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); 139