/net/ipv4/tcp.c
C | 3678 lines | 2450 code | 517 blank | 711 comment | 591 complexity | c197fe294b462b6ba1ba5494f7f82caa MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
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- /*
- * INET An implementation of the TCP/IP protocol suite for the LINUX
- * operating system. INET is implemented using the BSD Socket
- * interface as the means of communication with the user level.
- *
- * Implementation of the Transmission Control Protocol(TCP).
- *
- * Authors: Ross Biro
- * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
- * Mark Evans, <evansmp@uhura.aston.ac.uk>
- * Corey Minyard <wf-rch!minyard@relay.EU.net>
- * Florian La Roche, <flla@stud.uni-sb.de>
- * Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
- * Linus Torvalds, <torvalds@cs.helsinki.fi>
- * Alan Cox, <gw4pts@gw4pts.ampr.org>
- * Matthew Dillon, <dillon@apollo.west.oic.com>
- * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
- * Jorge Cwik, <jorge@laser.satlink.net>
- *
- * Fixes:
- * Alan Cox : Numerous verify_area() calls
- * Alan Cox : Set the ACK bit on a reset
- * Alan Cox : Stopped it crashing if it closed while
- * sk->inuse=1 and was trying to connect
- * (tcp_err()).
- * Alan Cox : All icmp error handling was broken
- * pointers passed where wrong and the
- * socket was looked up backwards. Nobody
- * tested any icmp error code obviously.
- * Alan Cox : tcp_err() now handled properly. It
- * wakes people on errors. poll
- * behaves and the icmp error race
- * has gone by moving it into sock.c
- * Alan Cox : tcp_send_reset() fixed to work for
- * everything not just packets for
- * unknown sockets.
- * Alan Cox : tcp option processing.
- * Alan Cox : Reset tweaked (still not 100%) [Had
- * syn rule wrong]
- * Herp Rosmanith : More reset fixes
- * Alan Cox : No longer acks invalid rst frames.
- * Acking any kind of RST is right out.
- * Alan Cox : Sets an ignore me flag on an rst
- * receive otherwise odd bits of prattle
- * escape still
- * Alan Cox : Fixed another acking RST frame bug.
- * Should stop LAN workplace lockups.
- * Alan Cox : Some tidyups using the new skb list
- * facilities
- * Alan Cox : sk->keepopen now seems to work
- * Alan Cox : Pulls options out correctly on accepts
- * Alan Cox : Fixed assorted sk->rqueue->next errors
- * Alan Cox : PSH doesn't end a TCP read. Switched a
- * bit to skb ops.
- * Alan Cox : Tidied tcp_data to avoid a potential
- * nasty.
- * Alan Cox : Added some better commenting, as the
- * tcp is hard to follow
- * Alan Cox : Removed incorrect check for 20 * psh
- * Michael O'Reilly : ack < copied bug fix.
- * Johannes Stille : Misc tcp fixes (not all in yet).
- * Alan Cox : FIN with no memory -> CRASH
- * Alan Cox : Added socket option proto entries.
- * Also added awareness of them to accept.
- * Alan Cox : Added TCP options (SOL_TCP)
- * Alan Cox : Switched wakeup calls to callbacks,
- * so the kernel can layer network
- * sockets.
- * Alan Cox : Use ip_tos/ip_ttl settings.
- * Alan Cox : Handle FIN (more) properly (we hope).
- * Alan Cox : RST frames sent on unsynchronised
- * state ack error.
- * Alan Cox : Put in missing check for SYN bit.
- * Alan Cox : Added tcp_select_window() aka NET2E
- * window non shrink trick.
- * Alan Cox : Added a couple of small NET2E timer
- * fixes
- * Charles Hedrick : TCP fixes
- * Toomas Tamm : TCP window fixes
- * Alan Cox : Small URG fix to rlogin ^C ack fight
- * Charles Hedrick : Rewrote most of it to actually work
- * Linus : Rewrote tcp_read() and URG handling
- * completely
- * Gerhard Koerting: Fixed some missing timer handling
- * Matthew Dillon : Reworked TCP machine states as per RFC
- * Gerhard Koerting: PC/TCP workarounds
- * Adam Caldwell : Assorted timer/timing errors
- * Matthew Dillon : Fixed another RST bug
- * Alan Cox : Move to kernel side addressing changes.
- * Alan Cox : Beginning work on TCP fastpathing
- * (not yet usable)
- * Arnt Gulbrandsen: Turbocharged tcp_check() routine.
- * Alan Cox : TCP fast path debugging
- * Alan Cox : Window clamping
- * Michael Riepe : Bug in tcp_check()
- * Matt Dillon : More TCP improvements and RST bug fixes
- * Matt Dillon : Yet more small nasties remove from the
- * TCP code (Be very nice to this man if
- * tcp finally works 100%) 8)
- * Alan Cox : BSD accept semantics.
- * Alan Cox : Reset on closedown bug.
- * Peter De Schrijver : ENOTCONN check missing in tcp_sendto().
- * Michael Pall : Handle poll() after URG properly in
- * all cases.
- * Michael Pall : Undo the last fix in tcp_read_urg()
- * (multi URG PUSH broke rlogin).
- * Michael Pall : Fix the multi URG PUSH problem in
- * tcp_readable(), poll() after URG
- * works now.
- * Michael Pall : recv(...,MSG_OOB) never blocks in the
- * BSD api.
- * Alan Cox : Changed the semantics of sk->socket to
- * fix a race and a signal problem with
- * accept() and async I/O.
- * Alan Cox : Relaxed the rules on tcp_sendto().
- * Yury Shevchuk : Really fixed accept() blocking problem.
- * Craig I. Hagan : Allow for BSD compatible TIME_WAIT for
- * clients/servers which listen in on
- * fixed ports.
- * Alan Cox : Cleaned the above up and shrank it to
- * a sensible code size.
- * Alan Cox : Self connect lockup fix.
- * Alan Cox : No connect to multicast.
- * Ross Biro : Close unaccepted children on master
- * socket close.
- * Alan Cox : Reset tracing code.
- * Alan Cox : Spurious resets on shutdown.
- * Alan Cox : Giant 15 minute/60 second timer error
- * Alan Cox : Small whoops in polling before an
- * accept.
- * Alan Cox : Kept the state trace facility since
- * it's handy for debugging.
- * Alan Cox : More reset handler fixes.
- * Alan Cox : Started rewriting the code based on
- * the RFC's for other useful protocol
- * references see: Comer, KA9Q NOS, and
- * for a reference on the difference
- * between specifications and how BSD
- * works see the 4.4lite source.
- * A.N.Kuznetsov : Don't time wait on completion of tidy
- * close.
- * Linus Torvalds : Fin/Shutdown & copied_seq changes.
- * Linus Torvalds : Fixed BSD port reuse to work first syn
- * Alan Cox : Reimplemented timers as per the RFC
- * and using multiple timers for sanity.
- * Alan Cox : Small bug fixes, and a lot of new
- * comments.
- * Alan Cox : Fixed dual reader crash by locking
- * the buffers (much like datagram.c)
- * Alan Cox : Fixed stuck sockets in probe. A probe
- * now gets fed up of retrying without
- * (even a no space) answer.
