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Date: Tue, 17 Jan 2006 16:56:02 -0800
From: Andrew Morton <akpm@osdl.org>
To: "Paolo 'Blaisorblade' Giarrusso" <blaisorblade@yahoo.it>
Cc: jdike@addtoit.com, linux-kernel@vger.kernel.org,
       user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [PATCH 6/9] uml: avoid malloc to sleep in atomic sections
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"Paolo 'Blaisorblade' Giarrusso" <blaisorblade@yahoo.it> wrote:
>
> +int __cant_sleep(void) {
> +	return in_atomic() || irqs_disabled() || in_interrupt();

aww, man, this is awful.  Code is supposed to know what context it's
running in, not go fishing about in core internals trying to fix up its own
confusion.

> +	/* Is in_interrupt() really needed? */
>  }

Yes, it is.  in_atomic() is a no-op on !PREEMPT and local irq's can be
enabled in soft- or hard- interrupt context, so irqs_disabled() will return
0.