linux-kernel - [PATCH 0/1] lockdep: Kill held_lock->check and "int check" arg of __lock

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Message-ID: <20140112174532.GA12147@redhat.com>
Date:	Sun, 12 Jan 2014 18:45:32 +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: [PATCH 0/1] lockdep: Kill held_lock->check and "int check" arg of
	__lock_acquire()

On 01/12, Ingo Molnar wrote:
>
> * Peter Zijlstra <peterz@...radead.org> wrote:
>
> > > But what I really can't understans is what "check == 0" means? It
> > > seems that in fact it can be 1 or 2? Or, iow, "check == 0" is
> > > actually equivalent to "check == 1" ?
> >
> > Hmm indeed, the comment in lockdep.h says 0 means no checks at all,
> > but the code doesn't actually appear to work like that. I'm not sure
> > it ever did or not, I'd have to go dig through history.
> >
> > That said, given the current state it certainly looks like we can
> > remove the check argument.
> >
> > Ingo?
>
> Agreed.

OK, could you and Peter review the patch?

If it passes the review I'll send another one which changes the callers
of lock_acquire(). And trace_lock_acquire() should be trivially updated
too.

But could someone please explain me what should lockdep_no_validate
actually do? 1704f47b5 "lockdep: Add novalidate class for dev->mutex
conversion" doesn't tell which kind of warnings it tries to avoid,
and it looks buggy (see another email from me).

Oleg.

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