[PATCH net] bnx2x: Fix Multi-Cos

[PATCH net] bnx2x: Fix Multi-Cos

[Yuval Mintz]

Apparently multi-cos isn't working for bnx2x quite some time -
driver implements ndo_select_queue() to allow queue-selection
for FCoE, but the regular L2 flow would cause it to modulo the
fallback's result by the number of queues.
The fallback would return a queue matching the needed tc
[via __skb_tx_hash()], but since the modulo is by the number of TSS
queues where number of TCs is not accounted, transmission would always
be done by a queue configured into using TC0.

Fixes: ada7c19e6d27 ("bnx2x: use XPS if possible for bnx2x_select_queue instead of pure hash")
Signed-off-by: Yuval Mintz <Yuval.Mintz@cavium.com>
---
Hi Dave,

Please consider applying this to `net'.

Thanks,
Yuval
---
 drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
index eccb3d1..5f49334 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
@@ -1926,7 +1926,7 @@ u16 bnx2x_select_queue(struct net_device *dev, struct sk_buff *skb,
 	}
 
 	/* select a non-FCoE queue */
-	return fallback(dev, skb) % BNX2X_NUM_ETH_QUEUES(bp);
+	return fallback(dev, skb) % (BNX2X_NUM_ETH_QUEUES(bp) * bp->max_cos);
 }
 
 void bnx2x_set_num_queues(struct bnx2x *bp)
-- 
2.7.4

Re: [PATCH net] bnx2x: Fix Multi-Cos

[David Miller]

From: Yuval Mintz <Yuval.Mintz@cavium.com>
Date: Thu, 1 Jun 2017 15:57:56 +0300

> Apparently multi-cos isn't working for bnx2x quite some time -
> driver implements ndo_select_queue() to allow queue-selection
> for FCoE, but the regular L2 flow would cause it to modulo the
> fallback's result by the number of queues.
> The fallback would return a queue matching the needed tc
> [via __skb_tx_hash()], but since the modulo is by the number of TSS
> queues where number of TCs is not accounted, transmission would always
> be done by a queue configured into using TC0.
> 
> Fixes: ada7c19e6d27 ("bnx2x: use XPS if possible for bnx2x_select_queue instead of pure hash")
> Signed-off-by: Yuval Mintz <Yuval.Mintz@cavium.com>

Applied and queued up for -stable.