[PATCH net-next v2 1/6] packet: rollover prepare: move code out of callsites

[Willem de Bruijn <willemb@google.com>]

From: Willem de Bruijn <willemb@google.com>

packet_rcv_fanout calls fanout_demux_rollover twice. Move all rollover
logic into the callee to simplify these callsites, especially with
upcoming changes.

The main differences between the two callsites is that the FLAG
variant tests whether the socket previously selected by another
mode (RR, RND, HASH, ..) has room before migrating flows, whereas the
rollover mode has no original socket to test.

Signed-off-by: Willem de Bruijn <willemb@google.com>
---
 net/packet/af_packet.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 5102c3c..56f9c52 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1318,18 +1318,22 @@ static unsigned int fanout_demux_rnd(struct packet_fanout *f,
 
 static unsigned int fanout_demux_rollover(struct packet_fanout *f,
 					  struct sk_buff *skb,
-					  unsigned int idx, unsigned int skip,
+					  unsigned int idx, bool try_self,
 					  unsigned int num)
 {
 	unsigned int i, j;
 
+	if (try_self && packet_rcv_has_room(pkt_sk(f->arr[idx]), skb))
+		return idx;
+
 	i = j = min_t(int, f->next[idx], num - 1);
 	do {
-		if (i != skip && packet_rcv_has_room(pkt_sk(f->arr[i]), skb)) {
+		if (i != idx && packet_rcv_has_room(pkt_sk(f->arr[i]), skb)) {
 			if (i != j)
 				f->next[idx] = i;
 			return i;
 		}
+
 		if (++i == num)
 			i = 0;
 	} while (i != j);
@@ -1386,17 +1390,14 @@ static int packet_rcv_fanout(struct sk_buff *skb, struct net_device *dev,
 		idx = fanout_demux_qm(f, skb, num);
 		break;
 	case PACKET_FANOUT_ROLLOVER:
-		idx = fanout_demux_rollover(f, skb, 0, (unsigned int) -1, num);
+		idx = fanout_demux_rollover(f, skb, 0, false, num);
 		break;
 	}
 
-	po = pkt_sk(f->arr[idx]);
-	if (fanout_has_flag(f, PACKET_FANOUT_FLAG_ROLLOVER) &&
-	    unlikely(!packet_rcv_has_room(po, skb))) {
-		idx = fanout_demux_rollover(f, skb, idx, idx, num);
-		po = pkt_sk(f->arr[idx]);
-	}
+	if (fanout_has_flag(f, PACKET_FANOUT_FLAG_ROLLOVER))
+		idx = fanout_demux_rollover(f, skb, idx, true, num);
 
+	po = pkt_sk(f->arr[idx]);
 	return po->prot_hook.func(skb, dev, &po->prot_hook, orig_dev);
 }
 
-- 
2.2.0.rc0.207.ga3a616c