- * Alan Cox : Extracted closing code better
- * Alan Cox : Fixed the closing state machine to
- * resemble the RFC.
- * Alan Cox : More 'per spec' fixes.
- * Jorge Cwik : Even faster checksumming.
- * Alan Cox : tcp_data() doesn't ack illegal PSH
- * only frames. At least one pc tcp stack
- * generates them.
- * Alan Cox : Cache last socket.
- * Alan Cox : Per route irtt.
- * Matt Day : poll()->select() match BSD precisely on error
- * Alan Cox : New buffers
- * Marc Tamsky : Various sk->prot->retransmits and
- * sk->retransmits misupdating fixed.
- * Fixed tcp_write_timeout: stuck close,
- * and TCP syn retries gets used now.
- * Mark Yarvis : In tcp_read_wakeup(), don't send an
- * ack if state is TCP_CLOSED.
- * Alan Cox : Look up device on a retransmit - routes may
- * change. Doesn't yet cope with MSS shrink right
- * but it's a start!
- * Marc Tamsky : Closing in closing fixes.
- * Mike Shaver : RFC1122 verifications.
- * Alan Cox : rcv_saddr errors.
- * Alan Cox : Block double connect().
- * Alan Cox : Small hooks for enSKIP.
- * Alexey Kuznetsov: Path MTU discovery.
- * Alan Cox : Support soft errors.
- * Alan Cox : Fix MTU discovery pathological case
- * when the remote claims no mtu!
- * Marc Tamsky : TCP_CLOSE fix.
- * Colin (G3TNE) : Send a reset on syn ack replies in
- * window but wrong (fixes NT lpd problems)
- * Pedro Roque : Better TCP window handling, delayed ack.
- * Joerg Reuter : No modification of locked buffers in
- * tcp_do_retransmit()
- * Eric Schenk : Changed receiver side silly window
- * avoidance algorithm to BSD style
- * algorithm. This doubles throughput
- * against machines running Solaris,
- * and seems to result in general
- * improvement.
- * Stefan Magdalinski : adjusted tcp_readable() to fix FIONREAD
- * Willy Konynenberg : Transparent proxying support.
- * Mike McLagan : Routing by source
- * Keith Owens : Do proper merging with partial SKB's in
- * tcp_do_sendmsg to avoid burstiness.
- * Eric Schenk : Fix fast close down bug with
- * shutdown() followed by close().
- * Andi Kleen : Make poll agree with SIGIO
- * Salvatore Sanfilippo : Support SO_LINGER with linger == 1 and
- * lingertime == 0 (RFC 793 ABORT Call)
- * Hirokazu Takahashi : Use copy_from_user() instead of
- * csum_and_copy_from_user() if possible.
- *
- * 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.
- *
- * Description of States:
- *
- * TCP_SYN_SENT sent a connection request, waiting for ack
- *
- * TCP_SYN_RECV received a connection request, sent ack,
- * waiting for final ack in three-way handshake.
- *
- * TCP_ESTABLISHED connection established
- *
- * TCP_FIN_WAIT1 our side has shutdown, waiting to complete
- * transmission of remaining buffered data
- *
- * TCP_FIN_WAIT2 all buffered data sent, waiting for remote
- * to shutdown
- *
- * TCP_CLOSING both sides have shutdown but we still have
- * data we have to finish sending
- *
- * TCP_TIME_WAIT timeout to catch resent junk before entering
- * closed, can only be entered from FIN_WAIT2
- * or CLOSING. Required because the other end
- * may not have gotten our last ACK causing it
- * to retransmit the data packet (which we ignore)
- *
- * TCP_CLOSE_WAIT remote side has shutdown and is waiting for
- * us to finish writing our data and to shutdown
- * (we have to close() to move on to LAST_ACK)
- *
- * TCP_LAST_ACK out side has shutdown after remote has
- * shutdown. There may still be data in our
- * buffer that we have to finish sending
- *
- * TCP_CLOSE socket is finished
- */
- #define pr_fmt(fmt) "TCP: " fmt
- #include <linux/kernel.h>
- #include <linux/module.h>
- #include <linux/types.h>
- #include <linux/fcntl.h>
- #include <linux/poll.h>
- #include <linux/init.h>
- #include <linux/fs.h>
- #include <linux/skbuff.h>
- #include <linux/scatterlist.h>
- #include <linux/splice.h>
- #include <linux/net.h>
- #include <linux/socket.h>
- #include <linux/random.h>
- #include <linux/bootmem.h>
- #include <linux/highmem.h>
- #include <linux/swap.h>
- #include <linux/cache.h>
- #include <linux/err.h>
- #include <linux/crypto.h>
- #include <linux/time.h>
- #include <linux/slab.h>
- #include <net/icmp.h>
- #include <net/inet_common.h>
- #include <net/tcp.h>
- #include <net/xfrm.h>
- #include <net/ip.h>
- #include <net/netdma.h>
- #include <net/sock.h>
- #include <asm/uaccess.h>
- #include <asm/ioctls.h>
- int sysctl_tcp_fin_timeout __read_mostly = TCP_FIN_TIMEOUT;
- struct percpu_counter tcp_orphan_count;
- EXPORT_SYMBOL_GPL(tcp_orphan_count);
- int sysctl_tcp_wmem[3] __read_mostly;
- int sysctl_tcp_rmem[3] __read_mostly;
- EXPORT_SYMBOL(sysctl_tcp_rmem);
- EXPORT_SYMBOL(sysctl_tcp_wmem);
- atomic_long_t tcp_memory_allocated; /* Current allocated memory. */
- EXPORT_SYMBOL(tcp_memory_allocated);
- /*
- * Current number of TCP sockets.
- */
- struct percpu_counter tcp_sockets_allocated;
- EXPORT_SYMBOL(tcp_sockets_allocated);
- /*
- * TCP splice context
- */
- struct tcp_splice_state {
- struct pipe_inode_info *pipe;
- size_t len;
- unsigned int flags;
- };
- /*
- * Pressure flag: try to collapse.
- * Technical note: it is used by multiple contexts non atomically.
- * All the __sk_mem_schedule() is of this nature: accounting
- * is strict, actions are advisory and have some latency.
- */
- int tcp_memory_pressure __read_mostly;
- EXPORT_SYMBOL(tcp_memory_pressure);
- void tcp_enter_memory_pressure(struct sock *sk)
- {
- if (!tcp_memory_pressure) {
- NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMEMORYPRESSURES);
- tcp_memory_pressure = 1;
- }
- }
- EXPORT_SYMBOL(tcp_enter_memory_pressure);
- /* Convert seconds to retransmits based on initial and max timeout */
- static u8 secs_to_retrans(int seconds, int timeout, int rto_max)
- {
- u8 res = 0;
- if (seconds > 0) {
- int period = timeout;
- res = 1;
- while (seconds > period && res < 255) {
- res++;
- timeout <<= 1;
- if (timeout > rto_max)
- timeout = rto_max;
- period += timeout;
- }
- }
- return res;
- }
- /* Convert retransmits to seconds based on initial and max timeout */
- static int retrans_to_secs(u8 retrans, int timeout, int rto_max)
- {
- int period = 0;
- if (retrans > 0) {
- period = timeout;
- while (--retrans) {
- timeout <<= 1;
- if (timeout > rto_max)
- timeout = rto_max;
- period += timeout;
- }
- }
- return period;
- }
- /* Address-family independent initialization for a tcp_sock.
