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    Subject[PATCH] usb: gadget: uvc: fix sg handling in error case
    Date
    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
    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)

    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");
    + queue->flags |= UVC_QUEUE_MISSED_XFER;
    + break;
    +
    case -ESHUTDOWN: /* disconnect from host. */
    uvcg_dbg(&video->uvc->func, "VS request cancelled.\n");
    uvcg_queue_cancel(queue, 1);
    --
    2.34.1
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