1 /* Management of Tx window, Tx resend, ACKs and out-of-sequence reception
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14 #include <linux/module.h>
15 #include <linux/circ_buf.h>
16 #include <linux/net.h>
17 #include <linux/skbuff.h>
18 #include <linux/slab.h>
19 #include <linux/udp.h>
21 #include <net/af_rxrpc.h>
22 #include "ar-internal.h"
27 void rxrpc_set_timer(struct rxrpc_call
*call
, enum rxrpc_timer_trace why
,
30 unsigned long t_j
, now_j
= jiffies
;
34 read_lock_bh(&call
->state_lock
);
36 if (call
->state
< RXRPC_CALL_COMPLETE
) {
38 if (!ktime_after(t
, now
))
41 if (!ktime_after(call
->resend_at
, now
)) {
42 call
->resend_at
= call
->expire_at
;
43 if (!test_and_set_bit(RXRPC_CALL_EV_RESEND
, &call
->events
))
45 } else if (ktime_before(call
->resend_at
, t
)) {
49 if (!ktime_after(call
->ack_at
, now
)) {
50 call
->ack_at
= call
->expire_at
;
51 if (!test_and_set_bit(RXRPC_CALL_EV_ACK
, &call
->events
))
53 } else if (ktime_before(call
->ack_at
, t
)) {
57 t_j
= nsecs_to_jiffies(ktime_to_ns(ktime_sub(t
, now
)));
60 /* We have to make sure that the calculated jiffies value falls
61 * at or after the nsec value, or we may loop ceaselessly
62 * because the timer times out, but we haven't reached the nsec
67 if (call
->timer
.expires
!= t_j
|| !timer_pending(&call
->timer
)) {
68 mod_timer(&call
->timer
, t_j
);
69 trace_rxrpc_timer(call
, why
, now
, now_j
);
73 rxrpc_queue_call(call
);
77 read_unlock_bh(&call
->state_lock
);
81 * propose an ACK be sent
83 static void __rxrpc_propose_ACK(struct rxrpc_call
*call
, u8 ack_reason
,
84 u16 skew
, u32 serial
, bool immediate
,
86 enum rxrpc_propose_ack_trace why
)
88 enum rxrpc_propose_ack_outcome outcome
= rxrpc_propose_ack_use
;
89 unsigned int expiry
= rxrpc_soft_ack_delay
;
91 s8 prior
= rxrpc_ack_priority
[ack_reason
];
93 /* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
94 * numbers, but we don't alter the timeout.
96 _debug("prior %u %u vs %u %u",
98 call
->ackr_reason
, rxrpc_ack_priority
[call
->ackr_reason
]);
99 if (ack_reason
== call
->ackr_reason
) {
100 if (RXRPC_ACK_UPDATEABLE
& (1 << ack_reason
)) {
101 outcome
= rxrpc_propose_ack_update
;
102 call
->ackr_serial
= serial
;
103 call
->ackr_skew
= skew
;
107 } else if (prior
> rxrpc_ack_priority
[call
->ackr_reason
]) {
108 call
->ackr_reason
= ack_reason
;
109 call
->ackr_serial
= serial
;
110 call
->ackr_skew
= skew
;
112 outcome
= rxrpc_propose_ack_subsume
;
115 switch (ack_reason
) {
116 case RXRPC_ACK_REQUESTED
:
117 if (rxrpc_requested_ack_delay
< expiry
)
118 expiry
= rxrpc_requested_ack_delay
;
123 case RXRPC_ACK_DELAY
:
124 if (rxrpc_soft_ack_delay
< expiry
)
125 expiry
= rxrpc_soft_ack_delay
;
130 if (rxrpc_idle_ack_delay
< expiry
)
131 expiry
= rxrpc_idle_ack_delay
;
139 if (test_bit(RXRPC_CALL_EV_ACK
, &call
->events
)) {
140 _debug("already scheduled");
141 } else if (immediate
|| expiry
== 0) {
142 _debug("immediate ACK %lx", call
->events
);
143 if (!test_and_set_bit(RXRPC_CALL_EV_ACK
, &call
->events
) &&
145 rxrpc_queue_call(call
);
147 now
= ktime_get_real();
148 ack_at
= ktime_add_ms(now
, expiry
);
149 if (ktime_before(ack_at
, call
->ack_at
)) {
150 call
->ack_at
= ack_at
;
151 rxrpc_set_timer(call
, rxrpc_timer_set_for_ack
, now
);
156 trace_rxrpc_propose_ack(call
, why
, ack_reason
, serial
, immediate
,
157 background
, outcome
);
161 * propose an ACK be sent, locking the call structure
163 void rxrpc_propose_ACK(struct rxrpc_call
*call
, u8 ack_reason
,
164 u16 skew
, u32 serial
, bool immediate
, bool background
,
165 enum rxrpc_propose_ack_trace why
)
167 spin_lock_bh(&call
->lock
);
168 __rxrpc_propose_ACK(call
, ack_reason
, skew
, serial
,
169 immediate
, background
, why
);
170 spin_unlock_bh(&call
->lock
);
174 * Handle congestion being detected by the retransmit timeout.
