Re: [net-intel-i40e] question about assignment overwrite

[Jeff Kirsher]

On Wed, 2017-06-07 at 16:55 -0300, Mauro Rodrigues wrote:
> On Wed, May 17, 2017 at 10:49:11PM -0700, Jeff Kirsher wrote:
> > On Wed, 2017-05-17 at 15:48 -0500, Gustavo A. R. Silva wrote:
> > > While looking into Coverity ID 1408956 I ran into the following
> > > pieceÂÂ
> > > of code at drivers/net/ethernet/intel/i40e/i40e_main.c:8807:
> > > 
> > > 8807ÂÂÂÂÂÂÂ if (pf->hw.mac.type == I40E_MAC_X722) {
> > > 8808ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ pf->flags |= I40E_FLAG_RSS_AQ_CAPABLE
> > > 8809ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ | I40E_FLAG_128_QP_RSS_CAPABLE
> > > 8810ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ | I40E_FLAG_HW_ATR_EVICT_CAPABLE
> > > 8811ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ | I40E_FLAG_OUTER_UDP_CSUM_CAPABLE
> > > 8812ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ | I40E_FLAG_WB_ON_ITR_CAPABLE
> > > 8813ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ |
> > > I40E_FLAG_MULTIPLE_TCP_UDP_RSS_PCTYPE
> > > 8814ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ | I40E_FLAG_NO_PCI_LINK_CHECK
> > > 8815ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ | I40E_FLAG_USE_SET_LLDP_MIB
> > > 8816ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ | I40E_FLAG_GENEVE_OFFLOAD_CAPABLE
> > > 8817ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ | I40E_FLAG_PTP_L4_CAPABLE
> > > 8818ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ | I40E_FLAG_WOL_MC_MAGIC_PKT_WAKE;
> > > 8819ÂÂÂÂÂÂÂ } else if ((pf->hw.aq.api_maj_ver > 1) ||
> > > 8820ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ ((pf->hw.aq.api_maj_ver == 1) &&
> > > 8821ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ (pf->hw.aq.api_min_ver > 4))) {
> > > 8822ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ /* Supported in FW API version higher than 1.4 */
> > > 8823ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ pf->flags |= I40E_FLAG_GENEVE_OFFLOAD_CAPABLE;
> > > 8824ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ pf->flags = I40E_FLAG_HW_ATR_EVICT_CAPABLE;
> > > 8825ÂÂÂÂÂÂÂ } else {
> > > 8826ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ pf->flags = I40E_FLAG_HW_ATR_EVICT_CAPABLE;
> > > 8827ÂÂÂÂÂÂÂ }
> > > 
> > > The issue here is that the assignment at line 8823 is overwritten
> > > byÂÂ
> > > the code at line 8824.
> > > 
> > > I'm suspicious that line 8824 should be remove and a patch like theÂÂ
> > > 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)
> > > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ (pf->hw.aq.api_min_ver > 4))) {
> > > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ /* Supported in FW API version higher than 1.4 */
> > > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ pf->flags |= I40E_FLAG_GENEVE_OFFLOAD_CAPABLE;
> > > -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ pf->flags = I40E_FLAG_HW_ATR_EVICT_CAPABLE;
> > > ÂÂÂÂÂÂÂÂ } else {
> > > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ pf->flags = I40E_FLAG_HW_ATR_EVICT_CAPABLE;
> > > ÂÂÂÂÂÂÂÂ }
> > > 
> > > What do you think?
> > 
> > This issue is already fixed in my dev-queue branch on my next-queue
> > tree.
> 
> Hi Jeff, are you planning to push this fix into net branch anytime soon?
> 
> Thanks,
> 
> Mauro

The patch that fixed this issue is already in David Miller's net-next tree.

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