netdev - [net-intel-i40e] question about assignment overwrite

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Date:   Wed, 17 May 2017 15:48:58 -0500
From:   "Gustavo A. R. Silva" <garsilva@...eddedor.com>
To:     Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Cc:     intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [net-intel-i40e] question about assignment overwrite


Hello everybody,

While looking into Coverity ID 1408956 I ran into the following piece  
of code at drivers/net/ethernet/intel/i40e/i40e_main.c:8807:

8807        if (pf->hw.mac.type == I40E_MAC_X722) {
8808                pf->flags |= I40E_FLAG_RSS_AQ_CAPABLE
8809                             | I40E_FLAG_128_QP_RSS_CAPABLE
8810                             | I40E_FLAG_HW_ATR_EVICT_CAPABLE
8811                             | I40E_FLAG_OUTER_UDP_CSUM_CAPABLE
8812                             | I40E_FLAG_WB_ON_ITR_CAPABLE
8813                             | I40E_FLAG_MULTIPLE_TCP_UDP_RSS_PCTYPE
8814                             | I40E_FLAG_NO_PCI_LINK_CHECK
8815                             | I40E_FLAG_USE_SET_LLDP_MIB
8816                             | I40E_FLAG_GENEVE_OFFLOAD_CAPABLE
8817                             | I40E_FLAG_PTP_L4_CAPABLE
8818                             | I40E_FLAG_WOL_MC_MAGIC_PKT_WAKE;
8819        } else if ((pf->hw.aq.api_maj_ver > 1) ||
8820                   ((pf->hw.aq.api_maj_ver == 1) &&
8821                    (pf->hw.aq.api_min_ver > 4))) {
8822                /* Supported in FW API version higher than 1.4 */
8823                pf->flags |= I40E_FLAG_GENEVE_OFFLOAD_CAPABLE;
8824                pf->flags = I40E_FLAG_HW_ATR_EVICT_CAPABLE;
8825        } else {
8826                pf->flags = I40E_FLAG_HW_ATR_EVICT_CAPABLE;
8827        }

The issue here is that the assignment at line 8823 is overwritten by  
the code at line 8824.

I'm suspicious that line 8824 should be remove and a patch like the  
following can be applied:

index d5c9c9e..48ffa73 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -8821,7 +8821,6 @@ static int i40e_sw_init(struct i40e_pf *pf)
                     (pf->hw.aq.api_min_ver > 4))) {
                 /* Supported in FW API version higher than 1.4 */
                 pf->flags |= I40E_FLAG_GENEVE_OFFLOAD_CAPABLE;
-               pf->flags = I40E_FLAG_HW_ATR_EVICT_CAPABLE;
         } else {
                 pf->flags = I40E_FLAG_HW_ATR_EVICT_CAPABLE;
         }

What do you think?

Thanks!
--
Gustavo A. R. Silva