[PATCH] xhci: Remove unused value len from xhci_unmap_temp_buf

[PATCH] xhci: Remove unused value len from xhci_unmap_temp_buf

[zhangkun4jr]

From: Zhang Kun <zhangkun@cdjrlc.com>

The value assigned to len by sg_pcopy_from_buffer() never used for
anything, so remove it.

Signed-off-by: Zhang Kun <zhangkun@cdjrlc.com>
---
 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);
-- 
2.17.1

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

[Greg Kroah-Hartman]

On Sat, Mar 06, 2021 at 08:06:44PM +0800, zhangkun4jr@163.com wrote:
> From: Zhang Kun <zhangkun@cdjrlc.com>
> 
> The value assigned to len by sg_pcopy_from_buffer() never used for
> anything, so remove it.
> 
> Signed-off-by: Zhang Kun <zhangkun@cdjrlc.com>
> ---
>  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?

thanks,

greg k-h

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@163.com wrote:
>> From: Zhang Kun <zhangkun@cdjrlc.com>
>>
>> The value assigned to len by sg_pcopy_from_buffer() never used for
>> anything, so remove it.
>>
>> Signed-off-by: Zhang Kun <zhangkun@cdjrlc.com>
>> ---
>>  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

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

[Greg Kroah-Hartman]

On Sun, Mar 07, 2021 at 09:14:26AM +0800, Zhangkun wrote:
> On 3/7/21 12:25 AM, Greg Kroah-Hartman wrote:
> > On Sat, Mar 06, 2021 at 08:06:44PM +0800, zhangkun4jr@163.com wrote:
> >> From: Zhang Kun <zhangkun@cdjrlc.com>
> >>
> >> The value assigned to len by sg_pcopy_from_buffer() never used for
> >> anything, so remove it.
> >>
> >> Signed-off-by: Zhang Kun <zhangkun@cdjrlc.com>
> >> ---
> >>  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.

Why should you not check that the number of bytes was copied properly?

thanks,

greg k-h