From: David Howells <dhowells@redhat.com>
In-Reply-To: <20040127191155.GA12128@tsunami.ccur.com> 
References: <20040127191155.GA12128@tsunami.ccur.com> 
To: joe.korty@ccur.com
Cc: akpm@osdl.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] volatile may be needed in rwsem 
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Date: Tue, 27 Jan 2004 19:19:40 +0000
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> 'flags' should be declared volatile as rwsem_down_failed_common() spins
> waiting for this to change.  Untested.

Is it though? Does this fix an error?

The thing is, we make a function call inside of the loop:

	/* wait to be given the lock */
	for (;;) {
		if (!waiter->flags)
			break;
		schedule();
		set_task_state(tsk, TASK_UNINTERRUPTIBLE);
	}

Which might preclude that need. I'm not entirely sure, though... it's one of
those compiler black magic things.

I suppose it can't hurt...

David
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