From: Linus Torvalds <torvalds@linux-foundation.org>
To: Kumar Gala <galak@kernel.crashing.org>
Cc: peterz@infradead.org, linux-kernel@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>,
linuxppc-dev@ozlabs.org, mingo@elte.hu, tglx@linutronix.de
Subject: Re: [PATCH] spinlock: __raw_spin_is_locked() should return true for UP
Date: Tue, 18 Aug 2009 19:40:16 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.2.01.0908181937400.3158@localhost.localdomain> (raw)
In-Reply-To: <BB2762BC-C760-4D4C-BDCF-76EFD3E1B18D@kernel.crashing.org>
On Tue, 18 Aug 2009, Kumar Gala wrote:
>
> I agree its a little too easy to abuse spin_is_locked. However we should be
> consistent between spin_is_locked on UP between with and without
> CONFIG_DEBUG_SPINLOCK enabled.
No we shouldn't.
With CONFIG_DEBUG_SPINLOCK, you have an actual lock variable for debugging
purposes, so spin_is_locked() can clearly return a _valid_ answer, and
should do so.
Without DEBUG_SPINLOCK, there isn't any answer to return.
So there's no way we can or should be consistent. In one case an answer
exists, in another one the answer is meaningless and doesn't exist.
> How much of this do we want to try and address in .31?
Absolutely nothing.
> The PPC test really should be using assert_spin_locked and I'll send a patch
> to Ben for that.
Yes, that's the correct fix.
Linus
next prev parent reply other threads:[~2009-08-19 2:41 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-18 22:42 [PATCH] spinlock: __raw_spin_is_locked() should return true for UP Kumar Gala
2009-08-18 23:20 ` Linus Torvalds
2009-08-18 23:36 ` Steven Rostedt
2009-08-18 23:52 ` Linus Torvalds
2009-08-19 0:07 ` Steven Rostedt
2009-08-19 1:17 ` Kumar Gala
2009-08-19 2:40 ` Linus Torvalds [this message]
2009-08-19 9:31 ` Olivier Galibert
2009-08-19 9:38 ` Peter Zijlstra
2009-08-19 18:50 ` Scott Wood
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