- *
- * NOTE: A lot of things set to zero explicitly by call to
- * sk_alloc() so need not be done here.
- */
- void tcp_init_sock(struct sock *sk)
- {
- struct inet_connection_sock *icsk = inet_csk(sk);
- struct tcp_sock *tp = tcp_sk(sk);
- skb_queue_head_init(&tp->out_of_order_queue);
- tcp_init_xmit_timers(sk);
- tcp_prequeue_init(tp);
- INIT_LIST_HEAD(&tp->tsq_node);
- icsk->icsk_rto = TCP_TIMEOUT_INIT;
- tp->mdev = TCP_TIMEOUT_INIT;
- /* So many TCP implementations out there (incorrectly) count the
- * initial SYN frame in their delayed-ACK and congestion control
- * algorithms that we must have the following bandaid to talk
- * efficiently to them. -DaveM
- */
- tp->snd_cwnd = TCP_INIT_CWND;
- /* See draft-stevens-tcpca-spec-01 for discussion of the
- * initialization of these values.
- */
- tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
- tp->snd_cwnd_clamp = ~0;
- tp->mss_cache = TCP_MSS_DEFAULT;
- tp->reordering = sysctl_tcp_reordering;
- tcp_enable_early_retrans(tp);
- icsk->icsk_ca_ops = &tcp_init_congestion_ops;
- tp->tsoffset = 0;
- sk->sk_state = TCP_CLOSE;
- sk->sk_write_space = sk_stream_write_space;
- sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
- icsk->icsk_sync_mss = tcp_sync_mss;
- /* TCP Cookie Transactions */
- if (sysctl_tcp_cookie_size > 0) {
- /* Default, cookies without s_data_payload. */
- tp->cookie_values =
- kzalloc(sizeof(*tp->cookie_values),
- sk->sk_allocation);
- if (tp->cookie_values != NULL)
- kref_init(&tp->cookie_values->kref);
- }
- /* Presumed zeroed, in order of appearance:
- * cookie_in_always, cookie_out_never,
- * s_data_constant, s_data_in, s_data_out
- */
- sk->sk_sndbuf = sysctl_tcp_wmem[1];
- sk->sk_rcvbuf = sysctl_tcp_rmem[1];
- local_bh_disable();
- sock_update_memcg(sk);
- sk_sockets_allocated_inc(sk);
- local_bh_enable();
- }
- EXPORT_SYMBOL(tcp_init_sock);
- /*
- * Wait for a TCP event.
- *
- * Note that we don't need to lock the socket, as the upper poll layers
- * take care of normal races (between the test and the event) and we don't
- * go look at any of the socket buffers directly.
- */
- unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
- {
- unsigned int mask;
- struct sock *sk = sock->sk;
- const struct tcp_sock *tp = tcp_sk(sk);
- sock_poll_wait(file, sk_sleep(sk), wait);
- if (sk->sk_state == TCP_LISTEN)
- return inet_csk_listen_poll(sk);
- /* Socket is not locked. We are protected from async events
- * by poll logic and correct handling of state changes
- * made by other threads is impossible in any case.
- */
- mask = 0;
- /*
- * POLLHUP is certainly not done right. But poll() doesn't
- * have a notion of HUP in just one direction, and for a
- * socket the read side is more interesting.
- *
- * Some poll() documentation says that POLLHUP is incompatible
- * with the POLLOUT/POLLWR flags, so somebody should check this
- * all. But careful, it tends to be safer to return too many
- * bits than too few, and you can easily break real applications
- * if you don't tell them that something has hung up!
- *
- * Check-me.
- *
- * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and
- * our fs/select.c). It means that after we received EOF,
- * poll always returns immediately, making impossible poll() on write()
- * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP
- * if and only if shutdown has been made in both directions.
- * Actually, it is interesting to look how Solaris and DUX
- * solve this dilemma. I would prefer, if POLLHUP were maskable,
- * then we could set it on SND_SHUTDOWN. BTW examples given
- * in Stevens' books assume exactly this behaviour, it explains
- * why POLLHUP is incompatible with POLLOUT. --ANK
- *
- * NOTE. Check for TCP_CLOSE is added. The goal is to prevent
- * blocking on fresh not-connected or disconnected socket. --ANK
- */
- if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == TCP_CLOSE)
- mask |= POLLHUP;
- if (sk->sk_shutdown & RCV_SHUTDOWN)
- mask |= POLLIN | POLLRDNORM | POLLRDHUP;
- /* Connected or passive Fast Open socket? */
- if (sk->sk_state != TCP_SYN_SENT &&
- (sk->sk_state != TCP_SYN_RECV || tp->fastopen_rsk != NULL)) {
- int target = sock_rcvlowat(sk, 0, INT_MAX);
- if (tp->urg_seq == tp->copied_seq &&
- !sock_flag(sk, SOCK_URGINLINE) &&
- tp->urg_data)
- target++;
- /* Potential race condition. If read of tp below will
- * escape above sk->sk_state, we can be illegally awaken
- * in SYN_* states. */
- if (tp->rcv_nxt - tp->copied_seq >= target)
- mask |= POLLIN | POLLRDNORM;
- if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
- if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
- mask |= POLLOUT | POLLWRNORM;
- } else { /* send SIGIO later */
- set_bit(SOCK_ASYNC_NOSPACE,
- &sk->sk_socket->flags);
- set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
- /* Race breaker. If space is freed after
- * wspace test but before the flags are set,
- * IO signal will be lost.
