cregit-Linux how code gets into the kernel

Release 4.8 net/core/datagram.c

Directory: net/core
/*
 *      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@lxorguk.ukuu.org.uk>. (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 <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/uio.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>

/*
 *      Is a socket 'connection oriented' ?
 */

static inline int connection_based(struct sock *sk) { return sk->sk_type == SOCK_SEQPACKET || sk->sk_type == SOCK_STREAM; }

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static int receiver_wake_function(wait_queue_t *wait, unsigned int mode, int sync, void *key) { unsigned long bits = (unsigned long)key; /* * Avoid a wakeup if event not interesting for us */ if (bits && !(bits & (POLLIN | POLLERR))) return 0; return autoremove_wake_function(wait, mode, sync, key); }

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/* * Wait for the last received packet to be different from skb */
int __skb_wait_for_more_packets(struct sock *sk, 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 (sk->sk_receive_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; }

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pre-gitpre-git13369.27%1157.89%
linus torvaldslinus torvalds199.90%15.26%
arnaldo carvalho de meloarnaldo carvalho de melo168.33%210.53%
benjamin poirierbenjamin poirier105.21%15.26%
eric dumazeteric dumazet94.69%210.53%
andrew mortonandrew morton42.08%15.26%
rainer weikusatrainer weikusat10.52%15.26%
Total192100.00%19100.00%

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; }

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herbert xuherbert xu112100.00%2100.00%
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/** * __skb_try_recv_datagram - Receive a datagram skbuff * @sk: socket * @flags: MSG_ flags * @peeked: returns non-zero if this packet has been seen before * @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, unsigned int flags, int *peeked, int *off, int *err, struct sk_buff **last) { struct sk_buff_head *queue = &sk->sk_receive_queue; 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) */ int _off = *off; *last = (struct sk_buff *)queue; spin_lock_irqsave(&queue->lock, cpu_flags); skb_queue_walk(queue, skb) { *last = skb; *peeked = skb->peeked; if (flags & MSG_PEEK) { if (_off >= skb->len && (skb->len || _off || skb->peeked)) { _off -= skb->len; continue; } skb = skb_set_peeked(skb); error = PTR_ERR(skb); if (IS_ERR(skb)) { spin_unlock_irqrestore(&queue->lock, cpu_flags); goto no_packet; } atomic_inc(&skb->users); } else __skb_unlink(skb, queue); spin_unlock_irqrestore(&queue->lock, cpu_flags); *off = _off; return skb; } spin_unlock_irqrestore(&queue->lock, cpu_flags); } while (sk_can_busy_loop(sk) && sk_busy_loop(sk, flags & MSG_DONTWAIT)); error = -EAGAIN; no_packet: *err = error; return NULL; }

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pre-gitpre-git6925.75%834.78%
herbert xuherbert xu6323.51%313.04%
pavel emelianovpavel emelianov4115.30%28.70%
rainer weikusatrainer weikusat3613.43%14.35%
benjamin poirierbenjamin poirier3412.69%28.70%
eliezer tamireliezer tamir155.60%28.70%
eric dumazeteric dumazet51.87%28.70%
arnaldo carvalho de meloarnaldo carvalho de melo41.49%28.70%
david shwatrzdavid shwatrz10.37%14.35%
Total268100.00%23100.00%

EXPORT_SYMBOL(__skb_try_recv_datagram);
struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags, int *peeked, 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, flags, peeked, off, err, &last); if (skb) return skb; if (*err != -EAGAIN) break; } while (timeo && !__skb_wait_for_more_packets(sk, err, &timeo, last)); return NULL; }

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rainer weikusatrainer weikusat8578.70%225.00%
pre-gitpre-git2018.52%450.00%
benjamin poirierbenjamin poirier21.85%112.50%
arnaldo carvalho de meloarnaldo carvalho de melo10.93%112.50%
Total108100.00%8100.00%

