1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Management of Tx window, Tx resend, ACKs and out-of-sequence reception
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10 #include <linux/module.h>
11 #include <linux/circ_buf.h>
12 #include <linux/net.h>
13 #include <linux/skbuff.h>
14 #include <linux/slab.h>
15 #include <linux/udp.h>
17 #include <net/af_rxrpc.h>
18 #include "ar-internal.h"
21 * Propose a PING ACK be sent.
23 static void rxrpc_propose_ping(struct rxrpc_call
*call
,
24 bool immediate
, bool background
)
28 !test_and_set_bit(RXRPC_CALL_EV_PING
, &call
->events
))
29 rxrpc_queue_call(call
);
31 unsigned long now
= jiffies
;
32 unsigned long ping_at
= now
+ rxrpc_idle_ack_delay
;
34 if (time_before(ping_at
, call
->ping_at
)) {
35 WRITE_ONCE(call
->ping_at
, ping_at
);
36 rxrpc_reduce_call_timer(call
, ping_at
, now
,
37 rxrpc_timer_set_for_ping
);
43 * propose an ACK be sent
45 static void __rxrpc_propose_ACK(struct rxrpc_call
*call
, u8 ack_reason
,
46 u16 skew
, u32 serial
, bool immediate
,
48 enum rxrpc_propose_ack_trace why
)
50 enum rxrpc_propose_ack_outcome outcome
= rxrpc_propose_ack_use
;
51 unsigned long expiry
= rxrpc_soft_ack_delay
;
52 s8 prior
= rxrpc_ack_priority
[ack_reason
];
54 /* Pings are handled specially because we don't want to accidentally
55 * lose a ping response by subsuming it into a ping.
57 if (ack_reason
== RXRPC_ACK_PING
) {
58 rxrpc_propose_ping(call
, immediate
, background
);
62 /* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
63 * numbers, but we don't alter the timeout.
65 _debug("prior %u %u vs %u %u",
67 call
->ackr_reason
, rxrpc_ack_priority
[call
->ackr_reason
]);
68 if (ack_reason
== call
->ackr_reason
) {
69 if (RXRPC_ACK_UPDATEABLE
& (1 << ack_reason
)) {
70 outcome
= rxrpc_propose_ack_update
;
71 call
->ackr_serial
= serial
;
72 call
->ackr_skew
= skew
;
76 } else if (prior
> rxrpc_ack_priority
[call
->ackr_reason
]) {
77 call
->ackr_reason
= ack_reason
;
78 call
->ackr_serial
= serial
;
79 call
->ackr_skew
= skew
;
81 outcome
= rxrpc_propose_ack_subsume
;
85 case RXRPC_ACK_REQUESTED
:
86 if (rxrpc_requested_ack_delay
< expiry
)
87 expiry
= rxrpc_requested_ack_delay
;
93 if (rxrpc_soft_ack_delay
< expiry
)
94 expiry
= rxrpc_soft_ack_delay
;
98 if (rxrpc_idle_ack_delay
< expiry
)
99 expiry
= rxrpc_idle_ack_delay
;
107 if (test_bit(RXRPC_CALL_EV_ACK
, &call
->events
)) {
108 _debug("already scheduled");
109 } else if (immediate
|| expiry
== 0) {
110 _debug("immediate ACK %lx", call
->events
);
111 if (!test_and_set_bit(RXRPC_CALL_EV_ACK
, &call
->events
) &&
113 rxrpc_queue_call(call
);
115 unsigned long now
= jiffies
, ack_at
;
117 if (call
->peer
->rtt_usage
> 0)
118 ack_at
= nsecs_to_jiffies(call
->peer
->rtt
);
122 ack_at
+= READ_ONCE(call
->tx_backoff
);
124 if (time_before(ack_at
, call
->ack_at
)) {
125 WRITE_ONCE(call
->ack_at
, ack_at
);
126 rxrpc_reduce_call_timer(call
, ack_at
, now
,
127 rxrpc_timer_set_for_ack
);
132 trace_rxrpc_propose_ack(call
, why
, ack_reason
, serial
, immediate
,
133 background
, outcome
);
137 * propose an ACK be sent, locking the call structure
139 void rxrpc_propose_ACK(struct rxrpc_call
*call
, u8 ack_reason
,
140 u16 skew
, u32 serial
, bool immediate
, bool background
,
141 enum rxrpc_propose_ack_trace why
)
143 spin_lock_bh(&call
->lock
);
144 __rxrpc_propose_ACK(call
, ack_reason
, skew
, serial
,
145 immediate
, background
, why
);
146 spin_unlock_bh(&call
->lock
);
150 * Handle congestion being detected by the retransmit timeout.
