Re: [PATCH] xhci: Remove unused value len from xhci_unmap_temp_buf

[Zhangkun]

On 3/7/21 12:25 AM, Greg Kroah-Hartman wrote:
> On Sat, Mar 06, 2021 at 08:06:44PM +0800, zhangkun4jr@xxxxxxx wrote:
>> From: Zhang Kun <zhangkun@xxxxxxxxxx>
>>
>> The value assigned to len by sg_pcopy_from_buffer() never used for
>> anything, so remove it.
>>
>> Signed-off-by: Zhang Kun <zhangkun@xxxxxxxxxx>
>> ---
>>  drivers/usb/host/xhci.c | 3 +--
>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
>> index bd27bd670104..6ebda89d476c 100644
>> --- a/drivers/usb/host/xhci.c
>> +++ b/drivers/usb/host/xhci.c
>> @@ -1335,7 +1335,6 @@ static bool xhci_urb_temp_buffer_required(struct usb_hcd *hcd,
>>  
>>  static void xhci_unmap_temp_buf(struct usb_hcd *hcd, struct urb *urb)
>>  {
>> -	unsigned int len;
>>  	unsigned int buf_len;
>>  	enum dma_data_direction dir;
>>  
>> @@ -1351,7 +1350,7 @@ static void xhci_unmap_temp_buf(struct usb_hcd *hcd, struct urb *urb)
>>  				 dir);
>>  
>>  	if (usb_urb_dir_in(urb))
>> -		len = sg_pcopy_from_buffer(urb->sg, urb->num_sgs,
>> +		sg_pcopy_from_buffer(urb->sg, urb->num_sgs,
>>  					   urb->transfer_buffer,
>>  					   buf_len,
>>  					   0);
> 
> SHouldn't this be checked instead of ignored?
>

Hi, Greg.
Considering your tips I checked sg_pcopy_from_buffer(). it copys data
from urb->transfer_buffer to urb->sg, and only returns 0 or the 
'number of copied bytes', and seems to has no other exception branchs
that need to be checked. So I think it should be ingnored.

It may also be that I missed something, if that's the case, please
correct me.

Thanks,

Zhang