Merge tag 'locking-urgent-2021-05-23' of git://git.kernel.org/pub/scm/linux/kernel...
[linux-2.6-microblaze.git] / net / rxrpc / call_event.c
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Management of Tx window, Tx resend, ACKs and out-of-sequence reception
3  *
4  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5  * Written by David Howells (dhowells@redhat.com)
6  */
7
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
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>
16 #include <net/sock.h>
17 #include <net/af_rxrpc.h>
18 #include "ar-internal.h"
19
20 /*
21  * Propose a PING ACK be sent.
22  */
23 static void rxrpc_propose_ping(struct rxrpc_call *call,
24                                bool immediate, bool background)
25 {
26         if (immediate) {
27                 if (background &&
28                     !test_and_set_bit(RXRPC_CALL_EV_PING, &call->events))
29                         rxrpc_queue_call(call);
30         } else {
31                 unsigned long now = jiffies;
32                 unsigned long ping_at = now + rxrpc_idle_ack_delay;
33
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);
38                 }
39         }
40 }
41
42 /*
43  * propose an ACK be sent
44  */
45 static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
46                                 u32 serial, bool immediate, bool background,
47                                 enum rxrpc_propose_ack_trace why)
48 {
49         enum rxrpc_propose_ack_outcome outcome = rxrpc_propose_ack_use;
50         unsigned long expiry = rxrpc_soft_ack_delay;
51         s8 prior = rxrpc_ack_priority[ack_reason];
52
53         /* Pings are handled specially because we don't want to accidentally
54          * lose a ping response by subsuming it into a ping.
55          */
56         if (ack_reason == RXRPC_ACK_PING) {
57                 rxrpc_propose_ping(call, immediate, background);
58                 goto trace;
59         }
60
61         /* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
62          * numbers, but we don't alter the timeout.
63          */
64         _debug("prior %u %u vs %u %u",
65                ack_reason, prior,
66                call->ackr_reason, rxrpc_ack_priority[call->ackr_reason]);
67         if (ack_reason == call->ackr_reason) {
68                 if (RXRPC_ACK_UPDATEABLE & (1 << ack_reason)) {
69                         outcome = rxrpc_propose_ack_update;
70                         call->ackr_serial = serial;
71                 }
72                 if (!immediate)
73                         goto trace;
74         } else if (prior > rxrpc_ack_priority[call->ackr_reason]) {
75                 call->ackr_reason = ack_reason;
76                 call->ackr_serial = serial;
77         } else {
78                 outcome = rxrpc_propose_ack_subsume;
79         }
80
81         switch (ack_reason) {
82         case RXRPC_ACK_REQUESTED:
83                 if (rxrpc_requested_ack_delay < expiry)
84                         expiry = rxrpc_requested_ack_delay;
85                 if (serial == 1)
86                         immediate = false;
87                 break;
88
89         case RXRPC_ACK_DELAY:
90                 if (rxrpc_soft_ack_delay < expiry)
91                         expiry = rxrpc_soft_ack_delay;
92                 break;
93
94         case RXRPC_ACK_IDLE:
95                 if (rxrpc_idle_ack_delay < expiry)
96                         expiry = rxrpc_idle_ack_delay;
97                 break;
98
99         default:
100                 immediate = true;
101                 break;
102         }
103
104         if (test_bit(RXRPC_CALL_EV_ACK, &call->events)) {
105                 _debug("already scheduled");
106         } else if (immediate || expiry == 0) {
107                 _debug("immediate ACK %lx", call->events);
108                 if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events) &&
109                     background)
110                         rxrpc_queue_call(call);
111         } else {
112                 unsigned long now = jiffies, ack_at;
113
114                 if (call->peer->srtt_us != 0)
115                         ack_at = usecs_to_jiffies(call->peer->srtt_us >> 3);
116                 else
117                         ack_at = expiry;
118
119                 ack_at += READ_ONCE(call->tx_backoff);
120                 ack_at += now;
121                 if (time_before(ack_at, call->ack_at)) {
122                         WRITE_ONCE(call->ack_at, ack_at);
123                         rxrpc_reduce_call_timer(call, ack_at, now,
124                                                 rxrpc_timer_set_for_ack);
125                 }
126         }
127
128 trace:
129         trace_rxrpc_propose_ack(call, why, ack_reason, serial, immediate,
130                                 background, outcome);
131 }
132
133 /*
134  * propose an ACK be sent, locking the call structure
135  */
136 void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
137                        u32 serial, bool immediate, bool background,
138                        enum rxrpc_propose_ack_trace why)
139 {
140         spin_lock_bh(&call->lock);
141         __rxrpc_propose_ACK(call, ack_reason, serial,
142                             immediate, background, why);
143         spin_unlock_bh(&call->lock);
144 }
145
146 /*
147  * Handle congestion being detected by the retransmit timeout.
