On Thu, Feb 27, 2025, at 14:49, Pavel Begunkov wrote:
> On 2/27/25 13:20, Arnd Bergmann wrote:
>> | ^~~
>>
>> Since io_is_compat() turns into a compile-time 'false', the #ifdef
>> here is completely unnecessary, and removing it avoids the warning.
>
> I don't think __get_compat_msghdr() and other helpers are
> compiled for !COMPAT.
They are not defined without CONFIG_COMPAT. My point in the
message is that io_is_compat() turning into a compile-time
'false' value means that they also don't get called, because
compilers are really good at this type of dead code elimination.
> I'd just silence it like:
>
> if (io_is_compat(req->ctx)) {
> ret = -EFAULT;
> #ifdef CONFIG_COMPAT
> ...
> #endif CONFIG_COMPAT
> }
That seems even less readable. If you want to be explicit
about it, you could use
if (IS_ENABLED(CONFIG_COMPAT) && io_is_compat(req->ctx)) {
to replace the #ifdef, but as I wrote in the patch
description, the compile-time check is really redundant
because io_is_compat() is meant to do exactly that.
Arnd
