Re: [PATCH] RDMA/siw: Trim size of page array to max size needed

[Guoqing Jiang <guoqing.jiang@linux.dev>]

Hi Bernard,

On 1/19/24 21:05, Bernard Metzler wrote:
> siw tries sending all parts of an iWarp wire frame in one socket
> send operation. If user data can be send without copy, user data
> pages for one wire frame are referenced in an fixed size page array.
> The size of this array can be made 2 elements smaller, since it
> does not reference iWarp header and trailer crc. Trimming
> the page array reduces the affected siw_tx_hdt() functions frame
> size, staying below 1024 bytes. This avoids the following
> compile-time warning:
>
>   drivers/infiniband/sw/siw/siw_qp_tx.c: In function 'siw_tx_hdt':
>   drivers/infiniband/sw/siw/siw_qp_tx.c:677:1: warning: the frame
>   size of 1040 bytes is larger than 1024 bytes [-Wframe-larger-than=]

I saw similar warning in my ubuntu 22.04 VM which has below gcc.

root@buk:/home/gjiang/linux-mirror# make M=drivers/infiniband/sw/siw/ 
-j16 W=1
   CC [M]  drivers/infiniband/sw/siw/siw_qp_tx.o
drivers/infiniband/sw/siw/siw_qp_tx.c: In function ‘siw_tx_hdt’:
drivers/infiniband/sw/siw/siw_qp_tx.c:665:1: warning: the frame size of 
1440 bytes is larger than 1024 bytes [-Wframe-larger-than=]
   665 | }
       | ^

# gcc --version
gcc (Ubuntu 12.3.0-1ubuntu1~22.04) 12.3.0

And it still appears after apply this patch on top of 6.8-rc1.

root@buk:/home/gjiang/linux-mirror# git am 
./20240119_bmt_rdma_siw_trim_size_of_page_array_to_max_size_needed.mbx
Applying: RDMA/siw: Trim size of page array to max size needed
root@buk:/home/gjiang/linux-mirror# make M=drivers/infiniband/sw/siw/ 
-j16 W=1
   CC [M]  drivers/infiniband/sw/siw/siw_qp_tx.o
drivers/infiniband/sw/siw/siw_qp_tx.c: In function ‘siw_tx_hdt’:
drivers/infiniband/sw/siw/siw_qp_tx.c:668:1: warning: the frame size of 
1408 bytes is larger than 1024 bytes [-Wframe-larger-than=]
   668 | }
       | ^

However with gcc-13.1, I can't see the warning with or without the patch.

Thanks,
Guoqing