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Date: Thu, 06 Oct 2016 11:04:38 +0100
From: David Howells <dhowells@...hat.com>
To: netdev@...r.kernel.org
Cc: dhowells@...hat.com, linux-afs@...ts.infradead.org,
linux-kernel@...r.kernel.org
Subject: [PATCH net 06/13] rxrpc: Fix loss of PING RESPONSE ACK production
due to PING ACKs
Separate the output of PING ACKs from the output of other sorts of ACK so
that if we receive a PING ACK and schedule transmission of a PING RESPONSE
ACK, the response doesn't get cancelled by a PING ACK we happen to be
scheduling transmission of at the same time.
If a PING RESPONSE gets lost, the other side might just sit there waiting
for it and refuse to proceed otherwise.
Signed-off-by: David Howells <dhowells@...hat.com>
---
net/rxrpc/ar-internal.h | 12 +++++++++---
net/rxrpc/call_event.c | 48 +++++++++++++++++++++++++++++++++++++++++++----
net/rxrpc/call_object.c | 1 +
net/rxrpc/input.c | 4 ++--
net/rxrpc/misc.c | 2 +-
net/rxrpc/output.c | 38 ++++++++++++++++++++++---------------
net/rxrpc/recvmsg.c | 4 ++--
net/rxrpc/sendmsg.c | 2 +-
8 files changed, 82 insertions(+), 29 deletions(-)
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index ef849a12a0f0..b56676be07c7 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -398,6 +398,7 @@ enum rxrpc_call_flag {
RXRPC_CALL_EXPOSED, /* The call was exposed to the world */
RXRPC_CALL_RX_LAST, /* Received the last packet (at rxtx_top) */
RXRPC_CALL_TX_LAST, /* Last packet in Tx buffer (at rxtx_top) */
+ RXRPC_CALL_SEND_PING, /* A ping will need to be sent */
RXRPC_CALL_PINGING, /* Ping in process */
RXRPC_CALL_RETRANS_TIMEOUT, /* Retransmission due to timeout occurred */
};
@@ -410,6 +411,7 @@ enum rxrpc_call_event {
RXRPC_CALL_EV_ABORT, /* need to generate abort */
RXRPC_CALL_EV_TIMER, /* Timer expired */
RXRPC_CALL_EV_RESEND, /* Tx resend required */
+ RXRPC_CALL_EV_PING, /* Ping send required */
};
/*
@@ -466,6 +468,7 @@ struct rxrpc_call {
struct rxrpc_sock __rcu *socket; /* socket responsible */
ktime_t ack_at; /* When deferred ACK needs to happen */
ktime_t resend_at; /* When next resend needs to happen */
+ ktime_t ping_at; /* When next to send a ping */
ktime_t expire_at; /* When the call times out */
struct timer_list timer; /* Combined event timer */
struct work_struct processor; /* Event processor */
@@ -558,8 +561,10 @@ struct rxrpc_call {
rxrpc_seq_t ackr_prev_seq; /* previous sequence number received */
rxrpc_seq_t ackr_consumed; /* Highest packet shown consumed */
rxrpc_seq_t ackr_seen; /* Highest packet shown seen */
- rxrpc_serial_t ackr_ping; /* Last ping sent */
- ktime_t ackr_ping_time; /* Time last ping sent */
+
+ /* ping management */
+ rxrpc_serial_t ping_serial; /* Last ping sent */
+ ktime_t ping_time; /* Time last ping sent */
/* transmission-phase ACK management */
ktime_t acks_latest_ts; /* Timestamp of latest ACK received */
@@ -730,6 +735,7 @@ enum rxrpc_timer_trace {
rxrpc_timer_init_for_reply,
rxrpc_timer_expired,
rxrpc_timer_set_for_ack,
+ rxrpc_timer_set_for_ping,
rxrpc_timer_set_for_resend,
rxrpc_timer_set_for_send,
rxrpc_timer__nr_trace
@@ -1068,7 +1074,7 @@ extern const s8 rxrpc_ack_priority[];
/*
* output.c
*/
-int rxrpc_send_ack_packet(struct rxrpc_call *);
+int rxrpc_send_ack_packet(struct rxrpc_call *, bool);
int rxrpc_send_abort_packet(struct rxrpc_call *);
int rxrpc_send_data_packet(struct rxrpc_call *, struct sk_buff *, bool);
void rxrpc_reject_packets(struct rxrpc_local *);
diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c
index e313099860d5..eeea9602cb89 100644
--- a/net/rxrpc/call_event.c
+++ b/net/rxrpc/call_event.c
@@ -54,6 +54,14 @@ void rxrpc_set_timer(struct rxrpc_call *call, enum rxrpc_timer_trace why,
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;
@@ -78,6 +86,27 @@ out:
}
/*
+ * Propose a PING ACK be sent.
