Re: [PATCH] net: qrtr: mhi: synchronize qrtr and mhi preparation

hemantk
2021-07-21T17:53:17Z

On 2021-07-20 18:42, Bhaumik Bhatt wrote:
> A dl callback can be received anytime after mhi_prepare_for_transfer
> has been called. There is a window where the callback may happen
> before the probe initializes the qrtr_mhi_dev state. Move the
> mhi_prepare_for_transfer call after the registering the endpoint.
>
> Once moved, the reverse can happen where qrtr will try to send a packet
> before the channels are prepared. Add a wait in the sending path to
> ensure the channels are prepared before trying to do a ul transfer.
>
> Fixes: a2e2cc0dbb11 ("net: qrtr: Start MHI channels during init")
> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
> ---
> net/qrtr/mhi.c | 20 +++++++++++++++-----
> 1 file changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c
> index 29b4fa3..22b0395 100644
> --- a/net/qrtr/mhi.c
> +++ b/net/qrtr/mhi.c
> @@ -15,6 +15,7 @@ struct qrtr_mhi_dev {
> struct qrtr_endpoint ep;
> struct mhi_device *mhi_dev;
> struct device *dev;
> + struct completion ready;
> };
>
> /* From MHI to QRTR */
> @@ -50,6 +51,10 @@ static int qcom_mhi_qrtr_send(struct qrtr_endpoint
> *ep, struct sk_buff *skb)
> struct qrtr_mhi_dev *qdev = container_of(ep, struct qrtr_mhi_dev,
> ep);
> int rc;
>
> + rc = wait_for_completion_interruptible(&qdev->ready);
> + if (rc)
> + goto free_skb;
> +
> if (skb->sk)
> sock_hold(skb->sk);
>
> @@ -78,11 +83,6 @@ static int qcom_mhi_qrtr_probe(struct mhi_device
> *mhi_dev,
> struct qrtr_mhi_dev *qdev;
> int rc;
>
> - /* start channels */
> - rc = mhi_prepare_for_transfer(mhi_dev, MHI_CH_INBOUND_ALLOC_BUFS);
> - if (rc)
> - return rc;
> -
> qdev = devm_kzalloc(&mhi_dev->dev, sizeof(*qdev), GFP_KERNEL);
> if (!qdev)
> return -ENOMEM;
would it be good to init completion variable here (call init_completion)
?
> @@ -90,12 +90,22 @@ static int qcom_mhi_qrtr_probe(struct mhi_device
> *mhi_dev,
> qdev->mhi_dev = mhi_dev;
> qdev->dev = &mhi_dev->dev;
> qdev->ep.xmit = qcom_mhi_qrtr_send;
> + init_completion(&qdev->ready);
>

>
> return 0;