linux-kernel - Re: [PATCH v1 2/5] seqlock: Use unique prefix for seqcount

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Date:   Fri, 28 Aug 2020 10:27:54 +0200
From:   peterz@...radead.org
To:     "Ahmed S. Darwish" <a.darwish@...utronix.de>
Cc:     Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Sebastian A. Siewior" <bigeasy@...utronix.de>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 2/5] seqlock: Use unique prefix for seqcount_t
 property accessors

On Fri, Aug 28, 2020 at 03:07:07AM +0200, Ahmed S. Darwish wrote:
> Differentiate the first group by using "__seqcount_t_" as prefix. This
> also conforms with the rest of seqlock.h naming conventions.

>  #define __seqprop_case(s, locktype, prop)				\
>  	seqcount_##locktype##_t: __seqcount_##locktype##_##prop((void *)(s))
>  
>  #define __seqprop(s, prop) _Generic(*(s),				\
> -	seqcount_t:		__seqcount_##prop((void *)(s)),		\
> +	seqcount_t:		__seqcount_t_##prop((void *)(s)),	\
>  	__seqprop_case((s),	raw_spinlock,	prop),			\
>  	__seqprop_case((s),	spinlock,	prop),			\
>  	__seqprop_case((s),	rwlock,		prop),			\

If instead you do:

#define __seqprop_case(s, _lockname, prop) \
	seqcount##_lockname##_t: __seqcount##_lockname##_##prop((void *)(s))

You can have:

	__seqprop_case((s),	,		prop),
	__seqprop_case((s),	_raw_spinlock,	prop),
	__seqprop_case((s),	_spinlock,	prop),
	__seqprop_case((s),	_rwlock,	prop),
	__seqprop_case((s),	_mutex,		prop),
	__seqprop_case((s),	_ww_mutex,	prop),

And it's all good again.

Although arguably we should do something like s/__seqcount/__seqprop/
over this lot.