[PATCH net-next 05/13] rxrpc: Allow a delay to be injected into packet reception
David Howells
dhowells at redhat.com
Tue Jan 31 09:12:19 PST 2023
If CONFIG_AF_RXRPC_DEBUG_RX_DELAY=y, then a delay is injected between
packets and errors being received and them being made available to the
processing code, thereby allowing the RTT to be artificially increased.
Signed-off-by: David Howells <dhowells at redhat.com>
cc: Marc Dionne <marc.dionne at auristor.com>
cc: linux-afs at lists.infradead.org
---
net/rxrpc/Kconfig | 9 ++++++++
net/rxrpc/ar-internal.h | 6 +++++
net/rxrpc/io_thread.c | 48 +++++++++++++++++++++++++++++++++++++++-
net/rxrpc/local_object.c | 6 +++++
net/rxrpc/misc.c | 7 ++++++
net/rxrpc/sysctl.c | 17 +++++++++++++-
6 files changed, 91 insertions(+), 2 deletions(-)
diff --git a/net/rxrpc/Kconfig b/net/rxrpc/Kconfig
index 7ae023b37a83..a20986806fea 100644
--- a/net/rxrpc/Kconfig
+++ b/net/rxrpc/Kconfig
@@ -36,6 +36,15 @@ config AF_RXRPC_INJECT_LOSS
Say Y here to inject packet loss by discarding some received and some
transmitted packets.
+config AF_RXRPC_INJECT_RX_DELAY
+ bool "Inject delay into packet reception"
+ depends on SYSCTL
+ help
+ Say Y here to inject a delay into packet reception, allowing an
+ extended RTT time to be modelled. The delay can be configured using
+ /proc/sys/net/rxrpc/rxrpc_inject_rx_delay, setting a number of
+ milliseconds up to 0.5s (note that the granularity is actually in
+ jiffies).
config AF_RXRPC_DEBUG
bool "RxRPC dynamic debugging"
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 808c08cb2ae5..bfae4a87626f 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -285,6 +285,9 @@ struct rxrpc_local {
struct completion io_thread_ready; /* Indication that the I/O thread started */
struct rxrpc_sock *service; /* Service(s) listening on this endpoint */
struct rw_semaphore defrag_sem; /* control re-enablement of IP DF bit */
+#ifdef CONFIG_AF_RXRPC_INJECT_RX_DELAY
+ struct sk_buff_head rx_delay_queue; /* Delay injection queue */
+#endif
struct sk_buff_head rx_queue; /* Received packets */
struct list_head conn_attend_q; /* Conns requiring immediate attention */
struct list_head call_attend_q; /* Calls requiring immediate attention */
@@ -1109,6 +1112,9 @@ extern unsigned long rxrpc_idle_ack_delay;
extern unsigned int rxrpc_rx_window_size;
extern unsigned int rxrpc_rx_mtu;
extern unsigned int rxrpc_rx_jumbo_max;
+#ifdef CONFIG_AF_RXRPC_INJECT_RX_DELAY
+extern unsigned long rxrpc_inject_rx_delay;
+#endif
/*
* net_ns.c
diff --git a/net/rxrpc/io_thread.c b/net/rxrpc/io_thread.c
index 9e9dfb2fc559..4a3a08a0e2cd 100644
--- a/net/rxrpc/io_thread.c
+++ b/net/rxrpc/io_thread.c
@@ -25,6 +25,7 @@ static int rxrpc_input_packet_on_conn(struct rxrpc_connection *conn,
*/
int rxrpc_encap_rcv(struct sock *udp_sk, struct sk_buff *skb)
{
+ struct sk_buff_head *rx_queue;
struct rxrpc_local *local = rcu_dereference_sk_user_data(udp_sk);
if (unlikely(!local)) {
@@ -36,7 +37,16 @@ int rxrpc_encap_rcv(struct sock *udp_sk, struct sk_buff *skb)
skb->mark = RXRPC_SKB_MARK_PACKET;
rxrpc_new_skb(skb, rxrpc_skb_new_encap_rcv);
- skb_queue_tail(&local->rx_queue, skb);
+ rx_queue = &local->rx_queue;
+#ifdef CONFIG_AF_RXRPC_INJECT_RX_DELAY
+ if (rxrpc_inject_rx_delay ||
+ !skb_queue_empty(&local->rx_delay_queue)) {
+ skb->tstamp = ktime_add_ms(skb->tstamp, rxrpc_inject_rx_delay);
+ rx_queue = &local->rx_delay_queue;
+ }
+#endif
+
+ skb_queue_tail(rx_queue, skb);
rxrpc_wake_up_io_thread(local);
return 0;
}
@@ -407,6 +417,9 @@ int rxrpc_io_thread(void *data)
struct rxrpc_local *local = data;
struct rxrpc_call *call;
struct sk_buff *skb;
+#ifdef CONFIG_AF_RXRPC_INJECT_RX_DELAY
