On Wed, 2012-06-06 at 14:13 +0300, Michael S. Tsirkin wrote:
> We currently do all stats either on napi callback or from
> start_xmit callback.
> This makes them safe, yes?
Hmm, then _bh() variant is needed in virtnet_stats(), as explained in
include/linux/u64_stats_sync.h section 6)
* 6) If counter might be written by an interrupt, readers should block interrupts.
* (On UP, there is no seqcount_t protection, a reader allowing interrupts could
* read partial values)
Yes, its tricky...
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 5214b1e..705aaa7 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -703,12 +703,12 @@ static struct rtnl_link_stats64 *virtnet_stats(struct net_device *dev,
u64 tpackets, tbytes, rpackets, rbytes;
do {
- start = u64_stats_fetch_begin(&stats->syncp);
+ start = u64_stats_fetch_begin_bh(&stats->syncp);
tpackets = stats->tx_packets;
tbytes = stats->tx_bytes;
rpackets = stats->rx_packets;
rbytes = stats->rx_bytes;
- } while (u64_stats_fetch_retry(&stats->syncp, start));
+ } while (u64_stats_fetch_retry_bh(&stats->syncp, start));
tot->rx_packets += rpackets;
tot->tx_packets += tpackets;
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