On 11/7/2024 3:27 AM, Manivannan Sadhasivam 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>
I think we need to have the check in 'mhi_queue()' instead of waiting for the
channels in client drivers. Would it be a problem if qrtr returns -EAGAIN from
qcom_mhi_qrtr_send() instead of waiting for the channel?
The packet would get dropped which usually ends up causing some
functional problem down the line.
I can add retry handling for EAGAIN in qcom_mhi_qrtr_send().
Downstream we had also seen some issue where we received EAGAIN because
the ring buffer was full. I think we saw issues doing a dumb retry so we
triggered the retry on getting a ul_callback().
We would need to differentiate between this kind of EAGAIN from a
ringbuf full EAGAIN.
- Mani
---
net/qrtr/mhi.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c
index 69f53625a049..5b7268868bbd 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 prepared;
};
/* From MHI to QRTR */
@@ -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");
---
base-commit: 1ffec08567f426a1c593e038cadc61bdc38cb467
change-id: 20241104-qrtr_mhi-dfec353030af
Best regards,
--
Chris Lew <quic_clew@xxxxxxxxxxx>
