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Date:   Tue, 21 Jan 2020 15:42:29 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Alex Kogan <alex.kogan@oracle.com>
Cc:     linux@armlinux.org.uk, mingo@redhat.com, will.deacon@arm.com,
        arnd@arndb.de, longman@redhat.com, linux-arch@vger.kernel.org,
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        steven.sistare@oracle.com, daniel.m.jordan@oracle.com,
        dave.dice@oracle.com
Subject: Re: [PATCH v8 3/5] locking/qspinlock: Introduce CNA into the slow
 path of qspinlock
Message-ID: <20200121144229.GN14914@hirez.programming.kicks-ass.net>
References: <20191230194042.67789-1-alex.kogan@oracle.com>
 <20191230194042.67789-4-alex.kogan@oracle.com>
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On Mon, Dec 30, 2019 at 02:40:40PM -0500, Alex Kogan wrote:
> +#define pv_wait_head_or_lock		cna_pre_scan

Also inconsitent naming.

> +__always_inline u32 cna_pre_scan(struct qspinlock *lock,
> +				  struct mcs_spinlock *node)
> +{
> +	struct cna_node *cn = (struct cna_node *)node;
> +
> +	cn->pre_scan_result = cna_scan_main_queue(node, node);
> +
> +	return 0;
> +}

The thinking here is that we're trying to make use of the time otherwise
spend spinning on atomic_cond_read_acquire(), to search for a potential
unlock candidate?

Surely that deserves a comment.