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

Bhaumik Bhatt
2021-07-21T01:43:52Z

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;
@@ -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);

dev_set_drvdata(&mhi_dev->dev, qdev);
rc = qrtr_endpoint_register(&qdev->ep, QRTR_EP_NID_AUTO);
if (rc)
return rc;

+ /* start channels */
+ rc = mhi_prepare_for_transfer(mhi_dev, MHI_CH_INBOUND_ALLOC_BUFS);
+ if (rc) {
+ qrtr_endpoint_unregister(&qdev->ep);
+ dev_set_drvdata(&mhi_dev->dev, NULL);
+ return rc;
+ }
+
+ complete_all(&qdev->ready);
dev_dbg(qdev->dev, "Qualcomm MHI QRTR driver probed\n");

return 0;
--
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