rxrpc: Fix call timeouts

Fix the rxrpc call expiration timeouts and make them settable from
userspace.  By analogy with other rx implementations, there should be three
timeouts:

 (1) "Normal timeout"

     This is set for all calls and is triggered if we haven't received any
     packets from the peer in a while.  It is measured from the last time
     we received any packet on that call.  This is not reset by any
     connection packets (such as CHALLENGE/RESPONSE packets).

     If a service operation takes a long time, the server should generate
     PING ACKs at a duration that's substantially less than the normal
     timeout so is to keep both sides alive.  This is set at 1/6 of normal
     timeout.

 (2) "Idle timeout"

     This is set only for a service call and is triggered if we stop
     receiving the DATA packets that comprise the request data.  It is
     measured from the last time we received a DATA packet.

 (3) "Hard timeout"

     This can be set for a call and specified the maximum lifetime of that
     call.  It should not be specified by default.  Some operations (such
     as volume transfer) take a long time.

Allow userspace to set/change the timeouts on a call with sendmsg, using a
control message:

	RXRPC_SET_CALL_TIMEOUTS

The data to the message is a number of 32-bit words, not all of which need
be given:

	u32 hard_timeout;	/* sec from first packet */
	u32 idle_timeout;	/* msec from packet Rx */
	u32 normal_timeout;	/* msec from data Rx */

This can be set in combination with any other sendmsg() that affects a
call.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 84 insertions, 95 deletions

diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c
index 3574508baf9a..c14395d5ad8c 100644
--- a/net/rxrpc/call_event.c
+++ b/net/rxrpc/call_event.c
@@ -22,80 +22,6 @@
 #include "ar-internal.h"
 
 /*
- * Set the timer
- */
-void __rxrpc_set_timer(struct rxrpc_call *call, enum rxrpc_timer_trace why,
-		       ktime_t now)
-{
-	unsigned long t_j, now_j = jiffies;
-	ktime_t t;
-	bool queue = false;
-
-	if (call->state < RXRPC_CALL_COMPLETE) {
-		t = call->expire_at;
-		if (!ktime_after(t, now)) {
-			trace_rxrpc_timer(call, why, now, now_j);
-			queue = true;
-			goto out;
-		}
-
-		if (!ktime_after(call->resend_at, now)) {
-			call->resend_at = call->expire_at;
-			if (!test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
-				queue = true;
-		} else if (ktime_before(call->resend_at, t)) {
-			t = call->resend_at;
-		}
-
-		if (!ktime_after(call->ack_at, now)) {
-			call->ack_at = call->expire_at;
-			if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events))
-				queue = true;
-		} else if (ktime_before(call->ack_at, t)) {
-			t = call->ack_at;
-		}
-
-		if (!ktime_after(call->ping_at, now)) {
-			call->ping_at = call->expire_at;
-			if (!test_and_set_bit(RXRPC_CALL_EV_PING, &call->events))
-				queue = true;
-		} else if (ktime_before(call->ping_at, t)) {
-			t = call->ping_at;
-		}
-
-		t_j = nsecs_to_jiffies(ktime_to_ns(ktime_sub(t, now)));
-		t_j += jiffies;
-
-		/* We have to make sure that the calculated jiffies value falls
-		 * at or after the nsec value, or we may loop ceaselessly
-		 * because the timer times out, but we haven't reached the nsec
-		 * timeout yet.
-		 */
-		t_j++;
-
-		if (call->timer.expires != t_j || !timer_pending(&call->timer)) {
-			mod_timer(&call->timer, t_j);
-			trace_rxrpc_timer(call, why, now, now_j);
-		}
-	}
-
-out:
-	if (queue)
-		rxrpc_queue_call(call);
-}
-
-/*
- * Set the timer
- */
-void rxrpc_set_timer(struct rxrpc_call *call, enum rxrpc_timer_trace why,
-		     ktime_t now)
-{
-	read_lock_bh(&call->state_lock);
-	__rxrpc_set_timer(call, why, now);
-	read_unlock_bh(&call->state_lock);
-}
-
-/*
  * Propose a PING ACK be sent.
  */
 static void rxrpc_propose_ping(struct rxrpc_call *call,
@@ -106,12 +32,13 @@ static void rxrpc_propose_ping(struct rxrpc_call *call,
 		    !test_and_set_bit(RXRPC_CALL_EV_PING, &call->events))
 			rxrpc_queue_call(call);
 	} else {
-		ktime_t now = ktime_get_real();
-		ktime_t ping_at = ktime_add_ms(now, rxrpc_idle_ack_delay);
+		unsigned long now = jiffies;
+		unsigned long ping_at = now + rxrpc_idle_ack_delay;
 
-		if (ktime_before(ping_at, call->ping_at)) {
-			call->ping_at = ping_at;
-			rxrpc_set_timer(call, rxrpc_timer_set_for_ping, now);
+		if (time_before(ping_at, call->ping_at)) {
+			WRITE_ONCE(call->ping_at, ping_at);
+			rxrpc_reduce_call_timer(call, ping_at, now,
+						rxrpc_timer_set_for_ping);
 		}
 	}
 }
@@ -125,8 +52,7 @@ static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
 				enum rxrpc_propose_ack_trace why)
 {
 	enum rxrpc_propose_ack_outcome outcome = rxrpc_propose_ack_use;
-	unsigned int expiry = rxrpc_soft_ack_delay;
-	ktime_t now, ack_at;
+	unsigned long now, ack_at, expiry = rxrpc_soft_ack_delay;
 	s8 prior = rxrpc_ack_priority[ack_reason];
 
