[PATCH net-next 3/5] be2net: fix erx->rx_drops_no_frags wrap around
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STALE5535d
From: Sathya Perla <hidden>
Date: 2011-08-23 05:42:51
Subsystem:
emulex 10gbps nic be2, be3-r, lancer, skyhawk-r driver (be2net), networking drivers, the rest · Maintainers:
Ajit Khaparde, Sriharsha Basavapatna, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
The rx_drops_no_frags HW counter for RSS rings is 16bits in HW and can wraparound often. Maintain a 32-bit accumulator in the driver to prevent frequent wraparound. Also, incorporated Eric's feedback to use ACCESS_ONCE() for the accumulator write. Signed-off-by: Sathya Perla <redacted> --- drivers/net/ethernet/emulex/benet/be_main.c | 22 +++++++++++++++++++--- 1 files changed, 19 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/emulex/benet/be_main.c b/drivers/net/ethernet/emulex/benet/be_main.c
index 2375c0c..fb2eda0 100644
--- a/drivers/net/ethernet/emulex/benet/be_main.c
+++ b/drivers/net/ethernet/emulex/benet/be_main.c@@ -378,6 +378,18 @@ static void populate_lancer_stats(struct be_adapter *adapter) pport_stats->rx_drops_too_many_frags_lo; } +static void accumulate_16bit_val(u32 *acc, u16 val) +{ +#define lo(x) (x & 0xFFFF) +#define hi(x) (x & 0xFFFF0000) + bool wrapped = val < lo(*acc); + u32 newacc = hi(*acc) + val; + + if (wrapped) + newacc += 65536; + ACCESS_ONCE(*acc) = newacc; +} + void be_parse_stats(struct be_adapter *adapter) { struct be_erx_stats_v1 *erx = be_erx_stats_from_cmd(adapter);
@@ -394,9 +406,13 @@ void be_parse_stats(struct be_adapter *adapter) } /* as erx_v1 is longer than v0, ok to use v1 defn for v0 access */ - for_all_rx_queues(adapter, rxo, i) - rx_stats(rxo)->rx_drops_no_frags = - erx->rx_drops_no_fragments[rxo->q.id]; + for_all_rx_queues(adapter, rxo, i) { + /* below erx HW counter can actually wrap around after + * 65535. Driver accumulates a 32-bit value + */ + accumulate_16bit_val(&rx_stats(rxo)->rx_drops_no_frags, + (u16)erx->rx_drops_no_fragments[rxo->q.id]); + } } static struct rtnl_link_stats64 *be_get_stats64(struct net_device *netdev,
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1.7.4