Re: [PATCH] swiotlb: suppress warning when __GFP_NOWARN is set v2

[Konrad Rzeszutek Wilk]

On Tue, Jan 02, 2018 at 01:13:58PM +0100, Christian König wrote:
> TTM tries to allocate coherent memory in chunks of 2MB first to improve
> TLB efficiency and falls back to allocating 4K pages if that fails.
> 
> Suppress the warning when the 2MB allocations fails since there is a
> valid fall back path.
> 
> v2: suppress warnings from swiotlb_tbl_map_single as well
> 
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> Reported-by: Mike Galbraith <efault@xxxxxx>
> Bug: https://bugs.freedesktop.org/show_bug.cgi?id=104082
> CC: stable@xxxxxxxxxxxxxxx
> ---
>  lib/swiotlb.c | 44 +++++++++++++++++++++++++++++---------------
>  1 file changed, 29 insertions(+), 15 deletions(-)
> 
> diff --git a/lib/swiotlb.c b/lib/swiotlb.c
> index cea19aaf303c..ed443d65a8e2 100644
> --- a/lib/swiotlb.c
> +++ b/lib/swiotlb.c
> @@ -490,11 +490,11 @@ static void swiotlb_bounce(phys_addr_t orig_addr, phys_addr_t tlb_addr,
>  	}
>  }
>  
> -phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
> -				   dma_addr_t tbl_dma_addr,
> -				   phys_addr_t orig_addr, size_t size,
> -				   enum dma_data_direction dir,
> -				   unsigned long attrs)
> +phys_addr_t _swiotlb_tbl_map_single(struct device *hwdev,

Just ditch the '_swiotlb' and make it 'tbl_map_single'
> +				    dma_addr_t tbl_dma_addr,
> +				    phys_addr_t orig_addr, size_t size,
> +				    enum dma_data_direction dir,
> +				    unsigned long attrs, bool warn)
>  {
>  	unsigned long flags;
>  	phys_addr_t tlb_addr;
> @@ -586,7 +586,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
>  
>  not_found:
>  	spin_unlock_irqrestore(&io_tlb_lock, flags);
> -	if (printk_ratelimit())
> +	if (warn && printk_ratelimit())
>  		dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes)\n", size);
>  	return SWIOTLB_MAP_ERROR;
>  found:
> @@ -605,6 +605,16 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
>  
>  	return tlb_addr;
>  }
> +
> +phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
> +				   dma_addr_t tbl_dma_addr,
> +				   phys_addr_t orig_addr, size_t size,
> +				   enum dma_data_direction dir,
> +				   unsigned long attrs)

Hm, could be my editor, but are the parameters on the same line as 'struct device *hwdev'?

> +{
> +	return _swiotlb_tbl_map_single(hwdev, tbl_dma_addr, orig_addr,
> +				       size, dir, attrs, true);
> +}
>  EXPORT_SYMBOL_GPL(swiotlb_tbl_map_single);
>  
>  /*
> @@ -613,7 +623,7 @@ EXPORT_SYMBOL_GPL(swiotlb_tbl_map_single);
>  
>  static phys_addr_t
>  map_single(struct device *hwdev, phys_addr_t phys, size_t size,
> -	   enum dma_data_direction dir, unsigned long attrs)
> +	   enum dma_data_direction dir, unsigned long attrs, bool warn)
>  {
>  	dma_addr_t start_dma_addr;
>  
> @@ -624,8 +634,8 @@ map_single(struct device *hwdev, phys_addr_t phys, size_t size,
>  	}
>  
>  	start_dma_addr = swiotlb_phys_to_dma(hwdev, io_tlb_start);
> -	return swiotlb_tbl_map_single(hwdev, start_dma_addr, phys, size,
> -				      dir, attrs);
> +	return _swiotlb_tbl_map_single(hwdev, start_dma_addr, phys, size,
> +				       dir, attrs, warn);
>  }
>  
>  /*
> @@ -713,6 +723,7 @@ void *
>  swiotlb_alloc_coherent(struct device *hwdev, size_t size,
>  		       dma_addr_t *dma_handle, gfp_t flags)
>  {
> +	bool warn = !(flags & __GFP_NOWARN);
>  	dma_addr_t dev_addr;
>  	void *ret;
>  	int order = get_order(size);
> @@ -739,7 +750,7 @@ swiotlb_alloc_coherent(struct device *hwdev, size_t size,
>  		 * will grab memory from the lowest available address range.
>  		 */
>  		phys_addr_t paddr = map_single(hwdev, 0, size,
> -					       DMA_FROM_DEVICE, 0);
> +					       DMA_FROM_DEVICE, 0, warn);
>  		if (paddr == SWIOTLB_MAP_ERROR)
>  			goto err_warn;
>  
> @@ -769,9 +780,11 @@ swiotlb_alloc_coherent(struct device *hwdev, size_t size,
>  	return ret;
>  
>  err_warn:
> -	pr_warn("swiotlb: coherent allocation failed for device %s size=%zu\n",
> -		dev_name(hwdev), size);
> -	dump_stack();
> +	if (warn) {

&& printk_ratelimit() ?

> +		pr_warn("swiotlb: coherent allocation failed for device %s size=%zu\n",
> +			dev_name(hwdev), size);
> +		dump_stack();
> +	}
>  
>  	return NULL;
>  }
> @@ -851,7 +864,7 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
>  	trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force);
>  
>  	/* Oh well, have to allocate and map a bounce buffer. */
> -	map = map_single(dev, phys, size, dir, attrs);
> +	map = map_single(dev, phys, size, dir, attrs, true);
>  	if (map == SWIOTLB_MAP_ERROR) {
>  		swiotlb_full(dev, size, dir, 1);
>  		return swiotlb_phys_to_dma(dev, io_tlb_overflow_buffer);
> @@ -989,7 +1002,8 @@ swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems,
>  		if (swiotlb_force == SWIOTLB_FORCE ||
>  		    !dma_capable(hwdev, dev_addr, sg->length)) {
>  			phys_addr_t map = map_single(hwdev, sg_phys(sg),
> -						     sg->length, dir, attrs);
> +						     sg->length, dir, attrs,
> +						     true);

s/true/true /*Always warn.*/

>  			if (map == SWIOTLB_MAP_ERROR) {
>  				/* Don't panic here, we expect map_sg users
>  				   to do proper error handling. */
> -- 
> 2.11.0
>