EXPORT_SYMBOL(__skb_recv_datagram);
struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned int flags, int noblock, int *err) { int peeked, off = 0; return __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0), &peeked, &off, err); }

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herbert xuherbert xu4685.19%133.33%
pavel emelianovpavel emelianov712.96%133.33%
eric dumazeteric dumazet11.85%133.33%
Total54100.00%3100.00%

EXPORT_SYMBOL(skb_recv_datagram);
void skb_free_datagram(struct sock *sk, struct sk_buff *skb) { consume_skb(skb); sk_mem_reclaim_partial(sk); }

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eric dumazeteric dumazet14.00%120.00%
neil hormanneil horman14.00%120.00%
Total25100.00%5100.00%

EXPORT_SYMBOL(skb_free_datagram);
void __skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb, int len) { bool slow; if (likely(atomic_read(&skb->users) == 1)) smp_rmb(); else if (likely(!atomic_dec_and_test(&skb->users))) { sk_peek_offset_bwd(sk, len); return; } slow = lock_sock_fast(sk); sk_peek_offset_bwd(sk, len); skb_orphan(skb); sk_mem_reclaim_partial(sk); unlock_sock_fast(sk, slow); /* skb is now orphaned, can be freed outside of locked section */ __kfree_skb(skb); }

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eric dumazeteric dumazet8180.20%480.00%
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Total101100.00%5100.00%

EXPORT_SYMBOL(__skb_free_datagram_locked); /** * 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 = 0; if (flags & MSG_PEEK) { err = -ENOENT; spin_lock_bh(&sk->sk_receive_queue.lock); if (skb == skb_peek(&sk->sk_receive_queue)) { __skb_unlink(skb, &sk->sk_receive_queue); atomic_dec(&skb->users); err = 0; } spin_unlock_bh(&sk->sk_receive_queue.lock); } kfree_skb(skb); atomic_inc(&sk->sk_drops); sk_mem_reclaim_partial(sk); return err; }

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john dykstrajohn dykstra65.26%116.67%
hideo aokihideo aoki32.63%116.67%
Total114100.00%6100.00%

EXPORT_SYMBOL(skb_kill_datagram); /** * 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) { int start = skb_headlen(skb); int i, copy = start - offset; struct sk_buff *frag_iter; trace_skb_copy_datagram_iovec(skb, len); /* Copy header. */ if (copy > 0) { if (copy > len) copy = len; if (copy_to_iter(skb->data + offset, copy, to) != copy) goto short_copy; 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) { if (copy > len) copy = len; if (copy_page_to_iter(skb_frag_page(frag), frag->page_offset + offset - start, copy, to) != copy) goto short_copy; 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_iter(frag_iter, offset - start, to, copy)) 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: return -EFAULT; short_copy: if (iov_iter_count(to)) goto fault; return 0; }

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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), frag->page_offset + 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; }

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EXPORT_SYMBOL(skb_copy_datagram_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 len = iov_iter_count(from); int copy = min_t(int, skb_headlen(skb), len); int frag = 0; /* copy up to skb headlen */ if (skb_copy_datagram_from_iter(skb, 0, from, copy)) return -EFAULT; while (iov_iter_count(from)) { struct page *pages[MAX_SKB_FRAGS]; size_t start; ssize_t copied; unsigned long truesize; int n = 0; if (frag == MAX_SKB_FRAGS) return -EMSGSIZE; copied = iov_iter_get_pages(from, pages, ~0U, MAX_SKB_FRAGS - frag, &start); if (copied < 0) return -EFAULT; iov_iter_advance(from, copied); truesize = PAGE_ALIGN(copied + start); skb->data_len += copied; skb->len += copied; skb->truesize += truesize; atomic_add(truesize, &skb->sk->sk_wmem_alloc); while (copied) { int size = min_t(int, copied, PAGE_SIZE - start); skb_fill_page_desc(skb, frag++, pages[n], start, size); start = 0; copied -= size; n++; } } return 0; }

