Merge branch 'nh-flushing'

Ido Schimmel says:

====================
nexthop: Support large scale nexthop flushing

Patch #1 fixes a day-one bug in the nexthop code and allows "ip nexthop
flush" to work correctly with large number of nexthops that do not fit
in a single-part dump.

Patch #2 adds a test case.

Targeting at net-next since this use case never worked, the flow is
pretty obscure and such a large number of nexthops is unlikely to be
used in any real-world scenario.

Tested with fib_nexthops.sh:

Tests passed: 219
Tests failed:   0
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/nexthop.c

@@ -3140,26 +3140,24 @@ static int rtm_dump_walk_nexthops(struct sk_buff *skb,
 				  void *data)
 {
 	struct rb_node *node;
-	int idx = 0, s_idx;
+	int s_idx;
 	int err;
 
 	s_idx = ctx->idx;
 	for (node = rb_first(root); node; node = rb_next(node)) {
 		struct nexthop *nh;
 
-		if (idx < s_idx)
-			goto cont;
-
 		nh = rb_entry(node, struct nexthop, rb_node);
-		ctx->idx = idx;
+		if (nh->id < s_idx)
+			continue;
+
+		ctx->idx = nh->id;
 		err = nh_cb(skb, cb, nh, data);
 		if (err)
 			return err;
-cont:
-		idx++;
 	}
 
-	ctx->idx = idx;
+	ctx->idx++;
 	return 0;
 }
 

tools/testing/selftests/net/fib_nexthops.sh

@@ -1933,6 +1933,21 @@ basic()
 	log_test $? 2 "Nexthop group and blackhole"
 
 	$IP nexthop flush >/dev/null 2>&1
+
+	# Test to ensure that flushing with a multi-part nexthop dump works as
+	# expected.
+	local batch_file=$(mktemp)
+
+	for i in $(seq 1 $((64 * 1024))); do
+		echo "nexthop add id $i blackhole" >> $batch_file
+	done
+
+	$IP -b $batch_file
+	$IP nexthop flush >/dev/null 2>&1
+	[[ $($IP nexthop | wc -l) -eq 0 ]]
+	log_test $? 0 "Large scale nexthop flushing"
+
+	rm $batch_file
 }
 
 check_nexthop_buckets_balance()