **last)
{
bool peek_at_off = false;
struct sk_buff *skb;
int _off = 0;
if (unlikely(flags & MSG_PEEK && *off >= 0)) {
peek_at_off = true;
_off = *off;
}
*last = queue->prev;
skb_queue_walk(queue, skb) {
if (flags & MSG_PEEK) {
if (peek_at_off && _off >= skb->len &&
(_off || skb->peeked)) {
_off -= skb->len;
continue;
}
if (!skb->len) {
skb = skb_set_peeked(skb);
if (IS_ERR(skb)) {
*err = PTR_ERR(skb);
return NULL;
}
}
refcount_inc(&skb->users);
} else {
__skb_unlink(skb, queue);
}
*off = _off;
return skb;
}
return NULL;
}
/**
* __skb_try_recv_datagram - Receive a datagram skbuff
* @sk: socket
* @queue: socket queue from which to receive
* @flags: MSG\_ flags
* @off: an offset in bytes to peek skb from. Returns an offset
* within an skb where data actually starts
* @err: error code returned
* @last: set to last peeked message to inform the wait function
* what to look for when peeking
*
* 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). Returns NULL with @err set to
* -EAGAIN if no data was available or to some other value if an
* error was detected.
*
* * 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_try_recv_datagram(struct sock *sk,
struct sk_buff_head *queue,
unsigned int flags, int *off, int *err,
struct sk_buff **last)
{
struct sk_buff *skb;
unsigned long cpu_flags;
/*
* Caller is allowed not to check sk->sk_err before skb_recv_datagram()
*/
int error = sock_error(sk);
if (error)
goto no_packet;
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 correct in any case. 8)
*/
spin_lock_irqsave(&queue->lock, cpu_flags);
skb = __skb_try_recv_from_queue(sk, queue, flags, off, &error,
last);
spin_unlock_irqrestore(&queue->lock, cpu_flags);
if (error)
goto no_packet;
if (skb)
return skb;
if (!sk_can_busy_loop(sk))
break;
sk_busy_loop(sk, flags & MSG_DONTWAIT);
} while (READ_ONCE(queue->prev) != *last);
error = -EAGAIN;
no_packet:
*err = error;
return NULL;
}
EXPORT_SYMBOL(__skb_try_recv_datagram);
struct sk_buff *__skb_recv_datagram(struct sock *sk,
struct sk_buff_head *sk_queue,
unsigned int flags, int *off, int *err)
{
struct sk_buff *skb, *last;
long timeo;
timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
do {
skb = __skb_try_recv_datagram(sk, sk_queue, flags, off, err,
&last);
if (skb)
return skb;
if (*err != -EAGAIN)
break;
} while (timeo &&
!__skb_wait_for_more_packets(sk, sk_queue, err,
&timeo, last));
return NULL;
}
EXPORT_SYMBOL(__skb_recv_datagram);
struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned int flags,
int *err)
{
int off = 0;
return __skb_recv_datagram(sk, &sk->sk_receive_queue, flags,
&off, err);
}
EXPORT_SYMBOL(skb_recv_datagram);
void skb_free_datagram(struct sock *sk, struct sk_buff *skb)
{
consume_skb(skb);
}
EXPORT_SYMBOL(skb_free_datagram);
int __sk_queue_drop_skb(struct sock *sk, struct sk_buff_head *sk_queue,
struct sk_buff *skb, unsigned int flags,
void (*destructor)(struct sock *sk,
struct sk_buff *skb))
{
int err = 0;
if (flags & MSG_PEEK) {
err = -ENOENT;
spin_lock_bh(&sk_queue->lock);
if (skb->next) {
__skb_unlink(skb, sk_queue);
refcount_dec(&skb->users);
if (destructor)
destructor(sk, skb);
err = 0;
}
spin_unlock_bh(&sk_queue->lock);
}
atomic_inc(&sk->sk_drops);
return err;
}
EXPORT_SYMBOL(__sk_queue_drop_skb);
/**
* skb_kill_datagram - Free a datagram skbuff forcibly
* @sk: socket
* @skb: datagram skbuff
* @flags: MSG\_ flags
*
* This function frees a datagram skbuff that was received by
* skb_recv_datagram. The flags argument must match the one
* used for skb_recv_datagram.
*
* If the MSG_PEEK flag is set, and the packet is still on the
* receive queue of the socket, it will be taken off the queue
* before it is freed.
*
* This function currently only disables BH when acquiring the
* sk_receive_queue lock. Therefore it must not be used in a
* context where that lock is acquired in an IRQ context.
*
* It returns 0 if the packet was removed by us.