+ */
+static void rxrpc_propose_ping(struct rxrpc_call *call,
+ bool immediate, bool background)
+{
+ if (immediate) {
+ if (background &&
+ !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);
+
+ if (ktime_before(ping_at, call->ping_at)) {
+ call->ping_at = ping_at;
+ rxrpc_set_timer(call, rxrpc_timer_set_for_ping, now);
+ }
+ }
+}
+
+/*
* propose an ACK be sent
*/
static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
@@ -90,6 +119,14 @@ static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
ktime_t now, ack_at;
s8 prior = rxrpc_ack_priority[ack_reason];
+ /* Pings are handled specially because we don't want to accidentally
+ * lose a ping response by subsuming it into a ping.
+ */
+ if (ack_reason == RXRPC_ACK_PING) {
+ rxrpc_propose_ping(call, immediate, background);
+ goto trace;
+ }
+
/* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
* numbers, but we don't alter the timeout.
*/
@@ -125,7 +162,6 @@ static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
expiry = rxrpc_soft_ack_delay;
break;
- case RXRPC_ACK_PING:
case RXRPC_ACK_IDLE:
if (rxrpc_idle_ack_delay < expiry)
expiry = rxrpc_idle_ack_delay;
@@ -253,7 +289,7 @@ static void rxrpc_resend(struct rxrpc_call *call, ktime_t now)
goto out;
rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, false,
rxrpc_propose_ack_ping_for_lost_ack);
- rxrpc_send_ack_packet(call);
+ rxrpc_send_ack_packet(call, true);
goto out;
}
@@ -345,13 +381,17 @@ recheck_state:
}
if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events)) {
- call->ack_at = call->expire_at;
if (call->ackr_reason) {
- rxrpc_send_ack_packet(call);
+ rxrpc_send_ack_packet(call, false);
goto recheck_state;
}
}
+ if (test_and_clear_bit(RXRPC_CALL_EV_PING, &call->events)) {
+ rxrpc_send_ack_packet(call, true);
+ goto recheck_state;
+ }
+
if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events)) {
rxrpc_resend(call, now);
goto recheck_state;
diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c
index 07094012ac15..4353a29f3b57 100644
--- a/net/rxrpc/call_object.c
+++ b/net/rxrpc/call_object.c
@@ -205,6 +205,7 @@ static void rxrpc_start_call_timer(struct rxrpc_call *call)
expire_at = ktime_add_ms(now, rxrpc_max_call_lifetime);
call->expire_at = expire_at;
call->ack_at = expire_at;
+ call->ping_at = expire_at;
call->resend_at = expire_at;
call->timer.expires = jiffies + LONG_MAX / 2;
rxrpc_set_timer(call, rxrpc_timer_begin, now);
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index 103d2b0d4690..a6da83f036d6 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -625,9 +625,9 @@ static void rxrpc_input_ping_response(struct rxrpc_call *call,
rxrpc_serial_t ping_serial;
ktime_t ping_time;
- ping_time = call->ackr_ping_time;
+ ping_time = call->ping_time;
smp_rmb();
- ping_serial = call->ackr_ping;
+ ping_serial = call->ping_serial;
if (!test_bit(RXRPC_CALL_PINGING, &call->flags) ||
before(orig_serial, ping_serial))
diff --git a/net/rxrpc/misc.c b/net/rxrpc/misc.c
index 804a88e28739..1cdcba52f83b 100644
--- a/net/rxrpc/misc.c
+++ b/net/rxrpc/misc.c
@@ -93,7 +93,6 @@ const s8 rxrpc_ack_priority[] = {
[RXRPC_ACK_EXCEEDS_WINDOW] = 6,
[RXRPC_ACK_NOSPACE] = 7,
[RXRPC_ACK_PING_RESPONSE] = 8,
- [RXRPC_ACK_PING] = 9,
};
const char rxrpc_ack_names[RXRPC_ACK__INVALID + 1][4] = {
@@ -197,6 +196,7 @@ const char rxrpc_timer_traces[rxrpc_timer__nr_trace][8] = {
[rxrpc_timer_expired] = "*EXPR*",
[rxrpc_timer_init_for_reply] = "IniRpl",
[rxrpc_timer_set_for_ack] = "SetAck",
+ [rxrpc_timer_set_for_ping] = "SetPng",
[rxrpc_timer_set_for_send] = "SetTx ",
[rxrpc_timer_set_for_resend] = "SetRTx",
};
diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index 2dae877c0876..a12cea0cbc05 100644
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -38,7 +38,8 @@ struct rxrpc_abort_buffer {
static size_t rxrpc_fill_out_ack(struct rxrpc_call *call,
struct rxrpc_ack_buffer *pkt,
rxrpc_seq_t *_hard_ack,
- rxrpc_seq_t *_top)
+ rxrpc_seq_t *_top,
+ u8 reason)
{
rxrpc_serial_t serial;
rxrpc_seq_t hard_ack, top, seq;
@@ -58,10 +59,10 @@ static size_t rxrpc_fill_out_ack(struct rxrpc_call *call,
pkt->ack.firstPacket = htonl(hard_ack + 1);
pkt->ack.previousPacket = htonl(call->ackr_prev_seq);
pkt->ack.serial = htonl(serial);
- pkt->ack.reason = call->ackr_reason;
+ pkt->ack.reason = reason;
pkt->ack.nAcks = top - hard_ack;
- if (pkt->ack.reason == RXRPC_ACK_PING)
+ if (reason == RXRPC_ACK_PING)
pkt->whdr.flags |= RXRPC_REQUEST_ACK;
if (after(top, hard_ack)) {
@@ -93,7 +94,7 @@ static size_t rxrpc_fill_out_ack(struct rxrpc_call *call,
/*
* Send an ACK call packet.
