Re: [PATCH] RDMA/hfi1: use a struct group to avoid warning

[Leon Romanovsky]

On Tue, Apr 08, 2025 at 02:40:38PM +0200, Arnd Bergmann wrote:
> On Mon, Apr 7, 2025, at 20:27, Jason Gunthorpe wrote:
> > On Thu, Apr 03, 2025 at 04:47:53PM +0200, Arnd Bergmann wrote:
> >> From: Arnd Bergmann <arnd@xxxxxxxx>
> >> 
> >> On gcc-11 and earlier, the driver sometimes produces a warning
> >> for memset:
> >> 
> >> In file included from include/linux/string.h:392,
> >>                  from drivers/infiniband/hw/hfi1/mad.c:6:
> >> In function 'fortify_memset_chk',
> >>     inlined from '__subn_get_opa_hfi1_cong_log' at drivers/infiniband/hw/hfi1/mad.c:3873:2,
> >>     inlined from 'subn_get_opa_sma' at drivers/infiniband/hw/hfi1/mad.c:4114:9:
> >> include/linux/fortify-string.h:480:4: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror]
> >>     __write_overflow_field(p_size_field, size);
> >>     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >> 
> >> This seems to be a false positive, and I found no nice way to rewrite
> >> the code to avoid the warning, but adding a a struct group works.
> >
> > Er.. so do we really want to fix it or just ignore this on gcc-11? Or
> > is there really a compile bug here and it is mis-generating the code?
> >
> > The unneeded struct group seems ugly to me?
> 
> Having a clean build would be nice though. Do you think a patch
> that just turns off the warning locally would be better?

I don't think so, as you will need to disable warning for specific
compiler, which won't be nice.

My preference is to have a fix.

Thanks

> 
>       Arnd