netdev - Re: [BUG] znet.c sleeping function called from invalid context

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Date:	Wed, 7 Oct 2009 14:44:45 -0400
From:	Mike Frysinger <vapier.adi@...il.com>
To:	Michael Hennerich <michael.hennerich@...log.com>
Cc:	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	Linux Kernlel Mailing List <linux-kernel@...r.kernel.org>,
	Alexander Strakh <strakh@...ras.ru>,
	uclinux-dist-devel <uclinux-dist-devel@...ckfin.uclinux.org>
Subject: Re: [BUG] znet.c sleeping function called from invalid context

On Wed, Oct 7, 2009 at 14:47, Alexander Strakh wrote:
>        KERNEL_VERSION: 2.6.31
>        DESCRIBE:
> Driver drivers/net/znet.c might sleep in atomic context, because it calls
> free_dma under claim_dma_lock:
>
> .drivers/net/znet.c:
>  168 static int znet_request_resources (struct net_device *dev)
> ...
>  189        flags = claim_dma_lock();
>  190        free_dma (znet->tx_dma);
>  191        release_dma_lock (flags);
> ...
>
> Path to might_sleep macro from znet_request_resources:
> 1. znet_request_resources calls free_dma at
> arch/blackfin/kernel/bfin_dma_5xx.c:181
> 2. free_dma calls arch/blackfin/kernel/bfin_dma_5xx.c:195

i dont think we need the dmalock mutex.  it's only used to protect
read/writes to .chan_status, and that should be atomic already.
-mike
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