linux-kernel - Re: [PATCH] dma-debug: fix to not have dependency on get_dma

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Message-ID: <1352999057.2532.16.camel@lorien2>
Date:	Thu, 15 Nov 2012 10:04:17 -0700
From:	Shuah Khan <shuah.khan@...com>
To:	Marek Szyprowski <m.szyprowski@...sung.com>
Cc:	Joerg Roedel <joro@...tes.org>,
	Andrew Morton <akpm@...ux-foundation.org>, kubakici@...pl,
	stern@...land.harvard.edu, Greg KH <gregkh@...uxfoundation.org>,
	Mark Salter <msalter@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, konrad.wilk@...cle.com,
	shuahkhan@...il.com
Subject: Re: [PATCH] dma-debug: fix to not have dependency on get_dma_ops()
 interface

On Mon, 2012-11-05 at 08:59 -0500, Konrad Rzeszutek Wilk wrote:
> On Sat, Nov 03, 2012 at 05:00:07PM -0600, Shuah Khan wrote:
> > dma-debug depends on get_dma_ops() interface. Several architectures
> > do not define dma_ops and get_dma_ops(). When dma debug interfaces are
> > used on an architecture (e.g: c6x) that doesn't define get_dmap_ops(),
> > compilation fails. Changing dma-debug to call dma_mapping_error() instead
> > of defining its own that calls get_dma_ops(), such that the internal use of
> > dma_mapping_error() doesn't interfere with the debug_dma_mapping_error()
> > interface's mapping error checks. Moving dma_mapping_error() checks in
> > check_unmap() under the dma debug entry not found is sufficient to fix the
> > problem.
> 
> OK.
> 
> It looks ok to me.

Marek,

Following up on our off-line discussion about your offer to pull
dma-debug patch and the arch patches that call debug_dma_mapping_error()
interface in to your tree. Thanks again for offering to do that. This
patch is depends on the first debug_dma_mapping_error() patch that is in
linux-next and in the dma-debug tree.

Reference - https://lkml.org/lkml/2012/10/8/296

linux-next commit-id is commit 6c9c6d6301287e369a754d628230fa6e50cdb74b

You will need to pull these two first into your tree and then the arch
patches - I will include you on my responses to those patches shortly.

-- Shuah

> 
> > -   debug_dma_mapping_error() - need internal mapping error routine to
> > -   avoid debug checks */
> > -#ifndef DMA_ERROR_CODE
> > -#define DMA_ERROR_CODE 0
> > -#endif
> > -static inline int has_mapping_error(struct device *dev, dma_addr_t dma_addr)
> > -{
> > -	const struct dma_map_ops *ops = get_dma_ops(dev);
> > -	if (ops->mapping_error)
> > -		return ops->mapping_error(dev, dma_addr);
> > -
> > -	return (dma_addr == DMA_ERROR_CODE);
> > -}
> > -
> >  static void check_unmap(struct dma_debug_entry *ref)
> >  {
> >  	struct dma_debug_entry *entry;
> >  	struct hash_bucket *bucket;
> >  	unsigned long flags;
> >  
> > -	if (unlikely(has_mapping_error(ref->dev, ref->dev_addr))) {
> > -		err_printk(ref->dev, NULL, "DMA-API: device driver tries "
> > -			   "to free an invalid DMA memory address\n");
> > -		return;
> > -	}
> > -
> >  	bucket = get_hash_bucket(ref, &flags);
> >  	entry = bucket_find_exact(bucket, ref);
> >  
> >  	if (!entry) {
> > +		if (dma_mapping_error(ref->dev, ref->dev_addr)) {
> > +			err_printk(ref->dev, NULL,
> > +				   "DMA-API: device driver tries "
> > +				   "to free an invalid DMA memory address\n");
> > +			return;
> > +		}
> >  		err_printk(ref->dev, NULL, "DMA-API: device driver tries "
> >  			   "to free DMA memory it has not allocated "
> >  			   "[device address=0x%016llx] [size=%llu bytes]\n",
> > @@ -1055,7 +1040,7 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
> >  	if (unlikely(global_disable))
> >  		return;
> >  
> > -	if (unlikely(has_mapping_error(dev, dma_addr)))
> > +	if (dma_mapping_error(dev, dma_addr))
> >  		return;
> >  
> >  	entry = dma_entry_alloc();
> > -- 
> > 1.7.9.5
> > 
> > 


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