On 11/24/2024 7:04 AM, Manivannan Sadhasivam wrote:
On Thu, Nov 21, 2024 at 04:28:41PM -0800, Chris Lew wrote:
On 11/8/2024 2:32 AM, Johan Hovold wrote:
On Mon, Nov 04, 2024 at 05:29:37PM -0800, Chris Lew wrote:
From: Bhaumik Bhatt <bbhatt@xxxxxxxxxxxxxx>
The call to qrtr_endpoint_register() was moved before
mhi_prepare_for_transfer_autoqueue() to prevent a case where a dl
callback can occur before the qrtr endpoint is registered.
Now 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: 68a838b84eff ("net: qrtr: start MHI channel after endpoit creation")
Reported-by: Johan Hovold <johan@xxxxxxxxxx>
Closes: https://lore.kernel.org/linux-arm-msm/ZyTtVdkCCES0lkl4@xxxxxxxxxxxxxxxxxxxx/
Signed-off-by: Bhaumik Bhatt <bbhatt@xxxxxxxxxxxxxx>
Signed-off-by: Chris Lew <quic_clew@xxxxxxxxxxx>
@@ -53,6 +54,10 @@ static int qcom_mhi_qrtr_send(struct qrtr_endpoint *ep, struct sk_buff *skb)
if (skb->sk)
sock_hold(skb->sk);
+ rc = wait_for_completion_interruptible(&qdev->prepared);
+ if (rc)
+ goto free_skb;
+
rc = skb_linearize(skb);
if (rc)
goto free_skb;
@@ -85,6 +90,7 @@ 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->prepared);
dev_set_drvdata(&mhi_dev->dev, qdev);
rc = qrtr_endpoint_register(&qdev->ep, QRTR_EP_NID_AUTO);
@@ -97,6 +103,7 @@ static int qcom_mhi_qrtr_probe(struct mhi_device *mhi_dev,
qrtr_endpoint_unregister(&qdev->ep);
return rc;
}
+ complete_all(&qdev->prepared);
dev_dbg(qdev->dev, "Qualcomm MHI QRTR driver probed\n");
While this probably works, it still looks like a bit of a hack.
Why can't you restructure the code so that the channels are fully
initialised before you register or enable them instead?
Ok, I think we will have to stop using the autoqueue feature of MHI and
change the flow to be mhi_prepare_for_transfer() -->
qrtr_endpoint_register() --> mhi_queue_buf(DMA_FROM_DEVICE). This would make
it so ul_transfers only happen after mhi_prepare_for_transfer() and
dl_transfers happen after qrtr_endpoint_register().
I'll take a stab at implementing this.
Hmm, I thought 'autoqueue' was used for a specific reason. So it is not valid
now?
I think when MHI was being developed, I asked for an interface similar
to rpmsg. The team came up with the autoqueue feature which made the
qrtr mhi transport simpler and closer to the smd transport. I can't
think of a specific reason that QRTR needs autoqueue, but maybe ill find
it when I start poking at it.
- Mani
