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 _debug("send Rx idle ACK");
87 __rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, sp->hdr.serial,
88 true);
89 }
90
91 spin_unlock_bh(&call->lock);
92 }
93
94 /*
95 * destroy a packet that has an RxRPC control buffer
96 * - advance the hard-ACK state of the parent call (done here in case something
97 * in the kernel bypasses recvmsg() and steals the packet directly off of the
98 * socket receive queue)
99 */
100 void rxrpc_packet_destructor(struct sk_buff *skb)
101 {
102 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
103 struct rxrpc_call *call = sp->call;
104
105 _enter("%p{%p}", skb, call);
106
107 if (call) {
108 /* send the final ACK on a client call */
109 if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA)
110 rxrpc_hard_ACK_data(call, sp);
111 rxrpc_put_call(call);
112 sp->call = NULL;
113 }
114
115 if (skb->sk)
116 sock_rfree(skb);
117 _leave("");
118 }
119
120 /**
121 * rxrpc_kernel_free_skb - Free an RxRPC socket buffer
122 * @skb: The socket buffer to be freed
123 *
124 * Let RxRPC free its own socket buffer, permitting it to maintain debug
125 * accounting.
126 */
127 void rxrpc_kernel_free_skb(struct sk_buff *skb)
128 {
129 rxrpc_free_skb(skb);
130 }
131
132 EXPORT_SYMBOL(rxrpc_kernel_free_skb);
133
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