linux-kernel - Re: [PATCH] RDMA/irdma: fix irdma_alloc_ucontext

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Message-ID: <CAHYDg1QbNWW=wm4fH71yLVX_gKsPij5jed5R64JbN0mv6Lyx4g@mail.gmail.com>
Date: Tue, 16 Dec 2025 09:17:41 -0500
From: Jacob Moroni <jmoroni@...gle.com>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: Arnd Bergmann <arnd@...nel.org>, Krzysztof Czurylo <krzysztof.czurylo@...el.com>, 
	Tatyana Nikolova <tatyana.e.nikolova@...el.com>, Jason Gunthorpe <jgg@...pe.ca>, 
	Leon Romanovsky <leon@...nel.org>, Faisal Latif <faisal.latif@...el.com>, Arnd Bergmann <arnd@...db.de>, 
	Mustafa Ismail <mustafa.ismail@...el.com>, linux-rdma@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] RDMA/irdma: fix irdma_alloc_ucontext_resp padding

Hi,

This doesn't change the offset of max_hw_srq_quanta on my system, but I tested
with a verbs provider built with the previous and new proposed change
just in case,
and both worked.

Out of curiosity, what is the policy for increasing the size of these
uverbs driver
response structures? I think the response gets silently truncated if the user
provides a smaller buffer, so this shouldn't have broken any user applications
using the old ABI IIUC.

Thanks!

Tested-by: Jacob Moroni <jmoroni@...gle.com>

On Mon, Dec 15, 2025 at 1:43 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>
> Hi Arnd,
>
> On Mon, 8 Dec 2025 at 14:39, Arnd Bergmann <arnd@...nel.org> wrote:
> > From: Arnd Bergmann <arnd@...db.de>
> >
> > A recent modified struct irdma_alloc_ucontext_resp by adding a member
> > with implicit padding in front of it, changing the ABI in an
> > incompatibible way on all architectures other than m68k, as
> > reported by scripts/check-uapi.sh:
> >
> > ==== ABI differences detected in include/rdma/irdma-abi.h from 1dd7bde2e91c -> HEAD ====
> >     [C] 'struct irdma_alloc_ucontext_resp' changed:
> >       type size changed from 704 to 640 (in bits)
> >       1 data member deletion:
> >         '__u8 rsvd3[2]', at offset 640 (in bits) at irdma-abi.h:61:1
> >       1 data member insertion:
> >         '__u8 revd3[2]', at offset 592 (in bits) at irdma-abi.h:60:1
> >
> > Change the ABI back to the previous version, by moving the new
> > max_hw_srq_quanta member into a naturally aligned location.
> >
> > Fixes: 563e1feb5f6e ("RDMA/irdma: Add SRQ support")
> > Signed-off-by: Arnd Bergmann <arnd@...db.de>
>
> Thanks for the discussion in Tokyo!
>
> Reviewed-by: Geert Uytterhoeven <geert@...ux-m68k.org>
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
>