Re: [PATCH 3/3] usb: ci_udc: verify all dtds are inactive before completing request

[Mattijs Korpershoek <mkorpershoek@kernel.org>]

Hi Ye,

Thank you for the patch.

On Fri, May 22, 2026 at 15:55, Ye Li <ye.li@nxp.com> wrote:

> From: Jason He <jason.he_1@nxp.com>
>
> According to device mode spec, the ACTIVE status field of dtds should
> be check to determine whether the transfers completed successfully.
> However, this is not implemented in handle_ep_complete.
> When two EPs are enabled and transferring, EPa requests with multiple dtds
> and EPb request with one dtd. Irq is triggred on EPb. The udc_irq handler
> finds both EPb's and EPa's ENDPTCOMPLETE=1 while not all of EPa's dtds
> have been completed. Because ACTIVE status is not checked, this case
> causes crash in ci_udc driver.
>
> Signed-off-by: Jason He <jason.he_1@nxp.com>
> Signed-off-by: Ye Li <ye.li@nxp.com>
> ---
>  drivers/usb/gadget/ci_udc.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/drivers/usb/gadget/ci_udc.c b/drivers/usb/gadget/ci_udc.c
> index 0baad83ef90..53796887dac 100644
> --- a/drivers/usb/gadget/ci_udc.c
> +++ b/drivers/usb/gadget/ci_udc.c
> @@ -733,6 +733,17 @@ static void handle_ep_complete(struct ci_ep *ci_ep)
>  	ci_invalidate_qtd(num);
>  	ci_req = list_first_entry(&ci_ep->queue, struct ci_req, queue);
>  
> +	/* Check all dtd are completed, otherwise return for next irq process */
> +	next_td = item;
> +	for (j = 0; j < ci_req->dtd_count; j++) {
> +		ci_invalidate_td(next_td);
> +		if (next_td->info & INFO_ACTIVE)
> +			return;
> +		if (j != ci_req->dtd_count - 1)
> +			next_td = (struct ept_queue_item *)(unsigned long)
> +				next_td->next;
> +	}

A very similar loop (that walks all the dtds) is just below:

> +
>  	next_td = item;
>  	len = 0;
>  	for (j = 0; j < ci_req->dtd_count; j++) {

Can't we merge both loops together?

> -- 
> 2.37.1