- */
- if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk))
- mask |= POLLOUT | POLLWRNORM;
- }
- } else
- mask |= POLLOUT | POLLWRNORM;
- if (tp->urg_data & TCP_URG_VALID)
- mask |= POLLPRI;
- }
- /* This barrier is coupled with smp_wmb() in tcp_reset() */
- smp_rmb();
- if (sk->sk_err)
- mask |= POLLERR;
- return mask;
- }
- EXPORT_SYMBOL(tcp_poll);
- int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
- {
- struct tcp_sock *tp = tcp_sk(sk);
- int answ;
- bool slow;
- switch (cmd) {
- case SIOCINQ:
- if (sk->sk_state == TCP_LISTEN)
- return -EINVAL;
- slow = lock_sock_fast(sk);
- if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
- answ = 0;
- else if (sock_flag(sk, SOCK_URGINLINE) ||
- !tp->urg_data ||
- before(tp->urg_seq, tp->copied_seq) ||
- !before(tp->urg_seq, tp->rcv_nxt)) {
- answ = tp->rcv_nxt - tp->copied_seq;
- /* Subtract 1, if FIN was received */
- if (answ && sock_flag(sk, SOCK_DONE))
- answ--;
- } else
- answ = tp->urg_seq - tp->copied_seq;
- unlock_sock_fast(sk, slow);
- break;
- case SIOCATMARK:
- answ = tp->urg_data && tp->urg_seq == tp->copied_seq;
- break;
- case SIOCOUTQ:
- if (sk->sk_state == TCP_LISTEN)
- return -EINVAL;
- if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
- answ = 0;
- else
- answ = tp->write_seq - tp->snd_una;
- break;
- case SIOCOUTQNSD:
- if (sk->sk_state == TCP_LISTEN)
- return -EINVAL;
- if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
- answ = 0;
- else
- answ = tp->write_seq - tp->snd_nxt;
- break;
- default:
- return -ENOIOCTLCMD;
- }
- return put_user(answ, (int __user *)arg);
- }
- EXPORT_SYMBOL(tcp_ioctl);
- static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
- {
- TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH;
- tp->pushed_seq = tp->write_seq;
- }
- static inline bool forced_push(const struct tcp_sock *tp)
- {
- return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
- }
- static inline void skb_entail(struct sock *sk, struct sk_buff *skb)
- {
- struct tcp_sock *tp = tcp_sk(sk);
- struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
- skb->csum = 0;
- tcb->seq = tcb->end_seq = tp->write_seq;
- tcb->tcp_flags = TCPHDR_ACK;
- tcb->sacked = 0;
- skb_header_release(skb);
- tcp_add_write_queue_tail(sk, skb);
- sk->sk_wmem_queued += skb->truesize;
- sk_mem_charge(sk, skb->truesize);
- if (tp->nonagle & TCP_NAGLE_PUSH)
- tp->nonagle &= ~TCP_NAGLE_PUSH;
- }
- static inline void tcp_mark_urg(struct tcp_sock *tp, int flags)
- {
- if (flags & MSG_OOB)
- tp->snd_up = tp->write_seq;
- }
- static inline void tcp_push(struct sock *sk, int flags, int mss_now,
- int nonagle)
- {
- if (tcp_send_head(sk)) {
- struct tcp_sock *tp = tcp_sk(sk);
- if (!(flags & MSG_MORE) || forced_push(tp))
- tcp_mark_push(tp, tcp_write_queue_tail(sk));
- tcp_mark_urg(tp, flags);
- __tcp_push_pending_frames(sk, mss_now,
- (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle);
- }
- }
- static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
- unsigned int offset, size_t len)
- {
- struct tcp_splice_state *tss = rd_desc->arg.data;
- int ret;
- ret = skb_splice_bits(skb, offset, tss->pipe, min(rd_desc->count, len),
- tss->flags);
- if (ret > 0)
- rd_desc->count -= ret;
- return ret;
- }
- static int __tcp_splice_read(struct sock *sk, struct tcp_splice_state *tss)
- {
- /* Store TCP splice context information in read_descriptor_t. */
- read_descriptor_t rd_desc = {
- .arg.data = tss,
- .count = tss->len,
- };
- return tcp_read_sock(sk, &rd_desc, tcp_splice_data_recv);
- }
- /**
- * tcp_splice_read - splice data from TCP socket to a pipe
- * @sock: socket to splice from
- * @ppos: position (not valid)
- * @pipe: pipe to splice to
- * @len: number of bytes to splice
- * @flags: splice modifier flags
- *
- * Description:
- * Will read pages from given socket and fill them into a pipe.
- *
- **/
- ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
- struct pipe_inode_info *pipe, size_t len,
- unsigned int flags)
- {
- struct sock *sk = sock->sk;
- struct tcp_splice_state tss = {
- .pipe = pipe,
- .len = len,
- .flags = flags,
- };
- long timeo;
- ssize_t spliced;
- int ret;
- sock_rps_record_flow(sk);
- /*
- * We can't seek on a socket input
- */
- if (unlikely(*ppos))
- return -ESPIPE;
- ret = spliced = 0;
- lock_sock(sk);
- timeo = sock_rcvtimeo(sk, sock->file->f_flags & O_NONBLOCK);
- while (tss.len) {
- ret = __tcp_splice_read(sk, &tss);
- if (ret < 0)
- break;
- else if (!ret) {
- if (spliced)
- break;
- if (sock_flag(sk, SOCK_DONE))
- break;
- if (sk->sk_err) {
- ret = sock_error(sk);
- break;
- }
- if (sk->sk_shutdown & RCV_SHUTDOWN)
- break;
- if (sk->sk_state == TCP_CLOSE) {
- /*
- * This occurs when user tries to read
- * from never connected socket.
- */
- if (!sock_flag(sk, SOCK_DONE))
- ret = -ENOTCONN;
- break;
- }
- if (!timeo) {
- ret = -EAGAIN;
- break;
- }
- sk_wait_data(sk, &timeo);
- if (signal_pending(current)) {
- ret = sock_intr_errno(timeo);
- break;
- }
- continue;
- }
- tss.len -= ret;
- spliced += ret;
- if (!timeo)
- break;
- release_sock(sk);
- lock_sock(sk);
- if (sk->sk_err || sk->sk_state == TCP_CLOSE ||
- (sk->sk_shutdown & RCV_SHUTDOWN) ||
- signal_pending(current))
- break;
- }
- release_sock(sk);
- if (spliced)
- return spliced;
- return ret;
- }
- EXPORT_SYMBOL(tcp_splice_read);
- struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp)
- {
- struct sk_buff *skb;
- /* The TCP header must be at least 32-bit aligned. */
- size = ALIGN(size, 4);
- skb = alloc_skb_fclone(size + sk->sk_prot->max_header, gfp);
- if (skb) {
- if (sk_wmem_schedule(sk, skb->truesize)) {
- skb_reserve(skb, sk->sk_prot->max_header);
- /*
- * Make sure that we have exactly size bytes
- * available to the caller, no more, no less.
- */
- skb->reserved_tailroom = skb->end - skb->tail - size;
- return skb;
- }
- __kfree_skb(skb);
- } else {
- sk->sk_prot->enter_memory_pressure(sk);
- sk_stream_moderate_sndbuf(sk);
- }
- return NULL;
- }
- static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
- int large_allowed)
- {
- struct tcp_sock *tp = tcp_sk(sk);
- u32 xmit_size_goal, old_size_goal;
- xmit_size_goal = mss_now;
- if (large_allowed && sk_can_gso(sk)) {
- xmit_size_goal = ((sk->sk_gso_max_size - 1) -
- inet_csk(sk)->icsk_af_ops->net_header_len -
- inet_csk(sk)->icsk_ext_hdr_len -
- tp->tcp_header_len);
- /* TSQ : try to have two TSO segments in flight */
- xmit_size_goal = min_t(u32, xmit_size_goal,
- sysctl_tcp_limit_output_bytes >> 1);
- xmit_size_goal = tcp_bound_to_half_wnd(tp, xmit_size_goal);
- /* We try hard to avoid divides here */
- old_size_goal = tp->xmit_size_goal_segs * mss_now;
- if (likely(old_size_goal <= xmit_size_goal &&
- old_size_goal + mss_now > xmit_size_goal)) {
- xmit_size_goal = old_size_goal;
- } else {
- tp->xmit_size_goal_segs =
- min_t(u16, xmit_size_goal / mss_now,
- sk->sk_gso_max_segs);
- xmit_size_goal = tp->xmit_size_goal_segs * mss_now;
- }
- }
- return max(xmit_size_goal, mss_now);
- }
- static int tcp_send_mss(struct sock *sk, int *size_goal, int flags)
- {
- int mss_now;
- mss_now = tcp_current_mss(sk);
- *size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
- return mss_now;
- }
- static ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
- size_t size, int flags)
- {
- struct tcp_sock *tp = tcp_sk(sk);
- int mss_now, size_goal;
- int err;
- ssize_t copied;
- long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
- /* Wait for a connection to finish. One exception is TCP Fast Open
- * (passive side) where data is allowed to be sent before a connection
- * is fully established.
