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Diffstat (limited to 'net/packet/af_packet.c')
-rw-r--r--net/packet/af_packet.c12
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);
}