linux-kernel - Re: Is spin_is_locked() safe to use with BUG_ON()/WARN

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Message-ID: <6788.1369321955@warthog.procyon.org.uk>
Date:	Thu, 23 May 2013 16:12:35 +0100
From:	David Howells <dhowells@...hat.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	dhowells@...hat.com, Ingo Molnar <mingo@...nel.org>,
	milosz@...in.com,
	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Is spin_is_locked() safe to use with BUG_ON()/WARN_ON()?

Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> We do *not* want to add some crazy "spin_is_nt_locked". We just want
> to get rid of these idiotic debug tests.

Generally, I think you are right, though there are also some checks in
deallocation routines that check that a spinlock is not currently held before
releasing the memory holding it - should those be allowed to stay?  I'd be
tempted to wrap the whole check in something, perhaps an "spin_lock_uninit()"
and move the check to a header file.  Would this be useful for lockdep or
anything like that?

David
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