netdev - [PATCH net] sfc: Fix division by zero when using one RX channel and no SR-IOV

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Date:	Thu, 10 May 2012 03:08:13 +0100
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	David Miller <davem@...emloft.net>
CC:	<netdev@...r.kernel.org>, <linux-net-drivers@...arflare.com>
Subject: [PATCH net] sfc: Fix division by zero when using one RX channel and
 no SR-IOV

If RSS is disabled on the PF (efx->n_rx_channels == 1) we try to set
up the indirection table so that VFs can use it, setting
efx->rss_spread = efx_vf_size(efx).  But if SR-IOV was disabled at
compile time, this evaluates to 0 and we end up dividing by zero when
initialising the table.

I considered changing the fallback definition of efx_vf_size() to
return 1, but its value is really meaningless if we are not going to
enable VFs.  Therefore add a condition of efx_sriov_wanted(efx) in
efx_probe_interrupts().

Signed-off-by: Ben Hutchings <bhutchings@...arflare.com>
---
 drivers/net/ethernet/sfc/efx.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index 3cbfbff..4a00053 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -1349,7 +1349,7 @@ static int efx_probe_interrupts(struct efx_nic *efx)
 	}
 
 	/* RSS might be usable on VFs even if it is disabled on the PF */
-	efx->rss_spread = (efx->n_rx_channels > 1 ?
+	efx->rss_spread = ((efx->n_rx_channels > 1 || !efx_sriov_wanted(efx)) ?
 			   efx->n_rx_channels : efx_vf_size(efx));
 
 	return 0;
-- 
1.7.7.6


-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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