From 09c1c68f2239dcd99b76be2c44e84811fba273db Mon Sep 17 00:00:00 2001 From: Sathya Perla Date: Mon, 22 Aug 2011 19:41:53 +0000 Subject: [PATCH] be2net: fix erx->rx_drops_no_frags wrap around 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 Signed-off-by: David S. Miller --- drivers/net/ethernet/emulex/benet/be_main.c | 22 +++++++++++++++++++--- 1 file 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, -- 2.7.4