Re: [PATCH] vmxnet3: fix LRO feature check

The 03/20/2018 10:57, David Miller wrote:

From: kbuild test robot <redacted>
Date: Sun, 18 Mar 2018 14:37:35 +0800

quoted

All warnings (new ones prefixed by >>):

   drivers/net/vmxnet3/vmxnet3_drv.c: In function 'vmxnet3_rq_rx_complete':

quoted

quoted

drivers/net/vmxnet3/vmxnet3_drv.c:1474:8: warning: suggest parentheses around operand of '!' or change '&' to '&&' or '!' to '~' [-Wparentheses]

           !adapter->netdev->features & NETIF_F_LRO) {
           ^~~~~~~~~~~~~~~~~~~~~~~~~~

Igor, I will fix this up for you.  But it is clear that this patch wasn't tested
very well.

Because !adapter->netdev->features evaluates wholly before the "& NETIF_F_LRO",
the flags aren't being tested properly at all.

My bad.

I have even been looking at C operator precedence table:

----------------------------
| Operator | Associativity |
|--------------------------|
| ++ --    | right-to-left |
| + -      |               |
| ! ~      |               |
| (type)   |               |
| *        |               |
| &        |               |
| sizeof   |               |
----------------------------

According to this table '&' will be evaluated first, because it is on the right side.

But yeah, that was "Address of", not "Bitwise AND".