Re: [PATCH] x86/atomic: Add arch_atomic_not()

[Ziran Zhang]

On Wed, 15 Jul 2026 12:49:20 +0100, Gary Guo wrote:
> > The kernel already has non-atomic bitmap_complement(), but
> > no direct atomic implementation.
> >
> > According to Intel and AMD manuals, the NOT instruction
> > supports a LOCK prefix.
> >
> > Currently the only way to achieve this is arch_atomic_xor(-1, v),
> > which is non-obvious and hurts readability, so add arch_atomic_not()
> > to provide an explicit atomic complement operation.
> 
> What do you need this for?
> 
> Best,
> Gary

Hi Gary,

At present there is no code in kernel that would call
arch_atomic_not() or arch_atomic_xor(~0,v).
I'll drop this patch and revisit if a real use case 
shows up in the future.

Thanks for the review!

Regards,
Ziran Zhang