*/
int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags)
{
int err = __sk_queue_drop_skb(sk, &sk->sk_receive_queue, skb, flags,
NULL);
kfree_skb(skb);
return err;
}
EXPORT_SYMBOL(skb_kill_datagram);
INDIRECT_CALLABLE_DECLARE(static size_t simple_copy_to_iter(const void *addr,
size_t bytes,
void *data __always_unused,
struct iov_iter *i));
static int __skb_datagram_iter(const struct sk_buff *skb, int offset,
struct iov_iter *to, int len, bool fault_short,
size_t (*cb)(const void *, size_t, void *,
struct iov_iter *), void *data)
{
int start = skb_headlen(skb);
int i, copy = start - offset, start_off = offset, n;
struct sk_buff *frag_iter;
/* Copy header. */
if (copy > 0) {
if (copy > len)
copy = len;
n = INDIRECT_CALL_1(cb, simple_copy_to_iter,
skb->data + offset, copy, data, to);
offset += n;
if (n != copy)
goto short_copy;
if ((len -= copy) == 0)
return 0;
}
if (!skb_frags_readable(skb))
goto short_copy;
/* Copy paged appendix. Hmm... why does this look so complicated? */
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
int end;
const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
WARN_ON(start > offset + len);
end = start + skb_frag_size(frag);
if ((copy = end - offset) > 0) {
u32 p_off, p_len, copied;
struct page *p;
u8 *vaddr;
if (copy > len)
copy = len;
n = 0;
skb_frag_foreach_page(frag,
skb_frag_off(frag) + offset - start,
copy, p, p_off, p_len, copied) {
vaddr = kmap_local_page(p);
n += INDIRECT_CALL_1(cb, simple_copy_to_iter,
vaddr + p_off, p_len, data, to);
kunmap_local(vaddr);
}
offset += n;
if (n != copy)
goto short_copy;
if (!(len -= copy))
return 0;
}
start = end;
}
skb_walk_frags(skb, frag_iter) {
int end;
WARN_ON(start > offset + len);
end = start + frag_iter->len;
if ((copy = end - offset) > 0) {
if (copy > len)
copy = len;
if (__skb_datagram_iter(frag_iter, offset - start,
to, copy, fault_short, cb, data))
goto fault;
if ((len -= copy) == 0)
return 0;
offset += copy;
}
start = end;
}
if (!len)
return 0;
/* This is not really a user copy fault, but rather someone
* gave us a bogus length on the skb. We should probably
* print a warning here as it may indicate a kernel bug.
*/
fault:
iov_iter_revert(to, offset - start_off);
return -EFAULT;
short_copy:
if (fault_short || iov_iter_count(to))
goto fault;
return 0;
}
static size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
struct iov_iter *i)
{
#ifdef CONFIG_CRYPTO_HASH
struct ahash_request *hash = hashp;
struct scatterlist sg;
size_t copied;
copied = copy_to_iter(addr, bytes, i);
sg_init_one(&sg, addr, copied);
ahash_request_set_crypt(hash, &sg, NULL, copied);
crypto_ahash_update(hash);
return copied;
#else
return 0;
#endif
}
/**
* skb_copy_and_hash_datagram_iter - Copy datagram to an iovec iterator
* and update a hash.
* @skb: buffer to copy
* @offset: offset in the buffer to start copying from
* @to: iovec iterator to copy to
* @len: amount of data to copy from buffer to iovec
* @hash: hash request to update
*/
int skb_copy_and_hash_datagram_iter(const struct sk_buff *skb, int offset,
struct iov_iter *to, int len,
struct ahash_request *hash)
{
return __skb_datagram_iter(skb, offset, to, len, true,
hash_and_copy_to_iter, hash);
}
EXPORT_SYMBOL(skb_copy_and_hash_datagram_iter);
static size_t simple_copy_to_iter(const void *addr, size_t bytes,
void *data __always_unused, struct iov_iter *i)
{
return copy_to_iter(addr, bytes, i);
}
/**
* skb_copy_datagram_iter - Copy a datagram to an iovec iterator.
* @skb: buffer to copy
* @offset: offset in the buffer to start copying from
* @to: iovec iterator to copy to
* @len: amount of data to copy from buffer to iovec
*/
int skb_copy_datagram_iter(const struct sk_buff *skb, int offset,
struct iov_iter *to, int len)
{
trace_skb_copy_datagram_iovec(skb, len);
return __skb_datagram_iter(skb, offset, to, len, false,
simple_copy_to_iter, NULL);
}
EXPORT_SYMBOL(skb_copy_datagram_iter);
/**
* skb_copy_datagram_from_iter - Copy a datagram from an iov_iter.
* @skb: buffer to copy
* @offset: offset in the buffer to start copying to
* @from: the copy source
* @len: amount of data to copy to buffer from iovec
*
* Returns 0 or -EFAULT.