- */
- if (((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) &&
- !tcp_passive_fastopen(sk)) {
- if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
- goto out_err;
- }
- clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
- mss_now = tcp_send_mss(sk, &size_goal, flags);
- copied = 0;
- err = -EPIPE;
- if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
- goto out_err;
- while (size > 0) {
- struct sk_buff *skb = tcp_write_queue_tail(sk);
- int copy, i;
- bool can_coalesce;
- if (!tcp_send_head(sk) || (copy = size_goal - skb->len) <= 0) {
- new_segment:
- if (!sk_stream_memory_free(sk))
- goto wait_for_sndbuf;
- skb = sk_stream_alloc_skb(sk, 0, sk->sk_allocation);
- if (!skb)
- goto wait_for_memory;
- skb_entail(sk, skb);
- copy = size_goal;
- }
- if (copy > size)
- copy = size;
- i = skb_shinfo(skb)->nr_frags;
- can_coalesce = skb_can_coalesce(skb, i, page, offset);
- if (!can_coalesce && i >= MAX_SKB_FRAGS) {
- tcp_mark_push(tp, skb);
- goto new_segment;
- }
- if (!sk_wmem_schedule(sk, copy))
- goto wait_for_memory;
- if (can_coalesce) {
- skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
- } else {
- get_page(page);
- skb_fill_page_desc(skb, i, page, offset, copy);
- }
- skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
- skb->len += copy;
- skb->data_len += copy;
- skb->truesize += copy;
- sk->sk_wmem_queued += copy;
- sk_mem_charge(sk, copy);
- skb->ip_summed = CHECKSUM_PARTIAL;
- tp->write_seq += copy;
- TCP_SKB_CB(skb)->end_seq += copy;
- skb_shinfo(skb)->gso_segs = 0;
- if (!copied)
- TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
- copied += copy;
- offset += copy;
- if (!(size -= copy))
- goto out;
- if (skb->len < size_goal || (flags & MSG_OOB))
- continue;
- if (forced_push(tp)) {
- tcp_mark_push(tp, skb);
- __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
- } else if (skb == tcp_send_head(sk))
- tcp_push_one(sk, mss_now);
- continue;
- wait_for_sndbuf:
- set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
- wait_for_memory:
- tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
- if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
- goto do_error;
- mss_now = tcp_send_mss(sk, &size_goal, flags);
- }
- out:
- if (copied && !(flags & MSG_SENDPAGE_NOTLAST))
- tcp_push(sk, flags, mss_now, tp->nonagle);
- return copied;
- do_error:
- if (copied)
- goto out;
- out_err:
- return sk_stream_error(sk, flags, err);
- }
- int tcp_sendpage(struct sock *sk, struct page *page, int offset,
- size_t size, int flags)
- {
- ssize_t res;
- if (!(sk->sk_route_caps & NETIF_F_SG) ||
- !(sk->sk_route_caps & NETIF_F_ALL_CSUM))
- return sock_no_sendpage(sk->sk_socket, page, offset, size,
- flags);
- lock_sock(sk);
- res = do_tcp_sendpages(sk, page, offset, size, flags);
- release_sock(sk);
- return res;
- }
- EXPORT_SYMBOL(tcp_sendpage);
- static inline int select_size(const struct sock *sk, bool sg)
- {
- const struct tcp_sock *tp = tcp_sk(sk);
- int tmp = tp->mss_cache;
- if (sg) {
- if (sk_can_gso(sk)) {
- /* Small frames wont use a full page:
- * Payload will immediately follow tcp header.
- */
- tmp = SKB_WITH_OVERHEAD(2048 - MAX_TCP_HEADER);
- } else {
- int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
- if (tmp >= pgbreak &&
- tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
- tmp = pgbreak;
- }
- }
- return tmp;
- }
- void tcp_free_fastopen_req(struct tcp_sock *tp)
- {
- if (tp->fastopen_req != NULL) {
- kfree(tp->fastopen_req);
- tp->fastopen_req = NULL;
- }
- }
- static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, int *size)
- {
- struct tcp_sock *tp = tcp_sk(sk);
- int err, flags;
- if (!(sysctl_tcp_fastopen & TFO_CLIENT_ENABLE))
- return -EOPNOTSUPP;
- if (tp->fastopen_req != NULL)
- return -EALREADY; /* Another Fast Open is in progress */
- tp->fastopen_req = kzalloc(sizeof(struct tcp_fastopen_request),
- sk->sk_allocation);
- if (unlikely(tp->fastopen_req == NULL))
- return -ENOBUFS;
- tp->fastopen_req->data = msg;
- flags = (msg->msg_flags & MSG_DONTWAIT) ? O_NONBLOCK : 0;
- err = __inet_stream_connect(sk->sk_socket, msg->msg_name,
- msg->msg_namelen, flags);
- *size = tp->fastopen_req->copied;
- tcp_free_fastopen_req(tp);
- return err;
- }
- int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
- size_t size)
- {
- struct iovec *iov;
- struct tcp_sock *tp = tcp_sk(sk);
- struct sk_buff *skb;
- int iovlen, flags, err, copied = 0;
- int mss_now = 0, size_goal, copied_syn = 0, offset = 0;
- bool sg;
- long timeo;
- lock_sock(sk);
- flags = msg->msg_flags;
- if (flags & MSG_FASTOPEN) {
- err = tcp_sendmsg_fastopen(sk, msg, &copied_syn);
- if (err == -EINPROGRESS && copied_syn > 0)
- goto out;
- else if (err)
- goto out_err;
- offset = copied_syn;
- }
- timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
- /* Wait for a connection to finish. One exception is TCP Fast Open
- * (passive side) where data is allowed to be sent before a connection
- * is fully established.
