linux-kernel - Re: [PATCH 1/7] introduce atomic_dec_and_lock

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Date:	Wed, 30 Aug 2006 11:59:48 +0200 (CEST)
From:	Roman Zippel <zippel@...ux-m68k.org>
To:	Kirill Korotaev <dev@...ru>
cc:	Andrew Morton <akpm@...l.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Christoph Hellwig <hch@...radead.org>,
	Pavel Emelianov <xemul@...nvz.org>,
	Andrey Savochkin <saw@...ru>, devel@...nvz.org,
	Rik van Riel <riel@...hat.com>, Andi Kleen <ak@...e.de>,
	Oleg Nesterov <oleg@...sign.ru>,
	Alexey Dobriyan <adobriyan@...l.ru>,
	Matt Helsley <matthltc@...ibm.com>,
	CKRM-Tech <ckrm-tech@...ts.sourceforge.net>
Subject: Re: [PATCH 1/7] introduce atomic_dec_and_lock_irqsave()

Hi,

On Tue, 29 Aug 2006, Kirill Korotaev wrote:

> --- ./kernel/user.c.dlirq	2006-07-10 12:39:20.000000000 +0400
> +++ ./kernel/user.c	2006-08-28 11:08:56.000000000 +0400
> @@ -108,15 +108,12 @@ void free_uid(struct user_struct *up)
> 	if (!up)
> 		return;
> 
> -	local_irq_save(flags);
> -	if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
> +	if (atomic_dec_and_lock_irqsave(&up->__count, &uidhash_lock, flags)) {
> 		uid_hash_remove(up);
> 		spin_unlock_irqrestore(&uidhash_lock, flags);
> 		key_put(up->uid_keyring);
> 		key_put(up->session_keyring);
> 		kmem_cache_free(uid_cachep, up);
> -	} else {
> -		local_irq_restore(flags);
> 	}
> }

Why does this need protection against interrupts?

bye, Roman
-
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