148  */
149 static void rxrpc_congestion_timeout(struct rxrpc_call *call)
150 {
151         set_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags);
152 }
153
154 /*
155  * Perform retransmission of NAK'd and unack'd packets.
156  */
157 static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j)
158 {
159         struct sk_buff *skb;
160         unsigned long resend_at, rto_j;
161         rxrpc_seq_t cursor, seq, top;
162         ktime_t now, max_age, oldest, ack_ts;
163         int ix;
164         u8 annotation, anno_type, retrans = 0, unacked = 0;
165
166         _enter("{%d,%d}", call->tx_hard_ack, call->tx_top);
167
168         rto_j = call->peer->rto_j;
169
170         now = ktime_get_real();
171         max_age = ktime_sub(now, jiffies_to_usecs(rto_j));
172
173         spin_lock_bh(&call->lock);
174
175         cursor = call->tx_hard_ack;
176         top = call->tx_top;
177         ASSERT(before_eq(cursor, top));
178         if (cursor == top)
179                 goto out_unlock;
180
181         /* Scan the packet list without dropping the lock and decide which of
182          * the packets in the Tx buffer we're going to resend and what the new
183          * resend timeout will be.
184          */
185         trace_rxrpc_resend(call, (cursor + 1) & RXRPC_RXTX_BUFF_MASK);
186         oldest = now;
187         for (seq = cursor + 1; before_eq(seq, top); seq++) {
188                 ix = seq & RXRPC_RXTX_BUFF_MASK;
189                 annotation = call->rxtx_annotations[ix];
190                 anno_type = annotation & RXRPC_TX_ANNO_MASK;
191                 annotation &= ~RXRPC_TX_ANNO_MASK;
192                 if (anno_type == RXRPC_TX_ANNO_ACK)
193                         continue;
194
195                 skb = call->rxtx_buffer[ix];
196                 rxrpc_see_skb(skb, rxrpc_skb_seen);
197
198                 if (anno_type == RXRPC_TX_ANNO_UNACK) {
199                         if (ktime_after(skb->tstamp, max_age)) {
200                                 if (ktime_before(skb->tstamp, oldest))
201                                         oldest = skb->tstamp;
202                                 continue;
203                         }
204                         if (!(annotation & RXRPC_TX_ANNO_RESENT))
205                                 unacked++;
206                 }
207
208                 /* Okay, we need to retransmit a packet. */
209                 call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS | annotation;
210                 retrans++;
211                 trace_rxrpc_retransmit(call, seq, annotation | anno_type,
212                                        ktime_to_ns(ktime_sub(skb->tstamp, max_age)));
213         }
214
215         resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
216         resend_at += jiffies + rto_j;
217         WRITE_ONCE(call->resend_at, resend_at);
218
219         if (unacked)
220                 rxrpc_congestion_timeout(call);
221
222         /* If there was nothing that needed retransmission then it's likely
223          * that an ACK got lost somewhere.  Send a ping to find out instead of
224          * retransmitting data.
