diff options
| -rw-r--r-- | net/packet/af_packet.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 82a50e850245..53c1d41fb1c9 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1295,15 +1295,21 @@ static void packet_sock_destruct(struct sock *sk) static bool fanout_flow_is_huge(struct packet_sock *po, struct sk_buff *skb) { - u32 rxhash; + u32 *history = po->rollover->history; + u32 victim, rxhash; int i, count = 0; rxhash = skb_get_hash(skb); for (i = 0; i < ROLLOVER_HLEN; i++) - if (po->rollover->history[i] == rxhash) + if (READ_ONCE(history[i]) == rxhash) count++; - po->rollover->history[prandom_u32() % ROLLOVER_HLEN] = rxhash; + victim = prandom_u32() % ROLLOVER_HLEN; + + /* Avoid dirtying the cache line if possible */ + if (READ_ONCE(history[victim]) != rxhash) + WRITE_ONCE(history[victim], rxhash); + return count > (ROLLOVER_HLEN >> 1); } |