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be2net: fix erx->rx_drops_no_frags wrap around

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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>
This commit is contained in:
Sathya Perla 2011-08-22 19:41:53 +00:00 committed by David S. Miller
parent db3ea7819d
commit 09c1c68f22
1 changed files with 19 additions and 3 deletions
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22
drivers/net/ethernet/emulex/benet/be_main.c
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@ -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,