152 static void rxrpc_congestion_timeout(struct rxrpc_call
*call
)
154 set_bit(RXRPC_CALL_RETRANS_TIMEOUT
, &call
->flags
);
158 * Perform retransmission of NAK'd and unack'd packets.
160 static void rxrpc_resend(struct rxrpc_call
*call
, unsigned long now_j
)
163 unsigned long resend_at
;
164 rxrpc_seq_t cursor
, seq
, top
;
165 ktime_t now
, max_age
, oldest
, ack_ts
, timeout
, min_timeo
;
167 u8 annotation
, anno_type
, retrans
= 0, unacked
= 0;
169 _enter("{%d,%d}", call
->tx_hard_ack
, call
->tx_top
);
171 if (call
->peer
->rtt_usage
> 1)
172 timeout
= ns_to_ktime(call
->peer
->rtt
* 3 / 2);
174 timeout
= ms_to_ktime(rxrpc_resend_timeout
);
175 min_timeo
= ns_to_ktime((1000000000 / HZ
) * 4);
176 if (ktime_before(timeout
, min_timeo
))
179 now
= ktime_get_real();
180 max_age
= ktime_sub(now
, timeout
);
182 spin_lock_bh(&call
->lock
);
184 cursor
= call
->tx_hard_ack
;
186 ASSERT(before_eq(cursor
, top
));
190 /* Scan the packet list without dropping the lock and decide which of
191 * the packets in the Tx buffer we're going to resend and what the new
192 * resend timeout will be.
194 trace_rxrpc_resend(call
, (cursor
+ 1) & RXRPC_RXTX_BUFF_MASK
);
196 for (seq
= cursor
+ 1; before_eq(seq
, top
); seq
++) {
197 ix
= seq
& RXRPC_RXTX_BUFF_MASK
;
198 annotation
= call
->rxtx_annotations
[ix
];
199 anno_type
= annotation
& RXRPC_TX_ANNO_MASK
;
200 annotation
&= ~RXRPC_TX_ANNO_MASK
;
201 if (anno_type
== RXRPC_TX_ANNO_ACK
)
204 skb
= call
->rxtx_buffer
[ix
];
205 rxrpc_see_skb(skb
, rxrpc_skb_tx_seen
);
207 if (anno_type
== RXRPC_TX_ANNO_UNACK
) {
208 if (ktime_after(skb
->tstamp
, max_age
)) {
209 if (ktime_before(skb
->tstamp
, oldest
))
210 oldest
= skb
->tstamp
;
213 if (!(annotation
& RXRPC_TX_ANNO_RESENT
))
217 /* Okay, we need to retransmit a packet. */
218 call
->rxtx_annotations
[ix
] = RXRPC_TX_ANNO_RETRANS
| annotation
;
220 trace_rxrpc_retransmit(call
, seq
, annotation
| anno_type
,
221 ktime_to_ns(ktime_sub(skb
->tstamp
, max_age
)));
224 resend_at
= nsecs_to_jiffies(ktime_to_ns(ktime_sub(now
, oldest
)));
225 resend_at
+= jiffies
+ rxrpc_resend_timeout
;
226 WRITE_ONCE(call
->resend_at
, resend_at
);
229 rxrpc_congestion_timeout(call
);
231 /* If there was nothing that needed retransmission then it's likely
232 * that an ACK got lost somewhere. Send a ping to find out instead of
233 * retransmitting data.
236 rxrpc_reduce_call_timer(call
, resend_at
, now_j
,
237 rxrpc_timer_set_for_resend
);
238 spin_unlock_bh(&call
->lock
);
239 ack_ts
= ktime_sub(now
, call
->acks_latest_ts
);
240 if (ktime_to_ns(ack_ts
) < call
->peer
->rtt
)
242 rxrpc_propose_ACK(call
, RXRPC_ACK_PING
, 0, 0, true, false,
243 rxrpc_propose_ack_ping_for_lost_ack
);
244 rxrpc_send_ack_packet(call
, true, NULL
);
248 /* Now go through the Tx window and perform the retransmissions. We
249 * have to drop the lock for each send. If an ACK comes in whilst the
250 * lock is dropped, it may clear some of the retransmission markers for
251 * packets that it soft-ACKs.
