Re: linux-next: build failure after merge of the vfs-brauner tree

[Jori Koolstra]

> Op 03-06-2026 16:13 CEST schreef Aleksa Sarai <cyphar@xxxxxxxxxx>:
> 
>  
> On 2026-06-03, Jori Koolstra <jkoolstra@xxxxxxxxx> wrote:
> > 
> > > Op 27-05-2026 15:09 CEST schreef Aleksa Sarai <aleksa@xxxxxxxxxxxx>:
> > > 
> > > If we could also get some comments in asm-generic that tell you which
> > > flag bits are "cursed", that would also be quite great. My impression is
> > > a fair number of people forget to check the arch-specific headers, so
> > > having a note in the generic one would let us avoid this issue in future
> > > (and IMHO will be more effective than just switching from octal).
> > > 
> > 
> > Just to be sure, what do you mean by cursed here? Maybe just a reminder that
> > there are arch-specific O_ flags? A list of all of them that may have an
> > arch specific redefinition is basically all of them...
> 
> I was mainly thinking of the ones that appear free but actually aren't
> -- so these are the ones where there are only arch-specific flags that
> take them.
> 
> Basically, I would prefer the list in the asm-generic header be
> something like:
> 
>  #define O_FOO 0x001
>  #define O_BAR 0x002
>  /* 0x004 must not be used -- it conflicts with flags on alpha and s390. */
>  #define O_BAZ 0x010
>  /* 0x020 must not be used -- it conflicts with flags on parisc. */
> 
> The fact that some flags have their order mixed up on different
> architectures is funny trivia but when allocating a new flag, the thing
> that trips most people up is that it looks like a flag is free in
> asm-generic but some architecture is using that flag and you'll only
> find out when someone compile-tests for that other architecture.
> 
> Depending on how many O_* flag bits we have, this might even allow us to
> enforce non-arch-specific O_* flags (like we did for syscall numbers a
> few years ago).
> 

Okay, that makes sense. But you can reuse those bits in asm-generic if you just
redefine the new O_ flag in the conflicting arch-specific fcntls, right? Maybe
we don't want that, but that leaves fewer bits in the O_ space.

> -- 
> Aleksa Sarai
> Founding Engineer at Amutable
> https://www.cyphar.com/