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