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fm10k: avoid divide by zero in rare cases when device is resetting

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It is possible that under rare circumstances the device is undergoing
a reset, such as when a PFLR occurs, and the device may be transmitting
simultaneously. In this case, we might attempt to divide by zero when
finding the proper r_idx. Instead, lets read the num_tx_queues once,
and make sure it's non-zero.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
This commit is contained in:
Jacob Keller 2017-07-10 13:23:11 -07:00 committed by Jeff Kirsher
parent d876c1583b
commit dd5eede2b7
1 changed files with 6 additions and 2 deletions
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8
drivers/net/ethernet/intel/fm10k/fm10k_netdev.c
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@ -643,9 +643,13 @@ int fm10k_close(struct net_device *netdev)
static netdev_tx_t fm10k_xmit_frame(struct sk_buff *skb, struct net_device *dev)
{
struct fm10k_intfc *interface = netdev_priv(dev);
int num_tx_queues = READ_ONCE(interface->num_tx_queues);
unsigned int r_idx = skb->queue_mapping;
int err;
if (!num_tx_queues)
return NETDEV_TX_BUSY;
if ((skb->protocol == htons(ETH_P_8021Q)) &&
!skb_vlan_tag_present(skb)) {
/* FM10K only supports hardware tagging, any tags in frame
@ -698,8 +702,8 @@ static netdev_tx_t fm10k_xmit_frame(struct sk_buff *skb, struct net_device *dev)
__skb_put(skb, pad_len);
}
if (r_idx >= interface->num_tx_queues)
r_idx %= interface->num_tx_queues;
if (r_idx >= num_tx_queues)
r_idx %= num_tx_queues;
err = fm10k_xmit_frame_ring(skb, interface->tx_ring[r_idx]);