linux-kernel - Re: [RFC][PATCH] netconsole: avoid deadlock on printk from driver code

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Message-Id: <20080814.151502.251134900.davem@davemloft.net>
Date:	Thu, 14 Aug 2008 15:15:02 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	penberg@...helsinki.fi
Cc:	vegard.nossum@...il.com, vegardno@....uio.no,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	jgarzik@...ox.com, adobriyan@...il.com
Subject: Re: [RFC][PATCH] netconsole: avoid deadlock on printk from driver
 code

From: Pekka J Enberg <penberg@...helsinki.fi>
Date: Thu, 14 Aug 2008 16:44:32 +0300 (EEST)

> @@ -598,6 +598,7 @@
>  
>  	spinlock_t		lock;
>  	spinlock_t		rx_lock;
> +	spinlock_t		tx_lock;
>  
>  	chip_t			chipset;
>  	u32			rx_config;

Why create a special purpose lock when the generic networking
already is taking a lock for you to proect the TX path?

Furthermore, as I just described in another reply, netpoll
already knows that it might need to trylock() attempt on this
lock in order to avoid the very deadlocks this thread is
about.
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