 	/* Pings are handled specially because we don't want to accidentally
@@ -190,11 +116,12 @@ static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
 		    background)
 			rxrpc_queue_call(call);
 	} else {
-		now = ktime_get_real();
-		ack_at = ktime_add_ms(now, expiry);
-		if (ktime_before(ack_at, call->ack_at)) {
-			call->ack_at = ack_at;
-			rxrpc_set_timer(call, rxrpc_timer_set_for_ack, now);
+		now = jiffies;
+		ack_at = jiffies + expiry;
+		if (time_before(ack_at, call->ack_at)) {
+			WRITE_ONCE(call->ack_at, ack_at);
+			rxrpc_reduce_call_timer(call, ack_at, now,
+						rxrpc_timer_set_for_ack);
 		}
 	}
 
@@ -227,18 +154,20 @@ static void rxrpc_congestion_timeout(struct rxrpc_call *call)
 /*
  * Perform retransmission of NAK'd and unack'd packets.
  */
-static void rxrpc_resend(struct rxrpc_call *call, ktime_t now)
+static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j)
 {
 	struct rxrpc_skb_priv *sp;
 	struct sk_buff *skb;
+	unsigned long resend_at;
 	rxrpc_seq_t cursor, seq, top;
-	ktime_t max_age, oldest, ack_ts;
+	ktime_t now, max_age, oldest, ack_ts;
 	int ix;
 	u8 annotation, anno_type, retrans = 0, unacked = 0;
 
 	_enter("{%d,%d}", call->tx_hard_ack, call->tx_top);
 
-	max_age = ktime_sub_ms(now, rxrpc_resend_timeout);
+	now = ktime_get_real();
+	max_age = ktime_sub_ms(now, rxrpc_resend_timeout * 1000 / HZ);
 
 	spin_lock_bh(&call->lock);
 
@@ -282,7 +211,9 @@ static void rxrpc_resend(struct rxrpc_call *call, ktime_t now)
 				       ktime_to_ns(ktime_sub(skb->tstamp, max_age)));
 	}
 
-	call->resend_at = ktime_add_ms(oldest, rxrpc_resend_timeout);
+	resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(oldest, now)));
+	resend_at += jiffies + rxrpc_resend_timeout;
+	WRITE_ONCE(call->resend_at, resend_at);
 
 	if (unacked)
 		rxrpc_congestion_timeout(call);
@@ -292,7 +223,8 @@ static void rxrpc_resend(struct rxrpc_call *call, ktime_t now)
 	 * retransmitting data.
 	 */
 	if (!retrans) {
-		rxrpc_set_timer(call, rxrpc_timer_set_for_resend, now);
+		rxrpc_reduce_call_timer(call, resend_at, now,
+					rxrpc_timer_set_for_resend);
 		spin_unlock_bh(&call->lock);
 		ack_ts = ktime_sub(now, call->acks_latest_ts);
 		if (ktime_to_ns(ack_ts) < call->peer->rtt)
@@ -364,7 +296,7 @@ void rxrpc_process_call(struct work_struct *work)
 {
 	struct rxrpc_call *call =
 		container_of(work, struct rxrpc_call, processor);
-	ktime_t now;
+	unsigned long now, next, t;
 
 	rxrpc_see_call(call);
 
@@ -384,8 +316,50 @@ recheck_state:
 		goto out_put;
 	}
 
-	now = ktime_get_real();
-	if (ktime_before(call->expire_at, now)) {
+	/* Work out if any timeouts tripped */
+	now = jiffies;
+	t = READ_ONCE(call->expect_rx_by);
+	if (time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now);
+		set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
+	}
+
+	t = READ_ONCE(call->expect_req_by);
+	if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST &&
+	    time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_idle, now);
+		set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
+	}
+
+	t = READ_ONCE(call->expect_term_by);
+	if (time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now);
+		set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
+	}
+
+	t = READ_ONCE(call->ack_at);
+	if (time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now);
+		cmpxchg(&call->ack_at, t, now + MAX_JIFFY_OFFSET);
+		set_bit(RXRPC_CALL_EV_ACK, &call->events);
+	}
+
+	t = READ_ONCE(call->ping_at);
+	if (time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_ping, now);
+		cmpxchg(&call->ping_at, t, now + MAX_JIFFY_OFFSET);
+		set_bit(RXRPC_CALL_EV_PING, &call->events);
+	}
+
+	t = READ_ONCE(call->resend_at);
+	if (time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_resend, now);
+		cmpxchg(&call->resend_at, t, now + MAX_JIFFY_OFFSET);
+		set_bit(RXRPC_CALL_EV_RESEND, &call->events);
+	}
+
+	/* Process events */
+	if (test_and_clear_bit(RXRPC_CALL_EV_EXPIRED, &call->events)) {
 		rxrpc_abort_call("EXP", call, 0, RX_USER_ABORT, -ETIME);
 		set_bit(RXRPC_CALL_EV_ABORT, &call->events);
 		goto recheck_state;
@@ -408,7 +382,22 @@ recheck_state:
 		goto recheck_state;
 	}
 
-	rxrpc_set_timer(call, rxrpc_timer_set_for_resend, now);
+	/* Make sure the timer is restarted */
+	next = call->expect_rx_by;
+
+#define set(T) { t = READ_ONCE(T); if (time_before(t, next)) next = t; }
+	
+	set(call->expect_req_by);
+	set(call->expect_term_by);
+	set(call->ack_at);
+	set(call->resend_at);
+	set(call->ping_at);
+
+	now = jiffies;
+	if (time_after_eq(now, next))
+		goto recheck_state;
+
+	rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart);
 
 	/* other events may have been raised since we started checking */
 	if (call->events && call->state < RXRPC_CALL_COMPLETE) {