176 static void rxrpc_congestion_timeout(struct rxrpc_call
*call
)
178 set_bit(RXRPC_CALL_RETRANS_TIMEOUT
, &call
->flags
);
182 * Perform retransmission of NAK'd and unack'd packets.
184 static void rxrpc_resend(struct rxrpc_call
*call
, ktime_t now
)
186 struct rxrpc_skb_priv
*sp
;
188 rxrpc_seq_t cursor
, seq
, top
;
189 ktime_t max_age
, oldest
, ack_ts
;
191 u8 annotation
, anno_type
, retrans
= 0, unacked
= 0;
193 _enter("{%d,%d}", call
->tx_hard_ack
, call
->tx_top
);
195 max_age
= ktime_sub_ms(now
, rxrpc_resend_timeout
);
197 spin_lock_bh(&call
->lock
);
199 cursor
= call
->tx_hard_ack
;
201 ASSERT(before_eq(cursor
, top
));
205 /* Scan the packet list without dropping the lock and decide which of
206 * the packets in the Tx buffer we're going to resend and what the new
207 * resend timeout will be.
210 for (seq
= cursor
+ 1; before_eq(seq
, top
); seq
++) {
211 ix
= seq
& RXRPC_RXTX_BUFF_MASK
;
212 annotation
= call
->rxtx_annotations
[ix
];
213 anno_type
= annotation
& RXRPC_TX_ANNO_MASK
;
214 annotation
&= ~RXRPC_TX_ANNO_MASK
;
215 if (anno_type
== RXRPC_TX_ANNO_ACK
)
218 skb
= call
->rxtx_buffer
[ix
];
219 rxrpc_see_skb(skb
, rxrpc_skb_tx_seen
);
222 if (anno_type
== RXRPC_TX_ANNO_UNACK
) {
223 if (ktime_after(skb
->tstamp
, max_age
)) {
224 if (ktime_before(skb
->tstamp
, oldest
))
225 oldest
= skb
->tstamp
;
228 if (!(annotation
& RXRPC_TX_ANNO_RESENT
))
232 /* Okay, we need to retransmit a packet. */
233 call
->rxtx_annotations
[ix
] = RXRPC_TX_ANNO_RETRANS
| annotation
;
235 trace_rxrpc_retransmit(call
, seq
, annotation
| anno_type
,
236 ktime_to_ns(ktime_sub(skb
->tstamp
, max_age
)));
239 call
->resend_at
= ktime_add_ms(oldest
, rxrpc_resend_timeout
);
242 rxrpc_congestion_timeout(call
);
244 /* If there was nothing that needed retransmission then it's likely
245 * that an ACK got lost somewhere. Send a ping to find out instead of
246 * retransmitting data.
249 rxrpc_set_timer(call
, rxrpc_timer_set_for_resend
, now
);
250 spin_unlock_bh(&call
->lock
);
251 ack_ts
= ktime_sub(now
, call
->acks_latest_ts
);
252 if (ktime_to_ns(ack_ts
) < call
->peer
->rtt
)
254 rxrpc_propose_ACK(call
, RXRPC_ACK_PING
, 0, 0, true, false,
255 rxrpc_propose_ack_ping_for_lost_ack
);
256 rxrpc_send_call_packet(call
, RXRPC_PACKET_TYPE_ACK
);
260 /* Now go through the Tx window and perform the retransmissions. We
261 * have to drop the lock for each send. If an ACK comes in whilst the
262 * lock is dropped, it may clear some of the retransmission markers for
263 * packets that it soft-ACKs.
