linux-kernel - Re: [PATCH 1/1] lockdep: Kill held_lock->check and "int check" arg of __lock

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Message-ID: <20140113170609.GA9873@redhat.com>
Date:	Mon, 13 Jan 2014 18:06:09 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Steven Rostedt <rostedt@...dmis.org>,
	Paul McKenney <paulmck@...ux.vnet.ibm.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 1/1] lockdep: Kill held_lock->check and "int check" arg
	of __lock_acquire()

On 01/12, Oleg Nesterov wrote:
>
> The "int check" argument of lock_acquire() and held_lock->check
> are misleading and unneeded. This is only used as a boolean, 2
> denotes "true", everything else is "false". And this boolean is
> always equal to prove_locking.
>
> The only exception is __lockdep_no_validate__ which should make
> this condition "false" in validate_chain().

And I missed mark_irqflags(),

> @@ -3136,7 +3130,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
>  	hlock->holdtime_stamp = lockstat_clock();
>  #endif
>
> -	if (check == 2 && !mark_irqflags(curr, hlock))
> +	if (prove_locking && !mark_irqflags(curr, hlock))
>  		return 0;

This change is not right, at least it is not equivalent.

And I just realized that rcu_lock_acquire() does lock_acquire(check => 1).
Probably we can mark rcu_lock_map's as __lockdep_no_validate__.

Anything else I missed?

Oleg.

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