225          */
226         if (!retrans) {
227                 rxrpc_reduce_call_timer(call, resend_at, now_j,
228                                         rxrpc_timer_set_for_resend);
229                 spin_unlock_bh(&call->lock);
230                 ack_ts = ktime_sub(now, call->acks_latest_ts);
231                 if (ktime_to_us(ack_ts) < (call->peer->srtt_us >> 3))
232                         goto out;
233                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false,
234                                   rxrpc_propose_ack_ping_for_lost_ack);
235                 rxrpc_send_ack_packet(call, true, NULL);
236                 goto out;
237         }
238
239         /* Now go through the Tx window and perform the retransmissions.  We
240          * have to drop the lock for each send.  If an ACK comes in whilst the
241          * lock is dropped, it may clear some of the retransmission markers for
242          * packets that it soft-ACKs.
243          */
244         for (seq = cursor + 1; before_eq(seq, top); seq++) {
245                 ix = seq & RXRPC_RXTX_BUFF_MASK;
246                 annotation = call->rxtx_annotations[ix];
247                 anno_type = annotation & RXRPC_TX_ANNO_MASK;
248                 if (anno_type != RXRPC_TX_ANNO_RETRANS)
249                         continue;
250
251                 /* We need to reset the retransmission state, but we need to do
252                  * so before we drop the lock as a new ACK/NAK may come in and
253                  * confuse things
254                  */
255                 annotation &= ~RXRPC_TX_ANNO_MASK;
256                 annotation |= RXRPC_TX_ANNO_UNACK | RXRPC_TX_ANNO_RESENT;
257                 call->rxtx_annotations[ix] = annotation;
258
259                 skb = call->rxtx_buffer[ix];
260                 if (!skb)
261                         continue;
262
263                 rxrpc_get_skb(skb, rxrpc_skb_got);
264                 spin_unlock_bh(&call->lock);
265
266                 if (rxrpc_send_data_packet(call, skb, true) < 0) {
267                         rxrpc_free_skb(skb, rxrpc_skb_freed);
268                         return;
269                 }
270
271                 if (rxrpc_is_client_call(call))
272                         rxrpc_expose_client_call(call);
273
274                 rxrpc_free_skb(skb, rxrpc_skb_freed);
275                 spin_lock_bh(&call->lock);
276                 if (after(call->tx_hard_ack, seq))
277                         seq = call->tx_hard_ack;
278         }
279
280 out_unlock:
281         spin_unlock_bh(&call->lock);
282 out:
283         _leave("");
284 }
285
286 /*
287  * Handle retransmission and deferred ACK/abort generation.
288  */
289 void rxrpc_process_call(struct work_struct *work)
290 {
291         struct rxrpc_call *call =
292                 container_of(work, struct rxrpc_call, processor);
293         rxrpc_serial_t *send_ack;
294         unsigned long now, next, t;
295         unsigned int iterations = 0;
296
297         rxrpc_see_call(call);
298
299         //printk("\n--------------------\n");
300         _enter("{%d,%s,%lx}",
301                call->debug_id, rxrpc_call_states[call->state], call->events);
302
303 recheck_state:
304         /* Limit the number of times we do this before returning to the manager */
305         iterations++;
306         if (iterations > 5)
307                 goto requeue;
308
309         if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) {
310                 rxrpc_send_abort_packet(call);
311                 goto recheck_state;
312         }
313
314         if (call->state == RXRPC_CALL_COMPLETE) {
315                 del_timer_sync(&call->timer);
316                 goto out_put;
317         }
318
319         /* Work out if any timeouts tripped */
320         now = jiffies;
321         t = READ_ONCE(call->expect_rx_by);
322         if (time_after_eq(now, t)) {
323                 trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now);
324                 set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
325         }
326
327         t = READ_ONCE(call->expect_req_by);
328         if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST &&
329             time_after_eq(now, t)) {
330                 trace_rxrpc_timer(call, rxrpc_timer_exp_idle, now);
331                 set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
332         }
333
334         t = READ_ONCE(call->expect_term_by);
335         if (time_after_eq(now, t)) {
336                 trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now);