*/
-int rxrpc_send_ack_packet(struct rxrpc_call *call)
+int rxrpc_send_ack_packet(struct rxrpc_call *call, bool ping)
{
struct rxrpc_connection *conn = NULL;
struct rxrpc_ack_buffer *pkt;
@@ -102,8 +103,8 @@ int rxrpc_send_ack_packet(struct rxrpc_call *call)
rxrpc_serial_t serial;
rxrpc_seq_t hard_ack, top;
size_t len, n;
- bool ping = false;
int ret;
+ u8 reason;
spin_lock_bh(&call->lock);
if (call->conn)
@@ -136,14 +137,18 @@ int rxrpc_send_ack_packet(struct rxrpc_call *call)
pkt->whdr.serviceId = htons(call->service_id);
spin_lock_bh(&call->lock);
- if (!call->ackr_reason) {
- spin_unlock_bh(&call->lock);
- ret = 0;
- goto out;
+ if (ping) {
+ reason = RXRPC_ACK_PING;
+ } else {
+ reason = call->ackr_reason;
+ if (!call->ackr_reason) {
+ spin_unlock_bh(&call->lock);
+ ret = 0;
+ goto out;
+ }
+ call->ackr_reason = 0;
}
- ping = (call->ackr_reason == RXRPC_ACK_PING);
- n = rxrpc_fill_out_ack(call, pkt, &hard_ack, &top);
- call->ackr_reason = 0;
+ n = rxrpc_fill_out_ack(call, pkt, &hard_ack, &top, reason);
spin_unlock_bh(&call->lock);
@@ -161,7 +166,7 @@ int rxrpc_send_ack_packet(struct rxrpc_call *call)
pkt->ack.reason, pkt->ack.nAcks);
if (ping) {
- call->ackr_ping = serial;
+ call->ping_serial = serial;
smp_wmb();
/* We need to stick a time in before we send the packet in case
* the reply gets back before kernel_sendmsg() completes - but
@@ -170,18 +175,19 @@ int rxrpc_send_ack_packet(struct rxrpc_call *call)
* the packet transmission is more likely to happen towards the
* end of the kernel_sendmsg() call.
*/
- call->ackr_ping_time = ktime_get_real();
+ call->ping_time = ktime_get_real();
set_bit(RXRPC_CALL_PINGING, &call->flags);
trace_rxrpc_rtt_tx(call, rxrpc_rtt_tx_ping, serial);
}
ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 2, len);
if (ping)
- call->ackr_ping_time = ktime_get_real();
+ call->ping_time = ktime_get_real();
if (call->state < RXRPC_CALL_COMPLETE) {
if (ret < 0) {
- clear_bit(RXRPC_CALL_PINGING, &call->flags);
+ if (ping)
+ clear_bit(RXRPC_CALL_PINGING, &call->flags);
rxrpc_propose_ACK(call, pkt->ack.reason,
ntohs(pkt->ack.maxSkew),
ntohl(pkt->ack.serial),
diff --git a/net/rxrpc/recvmsg.c b/net/rxrpc/recvmsg.c
index 11723bc1c783..3fa7771c2a9d 100644
--- a/net/rxrpc/recvmsg.c
+++ b/net/rxrpc/recvmsg.c
@@ -143,7 +143,7 @@ static void rxrpc_end_rx_phase(struct rxrpc_call *call, rxrpc_serial_t serial)
if (call->state == RXRPC_CALL_CLIENT_RECV_REPLY) {
rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, 0, serial, true, false,
rxrpc_propose_ack_terminal_ack);
- rxrpc_send_ack_packet(call);
+ rxrpc_send_ack_packet(call, false);
}
write_lock_bh(&call->state_lock);
@@ -212,7 +212,7 @@ static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
true, false,
rxrpc_propose_ack_rotate_rx);
if (call->ackr_reason)
- rxrpc_send_ack_packet(call);
+ rxrpc_send_ack_packet(call, false);
}
}
diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index 901b28ceeff4..55a2fb2cfc2f 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -197,7 +197,7 @@ static int rxrpc_send_data(struct rxrpc_sock *rx,
do {
/* Check to see if there's a ping ACK to reply to. */
if (call->ackr_reason == RXRPC_ACK_PING_RESPONSE)
- rxrpc_send_ack_packet(call);
+ rxrpc_send_ack_packet(call, false);
if (!skb) {
size_t size, chunk, max, space;
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