netdev - [PATCH net-next v2 05/10] bnxt_en: Fix ethtool -l|-L inconsistent channel counts.

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Date:   Tue, 20 Sep 2016 02:50:23 -0400
From:   Michael Chan <michael.chan@...adcom.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org
Subject: [PATCH net-next v2 05/10] bnxt_en: Fix ethtool -l|-L inconsistent channel counts.

The existing code is inconsistent in reporting and accepting the combined
channel count.  bnxt_get_channels() reports maximum combined as the
maximum rx count.  bnxt_set_channels() accepts combined count that
cannot be bigger than max rx or max tx.

For example, if max rx = 2 and max tx = 1, we report max supported
combined to be 2.  But if the user tries to set combined to 2, it will
fail because 2 is bigger than max tx which is 1.

Fix the code to be consistent.  Max allowed combined = max(max_rx, max_tx).
We will accept a combined channel count <= max(max_rx, max_tx).

Signed-off-by: Michael Chan <michael.chan@...adcom.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
index ae4458d..de893c9 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
@@ -348,7 +348,7 @@ static void bnxt_get_channels(struct net_device *dev,
 	int max_rx_rings, max_tx_rings, tcs;

 	bnxt_get_max_rings(bp, &max_rx_rings, &max_tx_rings, true);
-	channel->max_combined = max_rx_rings;
+	channel->max_combined = max_t(int, max_rx_rings, max_tx_rings);

 	if (bnxt_get_max_rings(bp, &max_rx_rings, &max_tx_rings, false)) {
 		max_rx_rings = 0;
@@ -406,8 +406,8 @@ static int bnxt_set_channels(struct net_device *dev,
 	if (tcs > 1)
 		max_tx_rings /= tcs;

-	if (sh && (channel->combined_count > max_rx_rings ||
-		   channel->combined_count > max_tx_rings))
+	if (sh &&
+	    channel->combined_count > max_t(int, max_rx_rings, max_tx_rings))
 		return -ENOMEM;

 	if (!sh && (channel->rx_count > max_rx_rings ||
@@ -430,8 +430,10 @@ static int bnxt_set_channels(struct net_device *dev,

 	if (sh) {
 		bp->flags |= BNXT_FLAG_SHARED_RINGS;
-		bp->rx_nr_rings = channel->combined_count;
-		bp->tx_nr_rings_per_tc = channel->combined_count;
+		bp->rx_nr_rings = min_t(int, channel->combined_count,
+					max_rx_rings);
+		bp->tx_nr_rings_per_tc = min_t(int, channel->combined_count,
+					       max_tx_rings);
 	} else {
 		bp->flags &= ~BNXT_FLAG_SHARED_RINGS;
 		bp->rx_nr_rings = channel->rx_count;
-- 
1.8.3.1