linux-kernel - Re: dma_debug_device_change() gives bogus errors

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Message-ID: <20090424121840.GO17438@amd.com>
Date:	Fri, 24 Apr 2009 14:18:40 +0200
From:	Joerg Roedel <joerg.roedel@....com>
To:	David Vrabel <david.vrabel@....com>
CC:	Kernel development list <linux-kernel@...r.kernel.org>
Subject: Re: dma_debug_device_change() gives bogus errors

On Fri, Apr 24, 2009 at 12:20:04PM +0100, David Vrabel wrote:
> dma_debug_device_change() gives bogus errors if a driver unmaps dma
> buffers within its driver->remove() method.  This is because the
> BUS_NOTIFY_UNBIND_DRIVER notification is raised before calling
> driver->remove() (see __device_release_driver() in drivers/base/dd.c).
> 
> By the time my driver->remove() completes, there are no DMA mappings
> (debug_dma_dump_mappings() produces no output).
> 
> Also, somewhat surprisingly, it only prints the error the first time the
> driver is unbound.

Thanks for the report. This is being worked on already. I will disable
this check for 2.6.30 and try to get a solution upstream for 2.6.31.

Joerg

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