253 for (seq
= cursor
+ 1; before_eq(seq
, top
); seq
++) {
254 ix
= seq
& RXRPC_RXTX_BUFF_MASK
;
255 annotation
= call
->rxtx_annotations
[ix
];
256 anno_type
= annotation
& RXRPC_TX_ANNO_MASK
;
257 if (anno_type
!= RXRPC_TX_ANNO_RETRANS
)
260 skb
= call
->rxtx_buffer
[ix
];
261 rxrpc_get_skb(skb
, rxrpc_skb_tx_got
);
262 spin_unlock_bh(&call
->lock
);
264 if (rxrpc_send_data_packet(call
, skb
, true) < 0) {
265 rxrpc_free_skb(skb
, rxrpc_skb_tx_freed
);
269 if (rxrpc_is_client_call(call
))
270 rxrpc_expose_client_call(call
);
272 rxrpc_free_skb(skb
, rxrpc_skb_tx_freed
);
273 spin_lock_bh(&call
->lock
);
275 /* We need to clear the retransmit state, but there are two
276 * things we need to be aware of: A new ACK/NAK might have been
277 * received and the packet might have been hard-ACK'd (in which
278 * case it will no longer be in the buffer).
280 if (after(seq
, call
->tx_hard_ack
)) {
281 annotation
= call
->rxtx_annotations
[ix
];
282 anno_type
= annotation
& RXRPC_TX_ANNO_MASK
;
283 if (anno_type
== RXRPC_TX_ANNO_RETRANS
||
284 anno_type
== RXRPC_TX_ANNO_NAK
) {
285 annotation
&= ~RXRPC_TX_ANNO_MASK
;
286 annotation
|= RXRPC_TX_ANNO_UNACK
;
288 annotation
|= RXRPC_TX_ANNO_RESENT
;
289 call
->rxtx_annotations
[ix
] = annotation
;
292 if (after(call
->tx_hard_ack
, seq
))
293 seq
= call
->tx_hard_ack
;
297 spin_unlock_bh(&call
->lock
);
303 * Handle retransmission and deferred ACK/abort generation.
305 void rxrpc_process_call(struct work_struct
*work
)
307 struct rxrpc_call
*call
=
308 container_of(work
, struct rxrpc_call
, processor
);
309 rxrpc_serial_t
*send_ack
;
310 unsigned long now
, next
, t
;
311 unsigned int iterations
= 0;
313 rxrpc_see_call(call
);
315 //printk("\n--------------------\n");
316 _enter("{%d,%s,%lx}",
317 call
->debug_id
, rxrpc_call_states
[call
->state
], call
->events
);
320 /* Limit the number of times we do this before returning to the manager */
325 if (test_and_clear_bit(RXRPC_CALL_EV_ABORT
, &call
->events
)) {
326 rxrpc_send_abort_packet(call
);
330 if (call
->state
== RXRPC_CALL_COMPLETE
) {
331 del_timer_sync(&call
->timer
);
332 rxrpc_notify_socket(call
);
336 /* Work out if any timeouts tripped */
338 t
= READ_ONCE(call
->expect_rx_by
);
339 if (time_after_eq(now
, t
)) {
340 trace_rxrpc_timer(call
, rxrpc_timer_exp_normal
, now
);
341 set_bit(RXRPC_CALL_EV_EXPIRED
, &call
->events
);
344 t
= READ_ONCE(call
->expect_req_by
);
345 if (call
->state
== RXRPC_CALL_SERVER_RECV_REQUEST
&&
346 time_after_eq(now
, t
)) {
347 trace_rxrpc_timer(call
, rxrpc_timer_exp_idle
, now
);
348 set_bit(RXRPC_CALL_EV_EXPIRED
, &call
->events
);
351 t
= READ_ONCE(call
->expect_term_by
);
352 if (time_after_eq(now
, t
)) {
353 trace_rxrpc_timer(call
, rxrpc_timer_exp_hard
, now
);
354 set_bit(RXRPC_CALL_EV_EXPIRED
, &call
->events
);
357 t
= READ_ONCE(call
->ack_at
);
358 if (time_after_eq(now
, t
)) {
359 trace_rxrpc_timer(call
