net/rxrpc/skbuff.c

   1 /* ar-skbuff.c: socket buffer destruction handling
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/module.h>
  15 #include <linux/net.h>
  16 #include <linux/skbuff.h>
  17 #include <net/sock.h>
  18 #include <net/af_rxrpc.h>
  19 #include "ar-internal.h"
  20
  21 /*
  22  * set up for the ACK at the end of the receive phase when we discard the final
  23  * receive phase data packet
  24  * - called with softirqs disabled
  25  */
  26 static void rxrpc_request_final_ACK(struct rxrpc_call *call)
  27 {
  28         /* the call may be aborted before we have a chance to ACK it */
  29         write_lock(&call->state_lock);
  30
  31         switch (call->state) {
  32         case RXRPC_CALL_CLIENT_RECV_REPLY:
  33                 call->state = RXRPC_CALL_CLIENT_FINAL_ACK;
  34                 _debug("request final ACK");
  35
  36                 /* get an extra ref on the call for the final-ACK generator to
  37                  * release */
  38                 rxrpc_get_call(call);
  39                 set_bit(RXRPC_CALL_EV_ACK_FINAL, &call->events);
  40                 if (try_to_del_timer_sync(&call->ack_timer) >= 0)
  41                         rxrpc_queue_call(call);
  42                 break;
  43
  44         case RXRPC_CALL_SERVER_RECV_REQUEST:
  45                 call->state = RXRPC_CALL_SERVER_ACK_REQUEST;
  46         default:
  47                 break;
  48         }
  49
  50         write_unlock(&call->state_lock);
  51 }
  52
  53 /*
  54  * drop the bottom ACK off of the call ACK window and advance the window
  55  */
  56 static void rxrpc_hard_ACK_data(struct rxrpc_call *call,
  57                                 struct rxrpc_skb_priv *sp)
  58 {
  59         int loop;
  60         u32 seq;
  61
  62         spin_lock_bh(&call->lock);
  63
  64         _debug("hard ACK #%u", sp->hdr.seq);
  65
  66         for (loop = 0; loop < RXRPC_ACKR_WINDOW_ASZ; loop++) {
  67                 call->ackr_window[loop] >>= 1;
  68                 call->ackr_window[loop] |=
  69                         call->ackr_window[loop + 1] << (BITS_PER_LONG - 1);
  70         }
  71
  72         seq = sp->hdr.seq;
  73         ASSERTCMP(seq, ==, call->rx_data_eaten + 1);
  74         call->rx_data_eaten = seq;
  75
  76         if (call->ackr_win_top < UINT_MAX)
  77                 call->ackr_win_top++;
  78
  79         ASSERTIFCMP(call->state <= RXRPC_CALL_COMPLETE,
  80                     call->rx_data_post, >=, call->rx_data_recv);
  81         ASSERTIFCMP(call->state <= RXRPC_CALL_COMPLETE,
  82                     call->rx_data_recv, >=, call->rx_data_eaten);
  83
  84         if (sp->hdr.flags & RXRPC_LAST_PACKET) {
  85                 rxrpc_request_final_ACK(call);
  86         } else if (atomic_dec_and_test(&call->ackr_not_idle) &&
  87                    test_and_clear_bit(RXRPC_CALL_TX_SOFT_ACK, &call->flags)) {
  88                 /* We previously soft-ACK'd some received packets that have now
  89                  * been consumed, so send a hard-ACK if no more packets are
  90                  * immediately forthcoming to allow the transmitter to free up
  91                  * its Tx bufferage.
  92                  */
  93                 _debug("send Rx idle ACK");
  94                 __rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, sp->hdr.serial,
  95                                     false);
  96         }
  97
  98         spin_unlock_bh(&call->lock);
  99 }
 100
 101 /*
 102  * destroy a packet that has an RxRPC control buffer
 103  * - advance the hard-ACK state of the parent call (done here in case something
 104  *   in the kernel bypasses recvmsg() and steals the packet directly off of the
 105  *   socket receive queue)
 106  */
 107 void rxrpc_packet_destructor(struct sk_buff *skb)
 108 {
 109         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 110         struct rxrpc_call *call = sp->call;
 111
 112         _enter("%p{%p}", skb, call);
 113
 114         if (call) {
 115                 /* send the final ACK on a client call */
 116                 if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA)
 117                         rxrpc_hard_ACK_data(call, sp);
 118                 rxrpc_put_call(call);
 119                 sp->call = NULL;
 120         }
 121
 122         if (skb->sk)
 123                 sock_rfree(skb);
 124         _leave("");
 125 }
 126
 127 /**
 128  * rxrpc_kernel_free_skb - Free an RxRPC socket buffer
 129  * @skb: The socket buffer to be freed
 130  *
 131  * Let RxRPC free its own socket buffer, permitting it to maintain debug
 132  * accounting.
 133  */
 134 void rxrpc_kernel_free_skb(struct sk_buff *skb)
 135 {
 136         rxrpc_free_skb(skb);
 137 }
 138 EXPORT_SYMBOL(rxrpc_kernel_free_skb);