*/
int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
struct iov_iter *from,
int len)
{
int start = skb_headlen(skb);
int i, copy = start - offset;
struct sk_buff *frag_iter;
/* Copy header. */
if (copy > 0) {
if (copy > len)
copy = len;
if (copy_from_iter(skb->data + offset, copy, from) != 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;
const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
WARN_ON(start > offset + len);
end = start + skb_frag_size(frag);
if ((copy = end - offset) > 0) {
size_t copied;
if (copy > len)
copy = len;
copied = copy_page_from_iter(skb_frag_page(frag),
skb_frag_off(frag) + offset - start,
copy, from);
if (copied != copy)
goto fault;
if (!(len -= copy))
return 0;
offset += copy;
}
start = end;
}
skb_walk_frags(skb, frag_iter) {
int end;
WARN_ON(start > offset + len);
end = start + frag_iter->len;
if ((copy = end - offset) > 0) {
if (copy > len)
copy = len;
if (skb_copy_datagram_from_iter(frag_iter,
offset - start,
from, copy))
goto fault;
if ((len -= copy) == 0)
return 0;
offset += copy;
}
start = end;
}
if (!len)
return 0;
fault:
return -EFAULT;
}
EXPORT_SYMBOL(skb_copy_datagram_from_iter);
int zerocopy_fill_skb_from_iter(struct sk_buff *skb,
struct iov_iter *from, size_t length)
{
int frag = skb_shinfo(skb)->nr_frags;
if (!skb_frags_readable(skb))
return -EFAULT;
while (length && iov_iter_count(from)) {
struct page *head, *last_head = NULL;
struct page *pages[MAX_SKB_FRAGS];
int refs, order, n = 0;
size_t start;
ssize_t copied;
if (frag == MAX_SKB_FRAGS)
return -EMSGSIZE;
copied = iov_iter_get_pages2(from, pages, length,
MAX_SKB_FRAGS - frag, &start);
if (copied < 0)
return -EFAULT;
length -= copied;
skb->data_len += copied;
skb->len += copied;
skb->truesize += PAGE_ALIGN(copied + start);
head = compound_head(pages[n]);
order = compound_order(head);
for (refs = 0; copied != 0; start = 0) {
int size = min_t(int, copied, PAGE_SIZE - start);
if (pages[n] - head > (1UL << order) - 1) {
head = compound_head(pages[n]);
order = compound_order(head);
}
start += (pages[n] - head) << PAGE_SHIFT;
copied -= size;
n++;
if (frag) {
skb_frag_t *last = &skb_shinfo(skb)->frags[frag - 1];
if (head == skb_frag_page(last) &&
start == skb_frag_off(last) + skb_frag_size(last)) {
skb_frag_size_add(last, size);
/* We combined this page, we need to release
* a reference. Since compound pages refcount
* is shared among many pages, batch the refcount
* adjustments to limit false sharing.
*/
last_head = head;
refs++;
continue;
}
}
if (refs) {
page_ref_sub(last_head, refs);
refs = 0;
}
skb_fill_page_desc_noacc(skb, frag++, head, start, size);
}
if (refs)
page_ref_sub(last_head, refs);
}
return 0;
}
int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
struct sk_buff *skb, struct iov_iter *from,
size_t length)
{
unsigned long orig_size = skb->truesize;
unsigned long truesize;
int ret;
if (msg && msg->msg_ubuf && msg->sg_from_iter)
ret = msg->sg_from_iter(skb, from, length);
else
ret = zerocopy_fill_skb_from_iter(skb, from, length);
truesize = skb->truesize - orig_size;
if (sk && sk->sk_type == SOCK_STREAM) {
sk_wmem_queued_add(sk, truesize);
if (!skb_zcopy_pure(skb))
sk_mem_charge(sk, truesize);
} else {
refcount_add(truesize, &skb->sk->sk_wmem_alloc);
}
return ret;
}
EXPORT_SYMBOL(__zerocopy_sg_from_iter);
/**
* zerocopy_sg_from_iter - Build a zerocopy datagram from an iov_iter
* @skb: buffer to copy
* @from: the source to copy from
*
* The function will first copy up to headlen, and then pin the userspace
* pages and build frags through them.
*
* Returns 0, -EFAULT or -EMSGSIZE.