+ ktime_t now;
+#endif
bool should_stop;
complete(&local->io_thread_ready);
@@ -481,6 +494,17 @@ int rxrpc_io_thread(void *data)
continue;
}
+ /* Inject a delay into packets if requested. */
+#ifdef CONFIG_AF_RXRPC_INJECT_RX_DELAY
+ now = ktime_get_real();
+ while ((skb = skb_peek(&local->rx_delay_queue))) {
+ if (ktime_before(now, skb->tstamp))
+ break;
+ skb = skb_dequeue(&local->rx_delay_queue);
+ skb_queue_tail(&local->rx_queue, skb);
+ }
+#endif
+
if (!skb_queue_empty(&local->rx_queue)) {
spin_lock_irq(&local->rx_queue.lock);
skb_queue_splice_tail_init(&local->rx_queue, &rx_queue);
@@ -502,6 +526,28 @@ int rxrpc_io_thread(void *data)
if (should_stop)
break;
+
+#ifdef CONFIG_AF_RXRPC_INJECT_RX_DELAY
+ skb = skb_peek(&local->rx_delay_queue);
+ if (skb) {
+ unsigned long timeout;
+ ktime_t tstamp = skb->tstamp;
+ ktime_t now = ktime_get_real();
+ s64 delay_ns = ktime_to_ns(ktime_sub(tstamp, now));
+
+ if (delay_ns <= 0) {
+ __set_current_state(TASK_RUNNING);
+ continue;
+ }
+
+ timeout = nsecs_to_jiffies(delay_ns);
+ timeout = max(timeout, 1UL);
+ schedule_timeout(timeout);
+ __set_current_state(TASK_RUNNING);
+ continue;
+ }
+#endif
+
schedule();
}
diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c
index b8eaca5d9f22..07d83a4e5841 100644
--- a/net/rxrpc/local_object.c
+++ b/net/rxrpc/local_object.c
@@ -110,6 +110,9 @@ static struct rxrpc_local *rxrpc_alloc_local(struct net *net,
INIT_HLIST_NODE(&local->link);
init_rwsem(&local->defrag_sem);
init_completion(&local->io_thread_ready);
+#ifdef CONFIG_AF_RXRPC_INJECT_RX_DELAY
+ skb_queue_head_init(&local->rx_delay_queue);
+#endif
skb_queue_head_init(&local->rx_queue);
INIT_LIST_HEAD(&local->conn_attend_q);
INIT_LIST_HEAD(&local->call_attend_q);
@@ -434,6 +437,9 @@ void rxrpc_destroy_local(struct rxrpc_local *local)
/* At this point, there should be no more packets coming in to the
* local endpoint.
*/
+#ifdef CONFIG_AF_RXRPC_INJECT_RX_DELAY
+ rxrpc_purge_queue(&local->rx_delay_queue);
+#endif
rxrpc_purge_queue(&local->rx_queue);
rxrpc_purge_client_connections(local);
}
diff --git a/net/rxrpc/misc.c b/net/rxrpc/misc.c
index 056c428d8bf3..825b81183046 100644
--- a/net/rxrpc/misc.c
+++ b/net/rxrpc/misc.c
@@ -53,3 +53,10 @@ unsigned int rxrpc_rx_mtu = 5692;
* sender that we're willing to handle.
*/
unsigned int rxrpc_rx_jumbo_max = 4;
+
+#ifdef CONFIG_AF_RXRPC_INJECT_RX_DELAY
+/*
+ * The delay to inject into packet reception.
+ */
+unsigned long rxrpc_inject_rx_delay;
+#endif
diff --git a/net/rxrpc/sysctl.c b/net/rxrpc/sysctl.c
index cde3224a5cd2..ecaeb4ecfb58 100644
--- a/net/rxrpc/sysctl.c
+++ b/net/rxrpc/sysctl.c
@@ -17,6 +17,9 @@ static const unsigned int n_65535 = 65535;
static const unsigned int n_max_acks = 255;
static const unsigned long one_jiffy = 1;
static const unsigned long max_jiffies = MAX_JIFFY_OFFSET;
+#ifdef CONFIG_AF_RXRPC_INJECT_RX_DELAY
+static const unsigned long max_500 = 500;
+#endif
/*
* RxRPC operating parameters.
@@ -63,6 +66,19 @@ static struct ctl_table rxrpc_sysctl_table[] = {
.extra2 = (void *)&max_jiffies,
},
+ /* Values used in milliseconds */
+#ifdef CONFIG_AF_RXRPC_INJECT_RX_DELAY
+ {
+ .procname = "inject_rx_delay",
+ .data = &rxrpc_inject_rx_delay,
+ .maxlen = sizeof(unsigned long),
+ .mode = 0644,
+ .proc_handler = proc_doulongvec_minmax,
+ .extra1 = (void *)SYSCTL_LONG_ZERO,
+ .extra2 = (void *)&max_500,
+ },
+#endif
+
/* Non-time values */
{
.procname = "reap_client_conns",
@@ -109,7 +125,6 @@ static struct ctl_table rxrpc_sysctl_table[] = {
.extra1 = (void *)SYSCTL_ONE,
.extra2 = (void *)&four,
},
-
{ }
};
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