Re: [PATCH v4 13/13] riscv: Add qspinlock support

Andrew Jones
2024-08-01T10:15:16Z

On Thu, Aug 01, 2024 at 10:43:03AM GMT, Alexandre Ghiti wrote:
...
> > > diff --git a/include/asm-generic/qspinlock.h b/include/asm-generic/qspinlock.h
> > > index 0655aa5b57b2..bf47cca2c375 100644
> > > --- a/include/asm-generic/qspinlock.h
> > > +++ b/include/asm-generic/qspinlock.h
> > > @@ -136,6 +136,7 @@ static __always_inline bool virt_spin_lock(struct qspinlock *lock)
> > > }
> > > #endif
> > >
> > > +#ifndef __no_arch_spinlock_redefine
> >
> > I'm not sure what's better/worse, but instead of inventing this
> > __no_arch_spinlock_redefine thing we could just name all the functions
> > something like __arch_spin* and then add defines for both to asm/spinlock.h,
> > i.e.
> >
> > #define queued_spin_lock(l) __arch_spin_lock(l)
> > ...
> >
> > #define ticket_spin_lock(l) __arch_spin_lock(l)
> > ...
>
> __arch_spin_lock() would use queued_spin_lock() so that would make an
> "infinite recursive definition" right? And that would override the
> "real" queued_spin_lock() implementation too.
>
> But maybe I missed something!
>

It depends on where the definition is done. It should work if the
preprocessor expands the implementation of __arch_spin_* before
evaluating the #define of queued_spin_*. IOW, we just need to put
the defines after the static inline constructions.

Thanks,
drew