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From: Ziran Zhang <zhangcoder@yeah.net>
To: Gary Guo <gary@garyguo.net>
Cc: Will Deacon <will@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Boqun Feng <boqun@kernel.org>, Thomas Gleixner <tglx@kernel.org>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"H . Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Mark Rutland <mark.rutland@arm.com>,
	linux-kernel@vger.kernel.org, Ziran Zhang <zhangcoder@yeah.net>
Subject: Re: [PATCH] x86/atomic: Add arch_atomic_not()
Date: Wed, 15 Jul 2026 22:30:24 +0800	[thread overview]
Message-ID: <20260715143025.18489-1-zhangcoder@yeah.net> (raw)
In-Reply-To: <DJZ4E9495D1L.1X54VAWGPVYPT@garyguo.net>

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


      reply	other threads:[~2026-07-15 14:32 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-14  5:42 [PATCH] x86/atomic: Add arch_atomic_not() Ziran Zhang
2026-07-15 11:49 ` Gary Guo
2026-07-15 14:30   ` Ziran Zhang [this message]

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