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Date:   Sat, 2 Sep 2017 21:35:41 +0300
From:   Alexey Khoroshilov <khoroshilov@...ras.ru>
To:     Jack Pham <jackp@...eaurora.org>
Cc:     Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        ldv-project@...uxtesting.org
Subject: Re: [PATCH] usb: gadget: pch_udc: add checks for dma mapping errors

On 24.08.2017 04:02, Jack Pham wrote:
> On Thu, Aug 24, 2017 at 01:47:08AM +0300, Alexey Khoroshilov wrote:
>> There are no checks for dma mapping errors in pch_udc.
>> Tha patch adds the checks and error handling code.
>> Compile tested only.
>>
>> Found by Linux Driver Verification project (linuxtesting.org).
>>
>> Signed-off-by: Alexey Khoroshilov <khoroshilov@...ras.ru>
>> ---
>>  drivers/usb/gadget/udc/pch_udc.c | 15 +++++++++++++--
>>  1 file changed, 13 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/usb/gadget/udc/pch_udc.c b/drivers/usb/gadget/udc/pch_udc.c
>> index 84dcbcd756f0..a305f8392082 100644
>> --- a/drivers/usb/gadget/udc/pch_udc.c
>> +++ b/drivers/usb/gadget/udc/pch_udc.c
>> @@ -1767,7 +1767,7 @@ static struct usb_request *pch_udc_alloc_request(struct usb_ep *usbep,
>>  	req->req.dma = DMA_ADDR_INVALID;
>>  	req->dma = DMA_ADDR_INVALID;
>>  	INIT_LIST_HEAD(&req->queue);
>> -	if (!ep->dev->dma_addr)
>> +	if (ep->dev->dma_addr != DMA_ADDR_INVALID)
>>  		return &req->req;
>>  	/* ep0 in requests are allocated from data pool here */
>>  	dma_desc = dma_pool_alloc(ep->dev->data_requests, gfp,
>> @@ -1879,6 +1879,13 @@ static int pch_udc_pcd_queue(struct usb_ep *usbep, struct usb_request *usbreq,
>>  							  usbreq->length,
>>  							  DMA_FROM_DEVICE);
>>  		}
>> +		if (dma_mapping_error(&dev->pdev->dev, req->dma)) {
>> +			req->dma = DMA_ADDR_INVALID;
>> +			retval = -ENOMEM;
>> +			if ((unsigned long)(usbreq->buf) & 0x03)
>> +				kfree(req->buf);
>> +			goto probe_end;
>> +		}
>>  		req->dma_mapped = 1;
>>  	}
>>  	if (usbreq->length > 0) {
>> @@ -2961,6 +2968,10 @@ static int init_dma_pools(struct pch_udc_dev *dev)
>>  	dev->dma_addr = dma_map_single(&dev->pdev->dev, ep0out_buf,
>>  				       UDC_EP0OUT_BUFF_SIZE * 4,
>>  				       DMA_FROM_DEVICE);
>> +	if (dma_mapping_error(&dev->pdev->dev, dev->dma_addr)) {
>> +		dev->dma_addr = DMA_ADDR_INVALID;
>> +		return -ENOMEM;
>> +	}
> 
> Wouldn't this driver be better off using the
> usb_gadget_{map,unmap}_request() functions provided by UDC core.c?
> dma_mapping_error() is provided for free that way.
> 

I think so, but it requires quite significant rework of the driver.
I would not do that without access to hardware.

--
Alexey

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