- */
- if (((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) &&
- !tcp_passive_fastopen(sk)) {
- if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
- goto do_error;
- }
- if (unlikely(tp->repair)) {
- if (tp->repair_queue == TCP_RECV_QUEUE) {
- copied = tcp_send_rcvq(sk, msg, size);
- goto out;
- }
- err = -EINVAL;
- if (tp->repair_queue == TCP_NO_QUEUE)
- goto out_err;
- /* 'common' sending to sendq */
- }
- /* This should be in poll */
- clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
- mss_now = tcp_send_mss(sk, &size_goal, flags);
- /* Ok commence sending. */
- iovlen = msg->msg_iovlen;
- iov = msg->msg_iov;
- copied = 0;
- err = -EPIPE;
- if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
- goto out_err;
- sg = !!(sk->sk_route_caps & NETIF_F_SG);
- while (--iovlen >= 0) {
- size_t seglen = iov->iov_len;
- unsigned char __user *from = iov->iov_base;
- iov++;
- if (unlikely(offset > 0)) { /* Skip bytes copied in SYN */
- if (offset >= seglen) {
- offset -= seglen;
- continue;
- }
- seglen -= offset;
- from += offset;
- offset = 0;
- }
- while (seglen > 0) {
- int copy = 0;
- int max = size_goal;
- skb = tcp_write_queue_tail(sk);
- if (tcp_send_head(sk)) {
- if (skb->ip_summed == CHECKSUM_NONE)
- max = mss_now;
- copy = max - skb->len;
- }
- if (copy <= 0) {
- new_segment:
- /* Allocate new segment. If the interface is SG,
- * allocate skb fitting to single page.
- */
- if (!sk_stream_memory_free(sk))
- goto wait_for_sndbuf;
- skb = sk_stream_alloc_skb(sk,
- select_size(sk, sg),
- sk->sk_allocation);
- if (!skb)
- goto wait_for_memory;
- /*
- * Check whether we can use HW checksum.
- */
- if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
- skb->ip_summed = CHECKSUM_PARTIAL;
- skb_entail(sk, skb);
- copy = size_goal;
- max = size_goal;
- }
- /* Try to append data to the end of skb. */
- if (copy > seglen)
- copy = seglen;
- /* Where to copy to? */
- if (skb_availroom(skb) > 0) {
- /* We have some space in skb head. Superb! */
- copy = min_t(int, copy, skb_availroom(skb));
- err = skb_add_data_nocache(sk, skb, from, copy);
- if (err)
- goto do_fault;
- } else {
- bool merge = true;
- int i = skb_shinfo(skb)->nr_frags;
- struct page_frag *pfrag = sk_page_frag(sk);
- if (!sk_page_frag_refill(sk, pfrag))
- goto wait_for_memory;
- if (!skb_can_coalesce(skb, i, pfrag->page,
- pfrag->offset)) {
- if (i == MAX_SKB_FRAGS || !sg) {
- tcp_mark_push(tp, skb);
- goto new_segment;
- }
- merge = false;
- }
- copy = min_t(int, copy, pfrag->size - pfrag->offset);
- if (!sk_wmem_schedule(sk, copy))
- goto wait_for_memory;
- err = skb_copy_to_page_nocache(sk, from, skb,
- pfrag->page,
- pfrag->offset,
- copy);
- if (err)
- goto do_error;
- /* Update the skb. */
- if (merge) {
- skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
- } else {
- skb_fill_page_desc(skb, i, pfrag->page,
- pfrag->offset, copy);
- get_page(pfrag->page);
- }
- pfrag->offset += copy;
- }
- if (!copied)
- TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
- tp->write_seq += copy;
- TCP_SKB_CB(skb)->end_seq += copy;
- skb_shinfo(skb)->gso_segs = 0;
- from += copy;
- copied += copy;
- if ((seglen -= copy) == 0 && iovlen == 0)
- goto out;
- if (skb->len < max || (flags & MSG_OOB) || unlikely(tp->repair))
- continue;
- if (forced_push(tp)) {
- tcp_mark_push(tp, skb);
- __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
- } else if (skb == tcp_send_head(sk))
- tcp_push_one(sk, mss_now);
- continue;
- wait_for_sndbuf:
- set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
- wait_for_memory:
- if (copied)
- tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
- if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
- goto do_error;
- mss_now = tcp_send_mss(sk, &size_goal, flags);
- }
- }
- out:
- if (copied)
- tcp_push(sk, flags, mss_now, tp->nonagle);
- release_sock(sk);
- return copied + copied_syn;
- do_fault:
- if (!skb->len) {
- tcp_unlink_write_queue(skb, sk);
- /* It is the one place in all of TCP, except connection
- * reset, where we can be unlinking the send_head.
- */
- tcp_check_send_head(sk, skb);
- sk_wmem_free_skb(sk, skb);
- }
- do_error:
- if (copied + copied_syn)
- goto out;
- out_err:
- err = sk_stream_error(sk, flags, err);
- release_sock(sk);
- return err;
- }
- EXPORT_SYMBOL(tcp_sendmsg);
- /*
- * Handle reading urgent data. BSD has very simple semantics for
- * this, no blocking and very strange errors 8)
- */
- static int tcp_recv_urg(struct sock *sk, struct msghdr *msg, int len, int flags)
- {
- struct tcp_sock *tp = tcp_sk(sk);
- /* No URG data to read. */
- if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
- tp->urg_data == TCP_URG_READ)
- return -EINVAL; /* Yes this is right ! */
- if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
- return -ENOTCONN;
- if (tp->urg_data & TCP_URG_VALID) {
- int err = 0;
- char c = tp->urg_data;
- if (!(flags & MSG_PEEK))
- tp->urg_data = TCP_URG_READ;
- /* Read urgent data. */
- msg->msg_flags |= MSG_OOB;
- if (len > 0) {
- if (!(flags & MSG_TRUNC))
- err = memcpy_toiovec(msg->msg_iov, &c, 1);
- len = 1;
- } else
- msg->msg_flags |= MSG_TRUNC;
- return err ? -EFAULT : len;
- }
- if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
- return 0;
- /* Fixed the recv(..., MSG_OOB) behaviour. BSD docs and
- * the available implementations agree in this case:
- * this call should never block, independent of the
- * blocking state of the socket.
- * Mike <pall@rz.uni-karlsruhe.de>
- */
- return -EAGAIN;
- }
- static int tcp_peek_sndq(struct sock *sk, struct msghdr *msg, int len)
- {
- struct sk_buff *skb;
- int copied = 0, err = 0;
- /* XXX -- need to support SO_PEEK_OFF */
- skb_queue_walk(&sk->sk_write_queue, skb) {
- err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, skb->len);
- if (err)
- break;
- copied += skb->len;
- }
- return err ?: copied;
- }
- /* Clean up the receive buffer for full frames taken by the user,
- * then send an ACK if necessary. COPIED is the number of bytes
- * tcp_recvmsg has given to the user so far, it speeds up the
- * calculation of whether or not we must ACK for the sake of
- * a window update.
- */
- void tcp_cleanup_rbuf(struct sock *sk, int copied)
- {
- struct tcp_sock *tp = tcp_sk(sk);
- bool time_to_ack = false;
- struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
- WARN(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq),
- "cleanup rbuf bug: copied %X seq %X rcvnxt %X\n",
- tp->copied_seq, TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt);
- if (inet_csk_ack_scheduled(sk)) {
- const struct inet_connection_sock *icsk = inet_csk(sk);
- /* Delayed ACKs frequently hit locked sockets during bulk
- * receive. */
- if (icsk->icsk_ack.blocked ||
- /* Once-per-two-segments ACK was not sent by tcp_input.c */
- tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
- /*
- * If this read emptied read buffer, we send ACK, if
- * connection is not bidirectional, user drained
- * receive buffer and there was a small segment
- * in queue.
