| Message ID | 20170710202319.22110-8-jacob.e.keller@intel.com |
|---|---|
| State | Accepted |
| Delegated to: | Jeff Kirsher |
| Headers | show |
> -----Original Message----- > From: Intel-wired-lan [mailto:intel-wired-lan-bounces@osuosl.org] On Behalf > Of Jacob Keller > Sent: Monday, July 10, 2017 1:23 PM > To: jtkirhse@osuosl.org; Intel Wired LAN <intel-wired-lan@lists.osuosl.org> > Cc: jekeller@osuosl.org > Subject: [Intel-wired-lan] [PATCH v3 08/16] fm10k: avoid divide by zero in rare > cases when device is resetting > > 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>
diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_netdev.c b/drivers/net/ethernet/intel/fm10k/fm10k_netdev.c index 5e37387c7082..1154a920f127 100644 --- a/drivers/net/ethernet/intel/fm10k/fm10k_netdev.c +++ b/drivers/net/ethernet/intel/fm10k/fm10k_netdev.c @@ -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]);
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> --- drivers/net/ethernet/intel/fm10k/fm10k_netdev.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)