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Date: Tue, 27 Jun 2006 11:28:56 +0200
Message-ID: <s5hejxb7xrb.wl%tiwai@suse.de>
From: Takashi Iwai <tiwai@suse.de>
To: Dave Jones <davej@redhat.com>
Cc: alsa-devel@lists.sourceforge.net,
       Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: list corruption on removal of snd_seq_dummy
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At Mon, 26 Jun 2006 23:27:38 -0400,
Dave Jones wrote:
> 
> On Fri, Jun 23, 2006 at 12:47:46PM +0200, Takashi Iwai wrote:
>  
>  > > The code in question is doing..
>  > > 
>  > >         __list_add(&deleted_list,
>  > >                client->ports_list_head.prev,
>  > >                client->ports_list_head.next);
>  > > 
>  > > which looks fishy, as those two elements aren't going to be consecutive,
>  > > as __list_add expects.
>  > 
>  > I think the code behaves correctly but probably misusing __list_add().
>  > It movies the whole entries from an existing list_head A
>  > (clients->ports_list_head) to a new list_head B (deleted_list).
>  > The above is exapnded:
>  > 
>  > 	A->next->prev = B;
>  > 	B->next = A->next;
>  > 	B->prev = A->prev;
>  > 	A->prev->next = B;
>  > 
>  > Any better way to achieve it using standard macros?
> 
> Why can't you just list_move() the elements ?

No, list_move() can't move the whole elements without loop.

A solution is

	list_add(B, A);
	list_del_init(A);

(although this introduces a bit more code :)


Takashi