Re: [tip: perf/core] perf/x86: Annotate struct bts_buffer with __counted_by()

[Thorsten Blum <thorsten.blum@linux.dev>]

On 5. Mar 2025, at 10:18, Ingo Molnar wrote:
> Actually, on a second thought:
> 
>> - buf = kzalloc_node(offsetof(struct bts_buffer, buf[nbuf]), GFP_KERNEL, node);
>> + buf = kzalloc_node(struct_size(buf, buf, nbuf), GFP_KERNEL, node);
> 
> Firstly, in what world is 'buf, buf' more readable? One is a member of 
> a structure, the other is the name of the structure - and they match, 
> which shows that this function's naming conventions are a mess.
> 
> Which should be fixed first ...

Yes, I noticed this too, but since buf->buf[] is used all over the place
(also in other functions), I didn't rename it in this patch.

We could just keep offsetof(struct bts_buffer, buf[nbuf]), or use
struct_size_t(struct bts_buffer, buf, nbuf) and still benefit from
additional compile-time checks, or rename the local variable to struct
bts_buffer *bts and use struct_size(bts, buf, nbuf), for example. Any
preferences or other ideas?

> I'm also not sure the code is correct ...

Which part of it?

Thanks,
Thorsten