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mlx4: fix potential divide by 0 in mlx4_en_auto_moderation() 

1) In the case where rate == priv->pkt_rate_low == priv->pkt_rate_high,
mlx4_en_auto_moderation() does a divide by zero.

2) We want to properly change the moderation parameters if rx_frames
was changed (like in ethtool -C eth0 rx-frames 16)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2017-02-16 15:23:27 -08:00 committed by David S. Miller
parent 1786dbf370
commit f5a5772337
1 changed files with 14 additions and 10 deletions
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24
drivers/net/ethernet/mellanox/mlx4/en_netdev.c
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@ -1382,6 +1382,7 @@ static void mlx4_en_set_default_moderation(struct mlx4_en_priv *priv)
static void mlx4_en_auto_moderation(struct mlx4_en_priv *priv)
{
unsigned long period = (unsigned long) (jiffies - priv->last_moder_jiffies);
u32 pkt_rate_high, pkt_rate_low;
struct mlx4_en_cq *cq;
unsigned long packets;
unsigned long rate;
@ -1395,37 +1396,40 @@ static void mlx4_en_auto_moderation(struct mlx4_en_priv *priv)
if (!priv->adaptive_rx_coal || period < priv->sample_interval * HZ)
return;
pkt_rate_low = READ_ONCE(priv->pkt_rate_low);
pkt_rate_high = READ_ONCE(priv->pkt_rate_high);
for (ring = 0; ring < priv->rx_ring_num; ring++) {
rx_packets = READ_ONCE(priv->rx_ring[ring]->packets);
rx_bytes = READ_ONCE(priv->rx_ring[ring]->bytes);
rx_pkt_diff = ((unsigned long) (rx_packets -
priv->last_moder_packets[ring]));
rx_pkt_diff = rx_packets - priv->last_moder_packets[ring];
packets = rx_pkt_diff;
rate = packets * HZ / period;
avg_pkt_size = packets ? ((unsigned long) (rx_bytes -
priv->last_moder_bytes[ring])) / packets : 0;
avg_pkt_size = packets ? (rx_bytes -
priv->last_moder_bytes[ring]) / packets : 0;
/* Apply auto-moderation only when packet rate
* exceeds a rate that it matters */
if (rate > (MLX4_EN_RX_RATE_THRESH / priv->rx_ring_num) &&
avg_pkt_size > MLX4_EN_AVG_PKT_SMALL) {
if (rate < priv->pkt_rate_low)
if (rate <= pkt_rate_low)
moder_time = priv->rx_usecs_low;
else if (rate > priv->pkt_rate_high)
else if (rate >= pkt_rate_high)
moder_time = priv->rx_usecs_high;
else
moder_time = (rate - priv->pkt_rate_low) *
moder_time = (rate - pkt_rate_low) *
(priv->rx_usecs_high - priv->rx_usecs_low) /
(priv->pkt_rate_high - priv->pkt_rate_low) +
(pkt_rate_high - pkt_rate_low) +
priv->rx_usecs_low;
} else {
moder_time = priv->rx_usecs_low;
}
if (moder_time != priv->last_moder_time[ring]) {
cq = priv->rx_cq[ring];
if (moder_time != priv->last_moder_time[ring] ||
cq->moder_cnt != priv->rx_frames) {
priv->last_moder_time[ring] = moder_time;
cq = priv->rx_cq[ring];
cq->moder_time = moder_time;
cq->moder_cnt = priv->rx_frames;
err = mlx4_en_set_cq_moder(priv, cq);