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Commit f5a57723 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

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: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarSaeed Mahameed <saeedm@mellanox.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1786dbf3

drivers/net/ethernet/mellanox/mlx4/en_netdev.c

+14 −10
Original line number Diff line number Diff line
@@ -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]) {

			priv->last_moder_time[ring] = moder_time;

		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->moder_time = moder_time;

			cq->moder_cnt = priv->rx_frames;

			err = mlx4_en_set_cq_moder(priv, cq);