linux-kernel - Re: [RFC v7 14/19] lockdep: Take read/write status in consideration when generate chainkey

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Message-ID: <20200821174132.GR3982@worktop.programming.kicks-ass.net>
Date:   Fri, 21 Aug 2020 19:41:32 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Boqun Feng <boqun.feng@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        Waiman Long <longman@...hat.com>
Subject: Re: [RFC v7 14/19] lockdep: Take read/write status in consideration
 when generate chainkey


So far so good, excellent work.

On Fri, Aug 07, 2020 at 03:42:33PM +0800, Boqun Feng wrote:
> @@ -371,6 +371,21 @@ static struct hlist_head classhash_table[CLASSHASH_SIZE];
>  
>  static struct hlist_head chainhash_table[CHAINHASH_SIZE];
>  
> +/*
> + * the id of held_lock
> + */
> +static inline u16 hlock_id(struct held_lock *hlock)
> +{
> +	BUILD_BUG_ON(MAX_LOCKDEP_KEYS_BITS + 2 > 16);
> +
> +	return (hlock->class_idx | (hlock->read << MAX_LOCKDEP_KEYS_BITS));
> +}
> +
> +static inline unsigned int chain_hlock_class_idx(u16 hlock_id)
> +{
> +	return hlock_id & MAX_LOCKDEP_KEYS;

But did that want to be:

	return hlock_id & (MAX_LOCKDEP_KEYS-1);

?

> +}