[PATCH v2] usb: gadget: aspeed_udc: fix handling of tx_len == 0

[PATCH v2] usb: gadget: aspeed_udc: fix handling of tx_len == 0

[Dan Carpenter]

The bug is that we should still enter this loop if "tx_len" is zero.

Reported-by: Neal Liu <neal_liu@aspeedtech.com>
Fixes: c09b1f372e74 ("usb: gadget: aspeed_udc: cleanup loop in ast_dma_descriptor_setup()")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
v2: Remove the unnecessary "chunk >= 0" condition

 drivers/usb/gadget/udc/aspeed_udc.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/gadget/udc/aspeed_udc.c b/drivers/usb/gadget/udc/aspeed_udc.c
index d75a4e070bf7..6ff02acc5662 100644
--- a/drivers/usb/gadget/udc/aspeed_udc.c
+++ b/drivers/usb/gadget/udc/aspeed_udc.c
@@ -476,6 +476,7 @@ static int ast_dma_descriptor_setup(struct ast_udc_ep *ep, u32 dma_buf,
 {
 	struct ast_udc_dev *udc = ep->udc;
 	struct device *dev = &udc->pdev->dev;
+	bool last = false;
 	int chunk, count;
 	u32 offset;
 
@@ -493,14 +494,16 @@ static int ast_dma_descriptor_setup(struct ast_udc_ep *ep, u32 dma_buf,
 	       "tx_len", tx_len);
 
 	/* Create Descriptor Lists */
-	while (chunk > 0 && count < AST_UDC_DESCS_COUNT) {
+	while (!last && count < AST_UDC_DESCS_COUNT) {
 
 		ep->descs[ep->descs_wptr].des_0 = dma_buf + offset;
 
-		if (chunk > ep->chunk_max)
+		if (chunk > ep->chunk_max) {
 			ep->descs[ep->descs_wptr].des_1 = ep->chunk_max;
-		else
+		} else {
 			ep->descs[ep->descs_wptr].des_1 = chunk;
+			last = true;
+		}
 
 		chunk -= ep->chunk_max;
 
-- 
2.35.1

RE: [PATCH v2] usb: gadget: aspeed_udc: fix handling of tx_len == 0

[Neal Liu]

> The bug is that we should still enter this loop if "tx_len" is zero.
> 
> Reported-by: Neal Liu <neal_liu@aspeedtech.com>
> Fixes: c09b1f372e74 ("usb: gadget: aspeed_udc: cleanup loop in
> ast_dma_descriptor_setup()")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> v2: Remove the unnecessary "chunk >= 0" condition

I mean v1 looks good to me.
Sorry if you are misunderstanding.

> 
>  drivers/usb/gadget/udc/aspeed_udc.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/gadget/udc/aspeed_udc.c
> b/drivers/usb/gadget/udc/aspeed_udc.c
> index d75a4e070bf7..6ff02acc5662 100644
> --- a/drivers/usb/gadget/udc/aspeed_udc.c
> +++ b/drivers/usb/gadget/udc/aspeed_udc.c
> @@ -476,6 +476,7 @@ static int ast_dma_descriptor_setup(struct ast_udc_ep
> *ep, u32 dma_buf,  {
>  	struct ast_udc_dev *udc = ep->udc;
>  	struct device *dev = &udc->pdev->dev;
> +	bool last = false;
>  	int chunk, count;
>  	u32 offset;
> 
> @@ -493,14 +494,16 @@ static int ast_dma_descriptor_setup(struct
> ast_udc_ep *ep, u32 dma_buf,
>  	       "tx_len", tx_len);
> 
>  	/* Create Descriptor Lists */
> -	while (chunk > 0 && count < AST_UDC_DESCS_COUNT) {
> +	while (!last && count < AST_UDC_DESCS_COUNT) {
> 
>  		ep->descs[ep->descs_wptr].des_0 = dma_buf + offset;
> 
> -		if (chunk > ep->chunk_max)
> +		if (chunk > ep->chunk_max) {
>  			ep->descs[ep->descs_wptr].des_1 = ep->chunk_max;
> -		else
> +		} else {
>  			ep->descs[ep->descs_wptr].des_1 = chunk;
> +			last = true;
> +		}
> 
>  		chunk -= ep->chunk_max;
> 
> --
> 2.35.1

Re: [PATCH v2] usb: gadget: aspeed_udc: fix handling of tx_len == 0

[Greg Kroah-Hartman]

On Fri, Jun 24, 2022 at 02:01:18AM +0000, Neal Liu wrote:
> > The bug is that we should still enter this loop if "tx_len" is zero.
> > 
> > Reported-by: Neal Liu <neal_liu@aspeedtech.com>
> > Fixes: c09b1f372e74 ("usb: gadget: aspeed_udc: cleanup loop in
> > ast_dma_descriptor_setup()")
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > ---
> > v2: Remove the unnecessary "chunk >= 0" condition
> 
> I mean v1 looks good to me.
> Sorry if you are misunderstanding.

I have no idea if v1 or v2 is the "correct" one here, sorry.

Dan, can you send a v3 that you all agree on?

thanks,

greg k-h