Subject: Re: [PATCH v4 net-next 12/12] mlx5: support BIG TCP packets

From: Jakub Kicinski <[email-masked]>
Date: Fri, 6 May 2022 15:34:14 -0700

On Fri,  6 May 2022 08:30:48 -0700 Eric Dumazet wrote:
> From: Coco Li <[email-masked]>
> 
> mlx5 supports LSOv2.
> 
> IPv6 gro/tcp stacks insert a temporary Hop-by-Hop header
> with JUMBO TLV for big packets.
> 
> We need to ignore/skip this HBH header when populating TX descriptor.
> 
> Note that ipv6_has_hopopt_jumbo() only recognizes very specific packet
> layout, thus mlx5e_sq_xmit_wqe() is taking care of this layout only.
> 
> v2: clear hopbyhop in mlx5e_tx_get_gso_ihs()
> v4: fix compile error for CONFIG_MLX5_CORE_IPOIB=y

In file included from ../include/linux/string.h:253,
                 from ../arch/x86/include/asm/page_32.h:22,
                 from ../arch/x86/include/asm/page.h:14,
                 from ../arch/x86/include/asm/processor.h:19,
                 from ../arch/x86/include/asm/timex.h:5,
                 from ../include/linux/timex.h:65,
                 from ../include/linux/time32.h:13,
                 from ../include/linux/time.h:60,
                 from ../include/linux/skbuff.h:15,
                 from ../include/linux/tcp.h:17,
                 from ../drivers/net/ethernet/mellanox/mlx5/core/en_tx.c:33:
In function ‘fortify_memcpy_chk’,
    inlined from ‘mlx5e_insert_vlan’ at ../drivers/net/ethernet/mellanox/mlx5/core/en_tx.c:104:2,
    inlined from ‘mlx5e_sq_xmit_wqe’ at ../drivers/net/ethernet/mellanox/mlx5/core/en_tx.c:404:5:
../include/linux/fortify-string.h:328:25: warning: call to ‘__write_overflow_field’ declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning]
  328 |                         __write_overflow_field(p_size_field, size);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘fortify_memcpy_chk’,
    inlined from ‘mlx5e_sq_xmit_wqe’ at ../drivers/net/ethernet/mellanox/mlx5/core/en_tx.c:408:5:
../include/linux/fortify-string.h:328:25: warning: call to ‘__write_overflow_field’ declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning]
  328 |                         __write_overflow_field(p_size_field, size);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘fortify_memcpy_chk’,
    inlined from ‘mlx5i_sq_xmit’ at ../drivers/net/ethernet/mellanox/mlx5/core/en_tx.c:962:4:
../include/linux/fortify-string.h:328:25: warning: call to ‘__write_overflow_field’ declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning]
  328 |                         __write_overflow_field(p_size_field, size);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~