diff options
| author | Sathya Perla <sathya.perla@emulex.com> | 2011-08-22 19:41:53 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2011-08-24 16:19:29 -0700 |
| commit | 09c1c68f2239dcd99b76be2c44e84811fba273db (patch) | |
| tree | bbbede1f08fb5663a39528deabae91a20cef8969 /drivers/net/ethernet/emulex | |
| parent | db3ea7819d035ff01c8260fce364511adfae0eaa (diff) | |
| download | lwn-09c1c68f2239dcd99b76be2c44e84811fba273db.tar.gz lwn-09c1c68f2239dcd99b76be2c44e84811fba273db.zip | |
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 <sathya.perla@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet/emulex')
| -rw-r--r-- | 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 2375c0c3d1b3..fb2eda08a094 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, |