Date: Tue, 18 Jul 2017 10:25:55 +0900
From: Byungchul Park <byungchul.park@lge.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: mingo@kernel.org, tglx@linutronix.de, walken@google.com,
        boqun.feng@gmail.com, kirill@shutemov.name,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        akpm@linux-foundation.org, willy@infradead.org, npiggin@gmail.com,
        kernel-team@lge.com
Subject: Re: [PATCH v7 06/16] lockdep: Detect and handle hist_lock ring
 buffer overwrite
Message-ID: <20170718012554.GL20323@X58A-UD3R>
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On Thu, Jul 13, 2017 at 10:14:42AM +0200, Peter Zijlstra wrote:
> +static void __crossrelease_end(unsigned int *stamp)
> +{

[snip]

> +
> +	/*
> +	 * If we rewind past the tail; all of history is lost.
> +	 */
> +	if ((current->xhlock_idx_max - *stamp) < MAX_XHLOCKS_NR)
> +		return;
> +
> +	/*
> +	 * Invalidate the entire history..
> +	 */
> +	for (i = 0; i < MAX_XHLOCKS_NR; i++)
> +		invalidate_xhlock(&xhlock(i));
> +
> +	current->xhlock_idx = 0;
> +	current->xhlock_idx_hard = 0;
> +	current->xhlock_idx_soft = 0;
> +	current->xhlock_idx_hist = 0;
> +	current->xhlock_idx_max = 0;

I don't understand why you introduced this code, yet. Do we need this?

The other of your suggestion looks very good though..

> +}