- */
- (copied > 0 &&
- ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
- ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
- !icsk->icsk_ack.pingpong)) &&
- !atomic_read(&sk->sk_rmem_alloc)))
- time_to_ack = true;
- }
- /* We send an ACK if we can now advertise a non-zero window
- * which has been raised "significantly".
- *
- * Even if window raised up to infinity, do not send window open ACK
- * in states, where we will not receive more. It is useless.
- */
- if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
- __u32 rcv_window_now = tcp_receive_window(tp);
- /* Optimize, __tcp_select_window() is not cheap. */
- if (2*rcv_window_now <= tp->window_clamp) {
- __u32 new_window = __tcp_select_window(sk);
- /* Send ACK now, if this read freed lots of space
- * in our buffer. Certainly, new_window is new window.
- * We can advertise it now, if it is not less than current one.
- * "Lots" means "at least twice" here.
- */
- if (new_window && new_window >= 2 * rcv_window_now)
- time_to_ack = true;
- }
- }
- if (time_to_ack)
- tcp_send_ack(sk);
- }
- static void tcp_prequeue_process(struct sock *sk)
- {
- struct sk_buff *skb;
- struct tcp_sock *tp = tcp_sk(sk);
- NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPPREQUEUED);
- /* RX process wants to run with disabled BHs, though it is not
- * necessary */
- local_bh_disable();
- while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
- sk_backlog_rcv(sk, skb);
- local_bh_enable();
- /* Clear memory counter. */
- tp->ucopy.memory = 0;
- }
- #ifdef CONFIG_NET_DMA
- static void tcp_service_net_dma(struct sock *sk, bool wait)
- {
- dma_cookie_t done, used;
- dma_cookie_t last_issued;
- struct tcp_sock *tp = tcp_sk(sk);
- if (!tp->ucopy.dma_chan)
- return;
- last_issued = tp->ucopy.dma_cookie;
- dma_async_issue_pending(tp->ucopy.dma_chan);
- do {
- if (dma_async_is_tx_complete(tp->ucopy.dma_chan,
- last_issued, &done,
- &used) == DMA_SUCCESS) {
- /* Safe to free early-copied skbs now */
- __skb_queue_purge(&sk->sk_async_wait_queue);
- break;
- } else {
- struct sk_buff *skb;
- while ((skb = skb_peek(&sk->sk_async_wait_queue)) &&
- (dma_async_is_complete(skb->dma_cookie, done,
- used) == DMA_SUCCESS)) {
- __skb_dequeue(&sk->sk_async_wait_queue);
- kfree_skb(skb);
- }
- }
- } while (wait);
- }
- #endif
- static struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
- {
- struct sk_buff *skb;
- u32 offset;
- while ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) {
- offset = seq - TCP_SKB_CB(skb)->seq;
- if (tcp_hdr(skb)->syn)
- offset--;
- if (offset < skb->len || tcp_hdr(skb)->fin) {
- *off = offset;
- return skb;
- }
- /* This looks weird, but this can happen if TCP collapsing
- * splitted a fat GRO packet, while we released socket lock
- * in skb_splice_bits()
- */
- sk_eat_skb(sk, skb, false);
- }
- return NULL;
- }
- /*
- * This routine provides an alternative to tcp_recvmsg() for routines
- * that would like to handle copying from skbuffs directly in 'sendfile'
- * fashion.
- * Note:
- * - It is assumed that the socket was locked by the caller.
- * - The routine does not block.
- * - At present, there is no support for reading OOB data
- * or for 'peeking' the socket using this routine
- * (although both would be easy to implement).
- */
- int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
- sk_read_actor_t recv_actor)
- {
- struct sk_buff *skb;
- struct tcp_sock *tp = tcp_sk(sk);
- u32 seq = tp->copied_seq;
- u32 offset;
- int copied = 0;
- if (sk->sk_state == TCP_LISTEN)
- return -ENOTCONN;
- while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
- if (offset < skb->len) {
- int used;
- size_t len;
- len = skb->len - offset;
- /* Stop reading if we hit a patch of urgent data */
- if (tp->urg_data) {
- u32 urg_offset = tp->urg_seq - seq;
- if (urg_offset < len)
- len = urg_offset;
- if (!len)
- break;
- }
- used = recv_actor(desc, skb, offset, len);
- if (used <= 0) {
- if (!copied)
- copied = used;
- break;
- } else if (used <= len) {
- seq += used;
- copied += used;
- offset += used;
- }
- /* If recv_actor drops the lock (e.g. TCP splice
- * receive) the skb pointer might be invalid when
- * getting here: tcp_collapse might have deleted it
- * while aggregating skbs from the socket queue.
- */
- skb = tcp_recv_skb(sk, seq - 1, &offset);
- if (!skb)
- break;
- /* TCP coalescing might have appended data to the skb.
- * Try to splice more frags
- */
- if (offset + 1 != skb->len)
- continue;
- }
- if (tcp_hdr(skb)->fin) {
- sk_eat_skb(sk, skb, false);
- ++seq;
- break;
- }
- sk_eat_skb(sk, skb, false);
- if (!desc->count)
- break;
- tp->copied_seq = seq;
- }
- tp->copied_seq = seq;
- tcp_rcv_space_adjust(sk);
- /* Clean up data we have read: This will do ACK frames. */
- if (copied > 0) {
- tcp_recv_skb(sk, seq, &offset);
- tcp_cleanup_rbuf(sk, copied);
- }
- return copied;
- }
- EXPORT_SYMBOL(tcp_read_sock);
- /*
- * This routine copies from a sock struct into the user buffer.
- *
- * Technical note: in 2.3 we work on _locked_ socket, so that
- * tricks with *seq access order and skb->users are not required.
- * Probably, code can be easily improved even more.
- */
- int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
- size_t len, int nonblock, int flags, int *addr_len)
- {
- struct tcp_sock *tp = tcp_sk(sk);
- int copied = 0;
- u32 peek_seq;
- u32 *seq;
- unsigned long used;
- int err;
- int target; /* Read at least this many bytes */
- long timeo;
- struct task_struct *user_recv = NULL;
- bool copied_early = false;
- struct sk_buff *skb;
- u32 urg_hole = 0;
- lock_sock(sk);
- err = -ENOTCONN;
- if (sk->sk_state == TCP_LISTEN)
- goto out;
- timeo = sock_rcvtimeo(sk, nonblock);
- /* Urgent data needs to be handled specially. */
- if (flags & MSG_OOB)
- goto recv_urg;
- if (unlikely(tp->repair)) {
- err = -EPERM;
- if (!(flags & MSG_PEEK))
- goto out;
- if (tp->repair_queue == TCP_SEND_QUEUE)
- goto recv_sndq;
- err = -EINVAL;
- if (tp->repair_queue == TCP_NO_QUEUE)
- goto out;
- /* 'common' recv queue MSG_PEEK-ing */
- }
- seq = &tp->copied_seq;
- if (flags & MSG_PEEK) {
- peek_seq = tp->copied_seq;
- seq = &peek_seq;
- }
- target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
- #ifdef CONFIG_NET_DMA
- tp->ucopy.dma_chan = NULL;
- preempt_disable();
- skb = skb_peek_tail(&sk->sk_receive_queue);
- {
- int available = 0;
- if (skb)
- available = TCP_SKB_CB(skb)->seq + skb->len - (*seq);
- if ((available < target) &&
- (len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) &&
- !sysctl_tcp_low_latency &&
- net_dma_find_channel()) {
- preempt_enable_no_resched();
- tp->ucopy.pinned_list =
- dma_pin_iovec_pages(msg->msg_iov, len);
- } else {
- preempt_enable_no_resched();
- }
- }
- #endif
- do {
- u32 offset;
- /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
- if (tp->urg_data && tp->urg_seq == *seq) {
- if (copied)
- break;
- if (signal_pending(current)) {
- copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
- break;
- }
- }
- /* Next get a buffer. */
- skb_queue_walk(&sk->sk_receive_queue, skb) {
- /* Now that we have two receive queues this
- * shouldn't happen.