337                 set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
338         }
339
340         t = READ_ONCE(call->ack_at);
341         if (time_after_eq(now, t)) {
342                 trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now);
343                 cmpxchg(&call->ack_at, t, now + MAX_JIFFY_OFFSET);
344                 set_bit(RXRPC_CALL_EV_ACK, &call->events);
345         }
346
347         t = READ_ONCE(call->ack_lost_at);
348         if (time_after_eq(now, t)) {
349                 trace_rxrpc_timer(call, rxrpc_timer_exp_lost_ack, now);
350                 cmpxchg(&call->ack_lost_at, t, now + MAX_JIFFY_OFFSET);
351                 set_bit(RXRPC_CALL_EV_ACK_LOST, &call->events);
352         }
353
354         t = READ_ONCE(call->keepalive_at);
355         if (time_after_eq(now, t)) {
356                 trace_rxrpc_timer(call, rxrpc_timer_exp_keepalive, now);
357                 cmpxchg(&call->keepalive_at, t, now + MAX_JIFFY_OFFSET);
358                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, true,
359                                   rxrpc_propose_ack_ping_for_keepalive);
360                 set_bit(RXRPC_CALL_EV_PING, &call->events);
361         }
362
363         t = READ_ONCE(call->ping_at);
364         if (time_after_eq(now, t)) {
365                 trace_rxrpc_timer(call, rxrpc_timer_exp_ping, now);
366                 cmpxchg(&call->ping_at, t, now + MAX_JIFFY_OFFSET);
367                 set_bit(RXRPC_CALL_EV_PING, &call->events);
368         }
369
370         t = READ_ONCE(call->resend_at);
371         if (time_after_eq(now, t)) {
372                 trace_rxrpc_timer(call, rxrpc_timer_exp_resend, now);
373                 cmpxchg(&call->resend_at, t, now + MAX_JIFFY_OFFSET);
374                 set_bit(RXRPC_CALL_EV_RESEND, &call->events);
375         }
376
377         /* Process events */
378         if (test_and_clear_bit(RXRPC_CALL_EV_EXPIRED, &call->events)) {
379                 if (test_bit(RXRPC_CALL_RX_HEARD, &call->flags) &&
380                     (int)call->conn->hi_serial - (int)call->rx_serial > 0) {
381                         trace_rxrpc_call_reset(call);
382                         rxrpc_abort_call("EXP", call, 0, RX_USER_ABORT, -ECONNRESET);
383                 } else {
384                         rxrpc_abort_call("EXP", call, 0, RX_USER_ABORT, -ETIME);
385                 }
386                 set_bit(RXRPC_CALL_EV_ABORT, &call->events);
387                 goto recheck_state;
388         }
389
390         send_ack = NULL;
391         if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events)) {
392                 call->acks_lost_top = call->tx_top;
393                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false,
394                                   rxrpc_propose_ack_ping_for_lost_ack);
395                 send_ack = &call->acks_lost_ping;
396         }
397
398         if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events) ||
399             send_ack) {
400                 if (call->ackr_reason) {
401                         rxrpc_send_ack_packet(call, false, send_ack);
402                         goto recheck_state;
403                 }
404         }
405
406         if (test_and_clear_bit(RXRPC_CALL_EV_PING, &call->events)) {
407                 rxrpc_send_ack_packet(call, true, NULL);
408                 goto recheck_state;
409         }
410
411         if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events)) {
412                 rxrpc_resend(call, now);
413                 goto recheck_state;
414         }
415
416         /* Make sure the timer is restarted */
417         next = call->expect_rx_by;
418
419 #define set(T) { t = READ_ONCE(T); if (time_before(t, next)) next = t; }
420
421         set(call->expect_req_by);
422         set(call->expect_term_by);
423         set(call->ack_at);
424         set(call->ack_lost_at);
425         set(call->resend_at);
426         set(call->keepalive_at);
427         set(call->ping_at);
428
429         now = jiffies;
430         if (time_after_eq(now, next))
431                 goto recheck_state;
432
433         rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart);
434
435         /* other events may have been raised since we started checking */
436         if (call->events && call->state < RXRPC_CALL_COMPLETE)
437                 goto requeue;
438
439 out_put:
440         rxrpc_put_call(call, rxrpc_call_put);
441 out:
442         _leave("");
443         return;
444
445 requeue:
446         __rxrpc_queue_call(call);
447         goto out;
448 }