Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 27 Feb 2019 18:34:22 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        Andrew Lutomirski <luto@kernel.org>,
        Nadav Amit <namit@vmware.com>,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        Nadav Amit <nadav.amit@gmail.com>
Subject: Re: [PATCH 1/5] x86/percpu: Differentiate this_cpu_{}() and
 __this_cpu_{}()
Message-ID: <20190227173422.GV32494@hirez.programming.kicks-ass.net>
References: <20190227101252.413192716@infradead.org>
 <20190227101544.210748832@infradead.org>
 <CAHk-=wiv6dgJDj81wukpJCJBVhAVn-CYJdhj+o8JGN1LfRwb0g@mail.gmail.com>
 <20190227164806.GS32494@hirez.programming.kicks-ass.net>
 <CAHk-=wi_0GUBgi3guWqUzT3gZOAC+iEyZcSLdw0=_9xWJEwHZg@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAHk-=wi_0GUBgi3guWqUzT3gZOAC+iEyZcSLdw0=_9xWJEwHZg@mail.gmail.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Feb 27, 2019 at 09:17:42AM -0800, Linus Torvalds wrote:
> It all seems pretty ad-hoc, and we already _know_ that "asm volatile" is bad.

Ah, all I wanted was the ONCE thing and my inline asm foo sucks. If +m
gets us that, awesome.

But the ONCE thing defeats CSE (on purpose!) so for code-gen that
likes/wants that we then have to use the __this_cpu crud.