- */
- if (WARN(before(*seq, TCP_SKB_CB(skb)->seq),
- "recvmsg bug: copied %X seq %X rcvnxt %X fl %X\n",
- *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt,
- flags))
- break;
- offset = *seq - TCP_SKB_CB(skb)->seq;
- if (tcp_hdr(skb)->syn)
- offset--;
- if (offset < skb->len)
- goto found_ok_skb;
- if (tcp_hdr(skb)->fin)
- goto found_fin_ok;
- WARN(!(flags & MSG_PEEK),
- "recvmsg bug 2: copied %X seq %X rcvnxt %X fl %X\n",
- *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt, flags);
- }
- /* Well, if we have backlog, try to process it now yet. */
- if (copied >= target && !sk->sk_backlog.tail)
- break;
- if (copied) {
- if (sk->sk_err ||
- sk->sk_state == TCP_CLOSE ||
- (sk->sk_shutdown & RCV_SHUTDOWN) ||
- !timeo ||
- signal_pending(current))
- break;
- } else {
- if (sock_flag(sk, SOCK_DONE))
- break;
- if (sk->sk_err) {
- copied = sock_error(sk);
- break;
- }
- if (sk->sk_shutdown & RCV_SHUTDOWN)
- break;
- if (sk->sk_state == TCP_CLOSE) {
- if (!sock_flag(sk, SOCK_DONE)) {
- /* This occurs when user tries to read
- * from never connected socket.
- */
- copied = -ENOTCONN;
- break;
- }
- break;
- }
- if (!timeo) {
- copied = -EAGAIN;
- break;
- }
- if (signal_pending(current)) {
- copied = sock_intr_errno(timeo);
- break;
- }
- }
- tcp_cleanup_rbuf(sk, copied);
- if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
- /* Install new reader */
- if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) {
- user_recv = current;
- tp->ucopy.task = user_recv;
- tp->ucopy.iov = msg->msg_iov;
- }
- tp->ucopy.len = len;
- WARN_ON(tp->copied_seq != tp->rcv_nxt &&
- !(flags & (MSG_PEEK | MSG_TRUNC)));
- /* Ugly... If prequeue is not empty, we have to
- * process it before releasing socket, otherwise
- * order will be broken at second iteration.
- * More elegant solution is required!!!
- *
- * Look: we have the following (pseudo)queues:
- *
- * 1. packets in flight
- * 2. backlog
- * 3. prequeue
- * 4. receive_queue
- *
- * Each queue can be processed only if the next ones
- * are empty. At this point we have empty receive_queue.
- * But prequeue _can_ be not empty after 2nd iteration,
- * when we jumped to start of loop because backlog
- * processing added something to receive_queue.
- * We cannot release_sock(), because backlog contains
- * packets arrived _after_ prequeued ones.
- *
- * Shortly, algorithm is clear --- to process all
- * the queues in order. We could make it more directly,
- * requeueing packets from backlog to prequeue, if
- * is not empty. It is more elegant, but eats cycles,
- * unfortunately.
- */
- if (!skb_queue_empty(&tp->ucopy.prequeue))
- goto do_prequeue;
- /* __ Set realtime policy in scheduler __ */
- }
- #ifdef CONFIG_NET_DMA
- if (tp->ucopy.dma_chan) {
- if (tp->rcv_wnd == 0 &&
- !skb_queue_empty(&sk->sk_async_wait_queue)) {
- tcp_service_net_dma(sk, true);
- tcp_cleanup_rbuf(sk, copied);
- } else
- dma_async_issue_pending(tp->ucopy.dma_chan);
- }
- #endif
- if (copied >= target) {
- /* Do not sleep, just process backlog. */
- release_sock(sk);
- lock_sock(sk);
- } else
- sk_wait_data(sk, &timeo);
- #ifdef CONFIG_NET_DMA
- tcp_service_net_dma(sk, false); /* Don't block */
- tp->ucopy.wakeup = 0;
- #endif
- if (user_recv) {
- int chunk;
- /* __ Restore normal policy in scheduler __ */
- if ((chunk = len - tp->ucopy.len) != 0) {
- NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk);
- len -= chunk;
- copied += chunk;
- }
- if (tp->rcv_nxt == tp->copied_seq &&
- !skb_queue_empty(&tp->ucopy.prequeue)) {
- do_prequeue:
- tcp_prequeue_process(sk);
- if ((chunk = len - tp->ucopy.len) != 0) {
- NET_ADD_STATS_USER(sock_net(sk), LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
- len -= chunk;
- copied += chunk;
- }
- }
- }
- if ((flags & MSG_PEEK) &&
- (peek_seq - copied - urg_hole != tp->copied_seq)) {
- net_dbg_ratelimited("TCP(%s:%d): Application bug, race in MSG_PEEK\n",
- current->comm,
- task_pid_nr(current));
- peek_seq = tp->copied_seq;
- }
- continue;
- found_ok_skb:
- /* Ok so how much can we use? */
- used = skb->len - offset;
- if (len < used)
- used = len;
- /* Do we have urgent data here? */
- if (tp->urg_data) {
- u32 urg_offset = tp->urg_seq - *seq;
- if (urg_offset < used) {
- if (!urg_offset) {
- if (!sock_flag(sk, SOCK_URGINLINE)) {
- ++*seq;
- urg_hole++;
- offset++;
- used--;
- if (!used)
- goto skip_copy;
- }
- } else
- used = urg_offset;
- }
- }
- if (!(flags & MSG_TRUNC)) {
- #ifdef CONFIG_NET_DMA
- if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
- tp->ucopy.dma_chan = net_dma_find_channel();
- if (tp->ucopy.dma_chan) {
- tp->ucopy.dma_cookie = dma_skb_copy_datagram_iovec(
- tp->ucopy.dma_chan, skb, offset,
- msg->msg_iov, used,
- tp->ucopy.pinned_list);
- if (tp->ucopy.dma_cookie < 0) {
- pr_alert("%s: dma_cookie < 0\n",
- __func__);
- /* Exception. Bailout! */
- if (!copied)
- copied = -EFAULT;
- break;
- }
- dma_async_issue_pending(tp->ucopy.dma_chan…
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