Re: [PATCH] alloc_tag: remove empty module tag section

[Suren Baghdasaryan]

On Tue, Jun 17, 2025 at 2:27 AM Petr Pavlu <petr.pavlu@xxxxxxxx> wrote:
>
> On 6/10/25 6:22 PM, Casey Chen wrote:
> > The empty MOD_CODETAG_SECTIONS() macro added an incomplete .data
> > section in module linker script, which caused symbol lookup tools
> > like gdb to misinterpret symbol addresses e.g., __ib_process_cq
> > incorrectly mapping to unrelated functions like below.
> >
> >   (gdb) disas __ib_process_cq
> >   Dump of assembler code for function trace_event_fields_cq_schedule:
> >
> > Removing the empty section restores proper symbol resolution and
> > layout, ensuring .data placement behaves as expected.
>
> The patch looks ok me, but I'm somewhat confused about the problem.
> I think a linker should not add an empty output section if it doesn't
> contain anything, or if .data actually contains something then the extra
> dummy definition should be also harmless?

I also assumed so but apparently this is not entirely harmless.

>
> This also reminds me of my previous related fix "codetag: Avoid unused
> alloc_tags sections/symbols" [1] which fell through the cracks. I can
> rebase it on top of this patch.
>
> [1] https://lore.kernel.org/all/20250313143002.9118-1-petr.pavlu@xxxxxxxx/

Yes please.

>
> --
> Thanks,
> Petr