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EXPORT_SYMBOL(zerocopy_sg_from_iter);
static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset, struct iov_iter *to, int len, __wsum *csump) { int start = skb_headlen(skb); int i, copy = start - offset; struct sk_buff *frag_iter; int pos = 0; int n; /* Copy header. */ if (copy > 0) { if (copy > len) copy = len; n = csum_and_copy_to_iter(skb->data + offset, copy, csump, to); if (n != copy) goto fault; if ((len -= copy) == 0) return 0; offset += copy; pos = copy; } 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) { __wsum csum2 = 0; struct page *page = skb_frag_page(frag); u8 *vaddr = kmap(page); if (copy > len) copy = len; n = csum_and_copy_to_iter(vaddr + frag->page_offset + offset - start, copy, &csum2, to); kunmap(page); if (n != copy) goto fault; *csump = csum_block_add(*csump, csum2, pos); if (!(len -= copy)) return 0; offset += copy; pos += 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) { __wsum csum2 = 0; if (copy > len) copy = len; if (skb_copy_and_csum_datagram(frag_iter, offset - start, to, copy, &csum2)) goto fault; *csump = csum_block_add(*csump, csum2, pos); if ((len -= copy) == 0) return 0; offset += copy; pos += copy; } start = end; } if (!len) return 0; fault: return -EFAULT; }

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linus torvaldslinus torvalds31573.09%19.09%
david s. millerdavid s. miller4710.90%218.18%
al viroal viro317.19%218.18%
eric dumazeteric dumazet184.18%19.09%
arnaldo carvalho de meloarnaldo carvalho de melo92.09%19.09%
ilpo jarvinenilpo jarvinen40.93%19.09%
james morrisjames morris30.70%19.09%
ian campbellian campbell30.70%19.09%
adrian bunkadrian bunk10.23%19.09%
Total431100.00%11100.00%


__sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len) { __sum16 sum; sum = csum_fold(skb_checksum(skb, 0, len, skb->csum)); if (likely(!sum)) { if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) && !skb->csum_complete_sw) netdev_rx_csum_fault(skb->dev); } if (!skb_shared(skb)) skb->csum_valid = !sum; return sum; }

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herbert xuherbert xu6070.59%337.50%
tom herberttom herbert2225.88%225.00%
al viroal viro22.35%225.00%
patrick mchardypatrick mchardy11.18%112.50%
Total85100.00%8100.00%

EXPORT_SYMBOL(__skb_checksum_complete_head);
__sum16 __skb_checksum_complete(struct sk_buff *skb) { __wsum csum; __sum16 sum; csum = skb_checksum(skb, 0, skb->len, 0); /* skb->csum holds pseudo checksum */ sum = csum_fold(csum_add(skb->csum, csum)); if (likely(!sum)) { if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) && !skb->csum_complete_sw) netdev_rx_csum_fault(skb->dev); } if (!skb_shared(skb)) { /* Save full packet checksum */ skb->csum = csum; skb->ip_summed = CHECKSUM_COMPLETE; skb->csum_complete_sw = 1; skb->csum_valid = !sum; } return sum; }

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tom herberttom herbert9076.27%133.33%
herbert xuherbert xu2823.73%266.67%
Total118100.00%3100.00%

EXPORT_SYMBOL(__skb_checksum_complete); /** * 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)) goto csum_error; 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)) goto csum_error; if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE)) netdev_rx_csum_fault(skb->dev); } return 0; csum_error: return -EINVAL; fault: return -EFAULT; }

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linus torvaldslinus torvalds11673.42%111.11%
herbert xuherbert xu2616.46%222.22%
al viroal viro138.23%333.33%
pre-gitpre-git21.27%222.22%
patrick mchardypatrick mchardy10.63%111.11%
Total158100.00%9100.00%

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. */
unsigned int datagram_poll(struct file *file, struct socket *sock, poll_table *wait) { struct sock *sk =