[PATCH 6/8] flow, tcp: Add handling for per-flow timers

tcp_timer() scans the flow table so that it can run tcp_splice_timer() on
each spliced connection.  More generally, other flow types might want to
run similar timers in future.

We could add a flow_timer() analagous to tcp_timer(), udp_timer() etc.
However, this would need to scan the flow table, which we would have just
done in flow_defer_handler().  We'd prefer to just scan the flow table
once, dispatching both per-flow deferred events and per-flow timed events
if necessary.

So, extend flow_defer_handler() to do this.  For now we use the same timer
interval for all flow types (1s).  We can make that more flexible in future
if we need to.

Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
 flow.c  | 13 +++++++++++--
 flow.h  |  4 +++-
 passt.c |  7 ++++---
 passt.h |  2 ++
 tcp.c   |  6 ------
 5 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/flow.c b/flow.c
index 0a0402d..39166ae 100644
--- a/flow.c
+++ b/flow.c
@@ -85,13 +85,20 @@ void flow_log_(const struct flow_common *f, int pri, const char *fmt,
...)
 }
 
 /**
- * flow_defer_handler() - Handler for per-flow deferred tasks
+ * flow_defer_handler() - Handler for per-flow deferred and timed tasks
  * @c:		Execution context
+ * @now:	Current timestamp
  */
-void flow_defer_handler(struct ctx *c)
+void flow_defer_handler(struct ctx *c, const struct timespec *now)
 {
+	bool timer = false;
 	union flow *flow;
 
+	if (timespec_diff_ms(now, &c->flow_timer_run) >= FLOW_TIMER_INTERVAL) {
+		timer = true;
+		c->flow_timer_run = *now;
+	}
+
 	for (flow = flowtab + c->flow_count - 1; flow >= flowtab; flow--) {
 		switch (flow->f.type) {
 		case FLOW_TCP:
@@ -99,6 +106,8 @@ void flow_defer_handler(struct ctx *c)
 			break;
 		case FLOW_TCP_SPLICE:
 			tcp_splice_flow_defer(c, flow);
+			if (timer)
+				tcp_splice_timer(c, flow);
 			break;
 		default:
 			/* Assume other flow types don't need any handling */
diff --git a/flow.h b/flow.h
index 4733671..c368a69 100644
--- a/flow.h
+++ b/flow.h
@@ -7,6 +7,8 @@
 #ifndef FLOW_H
 #define FLOW_H
 
+#define FLOW_TIMER_INTERVAL		1000	/* ms */
+
 /**
  * enum flow_type - Different types of packet flows we track
  */
@@ -56,7 +58,7 @@ static_assert(sizeof(flow_sidx_t) <= sizeof(uint32_t),
 union flow;
 
 void flow_table_compact(struct ctx *c, union flow *hole);
-void flow_defer_handler(struct ctx *c);
+void flow_defer_handler(struct ctx *c, const struct timespec *now);
 
 void flow_log_(const struct flow_common *f, int pri, const char *fmt, ...)
 	__attribute__((format(printf, 3, 4)));
diff --git a/passt.c b/passt.c
index 5f72a28..870064f 100644
--- a/passt.c
+++ b/passt.c
@@ -53,8 +53,9 @@
 
 #define EPOLL_EVENTS		8
 
-#define __TIMER_INTERVAL	MIN(TCP_TIMER_INTERVAL, UDP_TIMER_INTERVAL)
-#define TIMER_INTERVAL		MIN(__TIMER_INTERVAL, ICMP_TIMER_INTERVAL)
+#define TIMER_INTERVAL__	MIN(TCP_TIMER_INTERVAL, UDP_TIMER_INTERVAL)
+#define TIMER_INTERVAL_		MIN(TIMER_INTERVAL__, ICMP_TIMER_INTERVAL)
+#define TIMER_INTERVAL		MIN(TIMER_INTERVAL_, FLOW_TIMER_INTERVAL)
 
 char pkt_buf[PKT_BUF_BYTES]	__attribute__ ((aligned(PAGE_SIZE)));
 
@@ -103,7 +104,7 @@ static void post_handler(struct ctx *c, const struct timespec *now)
 	/* NOLINTNEXTLINE(bugprone-branch-clone): intervals can be the same */
 	CALL_PROTO_HANDLER(c, now, icmp, ICMP);
 
-	flow_defer_handler(c);
+	flow_defer_handler(c, now);
 #undef CALL_PROTO_HANDLER
 }
 
diff --git a/passt.h b/passt.h
index c74887a..20528d5 100644
--- a/passt.h
+++ b/passt.h
@@ -223,6 +223,7 @@ struct ip6_ctx {
  * @no_copy_routes:	Don't copy all routes when configuring target namespace
  * @no_copy_addrs:	Don't copy all addresses when configuring namespace
  * @flow_count:		Number of tracked packet flows (connections etc.)
+ * @flow_timer_run:	Timestamp of most recent flow timer run
  * @no_tcp:		Disable TCP operation
  * @tcp:		Context for TCP protocol handler
  * @no_tcp:		Disable UDP operation
@@ -283,6 +284,7 @@ struct ctx {
 	int no_copy_addrs;
 
 	unsigned flow_count;
+	struct timespec flow_timer_run;
 
 	int no_tcp;
 	struct tcp_ctx tcp;
diff --git a/tcp.c b/tcp.c
index 0e8e9e3..95ec760 100644
--- a/tcp.c
+++ b/tcp.c
@@ -3163,8 +3163,6 @@ static int tcp_port_rebind_outbound(void *arg)
  */
 void tcp_timer(struct ctx *c, const struct timespec *now)
 {
-	union flow *flow;
-
 	(void)now;
 
 	if (c->mode == MODE_PASTA) {
@@ -3179,10 +3177,6 @@ void tcp_timer(struct ctx *c, const struct timespec *now)
 		}
 	}
 
-	for (flow = flowtab + c->flow_count - 1; flow >= flowtab; flow--)
-		if (flow->f.type == FLOW_TCP_SPLICE)
-			tcp_splice_timer(c, flow);
-
 	tcp_sock_refill_init(c);
 	if (c->mode == MODE_PASTA)
 		tcp_splice_refill(c);
-- 
2.43.0