Re: [PATCH] usb: gadget: uvc: fix sg handling in error case

On Mon, Sep 26, 2022 at 02:53:07PM -0500, Dan Vacura wrote:

If there is a transmission error the buffer will be returned too early, causing a memory fault as subsequent requests for that buffer are still queued up to be sent. Refactor the error handling to wait for the final request to come in before reporting back the buffer to userspace for all transfer types (bulk/isoc/isoc_sg) to ensure userspace knows if the frame was successfully sent.

Fixes: e81e7f9a0eb9 ("usb: gadget: uvc: add scatter gather support") Cc: stable@vger.kernel.org # 859c675d84d4: usb: gadget: uvc: consistently use define for headerlen Cc: stable@vger.kernel.org # f262ce66d40c: usb: gadget: uvc: use on returned header len in video_encode_isoc_sg Cc: stable@vger.kernel.org # 61aa709ca58a: usb: gadget: uvc: rework uvcg_queue_next_buffer to uvcg_complete_buffer Cc: stable@vger.kernel.org # 9b969f93bcef: usb: gadget: uvc: giveback vb2 buffer on req complete Cc: stable@vger.kernel.org # aef11279888c: usb: gadget: uvc: improve sg exit condition

I don't understand, why we backport all of these commits to 5.15.y if the original problem isn't in 5.15.y?

Or is it?

I'm confused,

greg k-h

Cc: stable@vger.kernel.org Signed-off-by: Dan Vacura w36195@motorola.com

---

drivers/usb/gadget/function/uvc_queue.c | 8 +++++--- drivers/usb/gadget/function/uvc_queue.h | 2 +- drivers/usb/gadget/function/uvc_video.c | 18 ++++++++++++++---- 3 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/gadget/function/uvc_queue.c b/drivers/usb/gadget/function/uvc_queue.c index ec500ee499ee..72e7ffd9a021 100644 --- a/drivers/usb/gadget/function/uvc_queue.c +++ b/drivers/usb/gadget/function/uvc_queue.c @@ -304,6 +304,7 @@ int uvcg_queue_enable(struct uvc_video_queue *queue, int enable) queue->sequence = 0; queue->buf_used = 0;

• queue->flags &= ~UVC_QUEUE_MISSED_XFER;
  

  } else { ret = vb2_streamoff(&queue->queue, queue->queue.type); if (ret < 0)

@@ -329,10 +330,11 @@ int uvcg_queue_enable(struct uvc_video_queue *queue, int enable) void uvcg_complete_buffer(struct uvc_video_queue *queue, struct uvc_buffer *buf) {

• if ((queue->flags & UVC_QUEUE_DROP_INCOMPLETE) &&

•     buf->length != buf->bytesused) {
  

• buf->state = UVC_BUF_STATE_QUEUED;
  

• if ((queue->flags & UVC_QUEUE_MISSED_XFER)) {

• queue->flags &= ~UVC_QUEUE_MISSED_XFER;
  

• buf->state = UVC_BUF_STATE_ERROR;
  

  vb2_set_plane_payload(&buf->buf.vb2_buf, 0, 0);

• vb2_buffer_done(&buf->buf.vb2_buf, VB2_BUF_STATE_ERROR);
  

  return; }

diff --git a/drivers/usb/gadget/function/uvc_queue.h b/drivers/usb/gadget/function/uvc_queue.h index 41f87b917f6b..741ec58ae9bb 100644 --- a/drivers/usb/gadget/function/uvc_queue.h +++ b/drivers/usb/gadget/function/uvc_queue.h @@ -42,7 +42,7 @@ struct uvc_buffer { }; #define UVC_QUEUE_DISCONNECTED (1 << 0) -#define UVC_QUEUE_DROP_INCOMPLETE (1 << 1) +#define UVC_QUEUE_MISSED_XFER (1 << 1)

Why change the name of the error?

struct uvc_video_queue { struct vb2_queue queue; diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/function/uvc_video.c index bb037fcc90e6..e46591b067a8 100644 --- a/drivers/usb/gadget/function/uvc_video.c +++ b/drivers/usb/gadget/function/uvc_video.c @@ -88,6 +88,7 @@ uvc_video_encode_bulk(struct usb_request *req, struct uvc_video *video, struct uvc_buffer *buf) { void *mem = req->buf;

• struct uvc_request *ureq = req->context; int len = video->req_size; int ret;

@@ -113,13 +114,14 @@ uvc_video_encode_bulk(struct usb_request *req, struct uvc_video *video, video->queue.buf_used = 0; buf->state = UVC_BUF_STATE_DONE; list_del(&buf->queue);

• uvcg_complete_buffer(&video->queue, buf);
  

  video->fid ^= UVC_STREAM_FID;

• ureq->last_buf = buf;
  

video->payload_size = 0; } if (video->payload_size == video->max_payload_size ||

•    video->queue.flags & UVC_QUEUE_MISSED_XFER ||
   buf->bytesused == video->queue.buf_used)
  

  video->payload_size = 0;

} @@ -180,7 +182,8 @@ uvc_video_encode_isoc_sg(struct usb_request *req, struct uvc_video *video, req->length -= len; video->queue.buf_used += req->length - header_len;

• if (buf->bytesused == video->queue.buf_used || !buf->sg) {

• if (buf->bytesused == video->queue.buf_used || !buf->sg ||

• 	video->queue.flags & UVC_QUEUE_MISSED_XFER) {
  

  video->queue.buf_used = 0; buf->state = UVC_BUF_STATE_DONE; buf->offset = 0;

@@ -195,6 +198,7 @@ uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video, struct uvc_buffer *buf) { void *mem = req->buf;

• struct uvc_request *ureq = req->context; int len = video->req_size; int ret;

@@ -209,12 +213,13 @@ uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video, req->length = video->req_size - len;

• if (buf->bytesused == video->queue.buf_used) {

• if (buf->bytesused == video->queue.buf_used ||

• 	video->queue.flags & UVC_QUEUE_MISSED_XFER) {
  

  video->queue.buf_used = 0; buf->state = UVC_BUF_STATE_DONE; list_del(&buf->queue);

• uvcg_complete_buffer(&video->queue, buf);
  

  video->fid ^= UVC_STREAM_FID;

• ureq->last_buf = buf;
  

  }

} @@ -255,6 +260,11 @@ uvc_video_complete(struct usb_ep *ep, struct usb_request *req) case 0: break;

• case -EXDEV:

• uvcg_info(&video->uvc->func, "VS request missed xfer.\n");
  

Why are you spamming the kernel logs at the info level for a USB transmission problem? That could get very noisy, please change this to be at the debug level.

thanks,

greg k-h