Date:   Mon, 6 Mar 2023 12:22:40 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Marcelo Tosatti <mtosatti@redhat.com>
Cc:     Christoph Lameter <cl@linux.com>,
        Aaron Tomlin <atomlin@atomlin.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Russell King <linux@armlinux.org.uk>,
        Huacai Chen <chenhuacai@kernel.org>,
        Heiko Carstens <hca@linux.ibm.com>, x86@kernel.org
Subject: Re: [PATCH v4 05/12] this_cpu_cmpxchg: x86: switch this_cpu_cmpxchg
 to locked, add _local function
Message-ID: <20230306112240.GB1267364@hirez.programming.kicks-ass.net>
References: <20230305133657.255737580@redhat.com>
 <20230305134053.537803923@redhat.com>
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On Sun, Mar 05, 2023 at 10:37:02AM -0300, Marcelo Tosatti wrote:
> Goal is to have vmstat_shepherd to transfer from
> per-CPU counters to global counters remotely. For this,
> an atomic this_cpu_cmpxchg is necessary.
> 
> Following the kernel convention for cmpxchg/cmpxchg_local,
> change x86's this_cpu_cmpxchg_ helpers to be atomic.
> and add this_cpu_cmpxchg_local_ helpers which are not atomic.

Urgh.. much hate for this. this_cpu_*() is local, per definition,
always.