265 for (seq
= cursor
+ 1; before_eq(seq
, top
); seq
++) {
266 ix
= seq
& RXRPC_RXTX_BUFF_MASK
;
267 annotation
= call
->rxtx_annotations
[ix
];
268 anno_type
= annotation
& RXRPC_TX_ANNO_MASK
;
269 if (anno_type
!= RXRPC_TX_ANNO_RETRANS
)
272 skb
= call
->rxtx_buffer
[ix
];
273 rxrpc_get_skb(skb
, rxrpc_skb_tx_got
);
274 spin_unlock_bh(&call
->lock
);
276 if (rxrpc_send_data_packet(call
, skb
, true) < 0) {
277 rxrpc_free_skb(skb
, rxrpc_skb_tx_freed
);
281 if (rxrpc_is_client_call(call
))
282 rxrpc_expose_client_call(call
);
284 rxrpc_free_skb(skb
, rxrpc_skb_tx_freed
);
285 spin_lock_bh(&call
->lock
);
287 /* We need to clear the retransmit state, but there are two
288 * things we need to be aware of: A new ACK/NAK might have been
289 * received and the packet might have been hard-ACK'd (in which
290 * case it will no longer be in the buffer).
292 if (after(seq
, call
->tx_hard_ack
)) {
293 annotation
= call
->rxtx_annotations
[ix
];
294 anno_type
= annotation
& RXRPC_TX_ANNO_MASK
;
295 if (anno_type
== RXRPC_TX_ANNO_RETRANS
||
296 anno_type
== RXRPC_TX_ANNO_NAK
) {
297 annotation
&= ~RXRPC_TX_ANNO_MASK
;
298 annotation
|= RXRPC_TX_ANNO_UNACK
;
300 annotation
|= RXRPC_TX_ANNO_RESENT
;
301 call
->rxtx_annotations
[ix
] = annotation
;
304 if (after(call
->tx_hard_ack
, seq
))
305 seq
= call
->tx_hard_ack
;
309 spin_unlock_bh(&call
->lock
);
315 * Handle retransmission and deferred ACK/abort generation.
317 void rxrpc_process_call(struct work_struct
*work
)
319 struct rxrpc_call
*call
=
320 container_of(work
, struct rxrpc_call
, processor
);
323 rxrpc_see_call(call
);
325 //printk("\n--------------------\n");
326 _enter("{%d,%s,%lx}",
327 call
->debug_id
, rxrpc_call_states
[call
->state
], call
->events
);
330 if (test_and_clear_bit(RXRPC_CALL_EV_ABORT
, &call
->events
)) {
331 rxrpc_send_call_packet(call
, RXRPC_PACKET_TYPE_ABORT
);
335 if (call
->state
== RXRPC_CALL_COMPLETE
) {
336 del_timer_sync(&call
->timer
);
340 now
= ktime_get_real();
341 if (ktime_before(call
->expire_at
, now
)) {
342 rxrpc_abort_call("EXP", call
, 0, RX_CALL_TIMEOUT
, ETIME
);
343 set_bit(RXRPC_CALL_EV_ABORT
, &call
->events
);
347 if (test_and_clear_bit(RXRPC_CALL_EV_ACK
, &call
->events
)) {
348 call
->ack_at
= call
->expire_at
;
349 if (call
->ackr_reason
) {
350 rxrpc_send_call_packet(call
, RXRPC_PACKET_TYPE_ACK
);
355 if (test_and_clear_bit(RXRPC_CALL_EV_RESEND
, &call
->events
)) {
356 rxrpc_resend(call
, now
);
360 rxrpc_set_timer(call
, rxrpc_timer_set_for_resend
, now
);
362 /* other events may have been raised since we started checking */
363 if (call
->events
&& call
->state
< RXRPC_CALL_COMPLETE
) {
364 __rxrpc_queue_call(call
);
369 rxrpc_put_call(call
, rxrpc_call_put
);