*/
int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *from)
{
int copy = min_t(int, skb_headlen(skb), iov_iter_count(from));
/* copy up to skb headlen */
if (skb_copy_datagram_from_iter(skb, 0, from, copy))
return -EFAULT;
return __zerocopy_sg_from_iter(NULL, NULL, skb, from, ~0U);
}
EXPORT_SYMBOL(zerocopy_sg_from_iter);
static __always_inline
size_t copy_to_user_iter_csum(void __user *iter_to, size_t progress,
size_t len, void *from, void *priv2)
{
__wsum next, *csum = priv2;
next = csum_and_copy_to_user(from + progress, iter_to, len);
*csum = csum_block_add(*csum, next, progress);
return next ? 0 : len;
}
static __always_inline
size_t memcpy_to_iter_csum(void *iter_to, size_t progress,
size_t len, void *from, void *priv2)
{
__wsum *csum = priv2;
__wsum next = csum_partial_copy_nocheck(from + progress, iter_to, len);
*csum = csum_block_add(*csum, next, progress);
return 0;
}
struct csum_state {
__wsum csum;
size_t off;
};
static size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate,
struct iov_iter *i)
{
struct csum_state *csstate = _csstate;
__wsum sum;
if (WARN_ON_ONCE(i->data_source))
return 0;
if (unlikely(iov_iter_is_discard(i))) {
// can't use csum_memcpy() for that one - data is not copied
csstate->csum = csum_block_add(csstate->csum,
csum_partial(addr, bytes, 0),
csstate->off);
csstate->off += bytes;
return bytes;
}
sum = csum_shift(csstate->csum, csstate->off);
bytes = iterate_and_advance2(i, bytes, (void *)addr, &sum,
copy_to_user_iter_csum,
memcpy_to_iter_csum);
csstate->csum = csum_shift(sum, csstate->off);
csstate->off += bytes;
return bytes;
}
/**
* skb_copy_and_csum_datagram - Copy datagram to an iovec iterator
* and update a checksum.
* @skb: buffer to copy
* @offset: offset in the buffer to start copying from
* @to: iovec iterator to copy to
* @len: amount of data to copy from buffer to iovec
* @csump: checksum pointer
*/
static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
struct iov_iter *to, int len,
__wsum *csump)
{
struct csum_state csdata = { .csum = *csump };
int ret;
ret = __skb_datagram_iter(skb, offset, to, len, true,
csum_and_copy_to_iter, &csdata);
if (ret)
return ret;
*csump = csdata.csum;
return 0;
}
/**
* skb_copy_and_csum_datagram_msg - Copy and checksum skb to user iovec.
* @skb: skbuff
* @hlen: hardware length
* @msg: destination
*
* Caller _must_ check that skb will fit to this iovec.
*
* Returns: 0 - success.
* -EINVAL - checksum failure.
* -EFAULT - fault during copy.
*/
int skb_copy_and_csum_datagram_msg(struct sk_buff *skb,
int hlen, struct msghdr *msg)
{
__wsum csum;
int chunk = skb->len - hlen;
if (!chunk)
return 0;
if (msg_data_left(msg) < chunk) {
if (__skb_checksum_complete(skb))
return -EINVAL;
if (skb_copy_datagram_msg(skb, hlen, msg, chunk))
goto fault;
} else {
csum = csum_partial(skb->data, hlen, skb->csum);
if (skb_copy_and_csum_datagram(skb, hlen, &msg->msg_iter,
chunk, &csum))
goto fault;
if (csum_fold(csum)) {
iov_iter_revert(&msg->msg_iter, chunk);
return -EINVAL;
}
if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
!skb->csum_complete_sw)
netdev_rx_csum_fault(NULL, skb);
}
return 0;
fault:
return -EFAULT;
}
EXPORT_SYMBOL(skb_copy_and_csum_datagram_msg);
/**
* 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.
*/
__poll_t datagram_poll(struct file *file, struct socket *sock,
poll_table *wait)
{
struct sock *sk = sock->sk;
__poll_t mask;
u8 shutdown;
sock_poll_wait(file, sock, wait);
mask = 0;
/* exceptional events? */
if (READ_ONCE(sk->sk_err) ||
!skb_queue_empty_lockless(&sk->sk_error_queue))
mask |= EPOLLERR |
(sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? EPOLLPRI : 0);
shutdown = READ_ONCE(sk->sk_shutdown);
if (shutdown & RCV_SHUTDOWN)
mask |= EPOLLRDHUP | EPOLLIN | EPOLLRDNORM;
if (shutdown == SHUTDOWN_MASK)
mask |= EPOLLHUP;
/* readable? */
if (!skb_queue_empty_lockless(&sk->sk_receive_queue))
mask |= EPOLLIN | EPOLLRDNORM;
/* Connection-based need to check for termination and startup */
if (connection_based(sk)) {
int state = READ_ONCE(sk->sk_state);
if (state == TCP_CLOSE)
mask |= EPOLLHUP;
/* connection hasn't started yet? */
if (state == TCP_SYN_SENT)
return mask;
}
/* writable? */
if (sock_writeable(sk))
mask |= EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND;
else
sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
return mask;
}
EXPORT_SYMBOL(datagram_poll);
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