, rxrpc_timer_exp_ack
, now
);
360 cmpxchg(&call
->ack_at
, t
, now
+ MAX_JIFFY_OFFSET
);
361 set_bit(RXRPC_CALL_EV_ACK
, &call
->events
);
364 t
= READ_ONCE(call
->ack_lost_at
);
365 if (time_after_eq(now
, t
)) {
366 trace_rxrpc_timer(call
, rxrpc_timer_exp_lost_ack
, now
);
367 cmpxchg(&call
->ack_lost_at
, t
, now
+ MAX_JIFFY_OFFSET
);
368 set_bit(RXRPC_CALL_EV_ACK_LOST
, &call
->events
);
371 t
= READ_ONCE(call
->keepalive_at
);
372 if (time_after_eq(now
, t
)) {
373 trace_rxrpc_timer(call
, rxrpc_timer_exp_keepalive
, now
);
374 cmpxchg(&call
->keepalive_at
, t
, now
+ MAX_JIFFY_OFFSET
);
375 rxrpc_propose_ACK(call
, RXRPC_ACK_PING
, 0, 0, true, true,
376 rxrpc_propose_ack_ping_for_keepalive
);
377 set_bit(RXRPC_CALL_EV_PING
, &call
->events
);
380 t
= READ_ONCE(call
->ping_at
);
381 if (time_after_eq(now
, t
)) {
382 trace_rxrpc_timer(call
, rxrpc_timer_exp_ping
, now
);
383 cmpxchg(&call
->ping_at
, t
, now
+ MAX_JIFFY_OFFSET
);
384 set_bit(RXRPC_CALL_EV_PING
, &call
->events
);
387 t
= READ_ONCE(call
->resend_at
);
388 if (time_after_eq(now
, t
)) {
389 trace_rxrpc_timer(call
, rxrpc_timer_exp_resend
, now
);
390 cmpxchg(&call
->resend_at
, t
, now
+ MAX_JIFFY_OFFSET
);
391 set_bit(RXRPC_CALL_EV_RESEND
, &call
->events
);
395 if (test_and_clear_bit(RXRPC_CALL_EV_EXPIRED
, &call
->events
)) {
396 if (test_bit(RXRPC_CALL_RX_HEARD
, &call
->flags
) &&
397 (int)call
->conn
->hi_serial
- (int)call
->rx_serial
> 0) {
398 trace_rxrpc_call_reset(call
);
399 rxrpc_abort_call("EXP", call
, 0, RX_USER_ABORT
, -ECONNRESET
);
401 rxrpc_abort_call("EXP", call
, 0, RX_USER_ABORT
, -ETIME
);
403 set_bit(RXRPC_CALL_EV_ABORT
, &call
->events
);
408 if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST
, &call
->events
)) {
409 call
->acks_lost_top
= call
->tx_top
;
410 rxrpc_propose_ACK(call
, RXRPC_ACK_PING
, 0, 0, true, false,
411 rxrpc_propose_ack_ping_for_lost_ack
);
412 send_ack
= &call
->acks_lost_ping
;
415 if (test_and_clear_bit(RXRPC_CALL_EV_ACK
, &call
->events
) ||
417 if (call
->ackr_reason
) {
418 rxrpc_send_ack_packet(call
, false, send_ack
);
423 if (test_and_clear_bit(RXRPC_CALL_EV_PING
, &call
->events
)) {
424 rxrpc_send_ack_packet(call
, true, NULL
);
428 if (test_and_clear_bit(RXRPC_CALL_EV_RESEND
, &call
->events
)) {
429 rxrpc_resend(call
, now
);
433 /* Make sure the timer is restarted */
434 next
= call
->expect_rx_by
;
436 #define set(T) { t = READ_ONCE(T); if (time_before(t, next)) next = t; }
438 set(call
->expect_req_by
);
439 set(call
->expect_term_by
);
441 set(call
->ack_lost_at
);
442 set(call
->resend_at
);
443 set(call
->keepalive_at
);
447 if (time_after_eq(now
, next
))
450 rxrpc_reduce_call_timer(call
, next
, now
, rxrpc_timer_restart
);
452 /* other events may have been raised since we started checking */
453 if (call
->events
&& call
->state
< RXRPC_CALL_COMPLETE
)
457 rxrpc_put_call(call
, rxrpc_call_put
);
463 __rxrpc_queue_call(call
);