On Tue, 29 Jul 2025 17:37:24 +0200, Johannes Berg wrote: > On Tue, 2025-07-29 at 23:06 +0800, Tiwei Bie wrote: > > On Mon, 28 Jul 2025 18:27:53 +0200, Johannes Berg wrote: > > > On Tue, 2025-07-29 at 00:04 +0800, Tiwei Bie wrote: > > > > > > +++ b/arch/um/include/asm/spinlock.h > > > > > > @@ -0,0 +1,8 @@ > > > > > > +/* SPDX-License-Identifier: GPL-2.0 */ > > > > > > +#ifndef __ASM_UM_SPINLOCK_H > > > > > > +#define __ASM_UM_SPINLOCK_H > > > > > > + > > > > > > +#include <asm/processor.h> > > > > > > +#include <asm-generic/spinlock.h> > > > > > > + > > > > > > +#endif /* __ASM_UM_SPINLOCK_H */ > > > > > > > > > > Do we need this file? Maybe asm-generic should be including the right > > > > > things it needs? > > > > > > > > I added this file to include asm/processor.h; otherwise, there would be > > > > a lot of compilation errors. Other architectures seem to do the same: > > > > > > > > $ grep -r asm/processor.h arch/ | grep asm/spinlock.h > > > > arch/arm/include/asm/spinlock.h:#include <asm/processor.h> > > > > arch/alpha/include/asm/spinlock.h:#include <asm/processor.h> > > > > arch/arc/include/asm/spinlock.h:#include <asm/processor.h> > > > > arch/hexagon/include/asm/spinlock.h:#include <asm/processor.h> > > > > arch/parisc/include/asm/spinlock.h:#include <asm/processor.h> > > > > arch/x86/include/asm/spinlock.h:#include <asm/processor.h> > > > > arch/s390/include/asm/spinlock.h:#include <asm/processor.h> > > > > arch/mips/include/asm/spinlock.h:#include <asm/processor.h> > > > > arch/loongarch/include/asm/spinlock.h:#include <asm/processor.h> > > > > > > Except for loongarch they all do something else too though. Feels to me > > > um (and loongarch) really shouldn't need that file. > > > > Sorry for the confusion. My point is that since other architectures > > also do this, it seems common practice to include asm/processor.h in > > asm/spinlock.h when necessary. > > Yeah, I understand. > > > > > The reason we need to include asm/processor.h in asm/spinlock.h on UML > > is because: > > > > ticket_spin_lock() (which is an inline function indirectly provided by > > asm-generic/spinlock.h) relies on atomic_cond_read_acquire(), which > > is defined as smp_cond_load_acquire(). > > Right, but that's not the architecture's "fault". > > It seems to me that either spinlock.h should include asm/processor.h for > it,
+1 > or (at least, but I think less appropriate) asm-generic/spinlock.h > should be doing this. > > > On UML, smp_cond_load_acquire() is provided by asm-generic/barrier.h, > > and it relies on smp_cond_load_relaxed(), which is also provided by > > asm-generic/barrier.h on UML. And smp_cond_load_relaxed() is a macro > > that relies on cpu_relax(), which is provided by asm/processor.h. > > In general though, there ought to be some definition of which header > file(s) is/are expected to provide smp_cond_load_acquire() and/or > atomic_cond_read_acquire(). And that header file/those header files > should be included by the files that use the functions/macros. > > > IOW, I think you've stumbled across an inconsistency in the generic > files, and hence we should fix that, rather than having each > architecture paper over it. That does make sense. I will prepare a patch for that. Thanks! Regards, Tiwei
