net: qrtr: start MHI channel after endpoit creation

MHI channel may generates event/interrupt right after enabling.
It may leads to 2 race conditions issues.

1)
Such event may be dropped by qcom_mhi_qrtr_dl_callback() at check:

	if (!qdev || mhi_res->transaction_status)
		return;

Because dev_set_drvdata(&mhi_dev->dev, qdev) may be not performed at
this moment. In this situation qrtr-ns will be unable to enumerate
services in device.
---------------------------------------------------------------

2)
Such event may come at the moment after dev_set_drvdata() and
before qrtr_endpoint_register(). In this case kernel will panic with
accessing wrong pointer at qcom_mhi_qrtr_dl_callback():

	rc = qrtr_endpoint_post(&qdev->ep, mhi_res->buf_addr,
				mhi_res->bytes_xferd);

Because endpoint is not created yet.
--------------------------------------------------------------
So move mhi_prepare_for_transfer_autoqueue after endpoint creation
to fix it.

Fixes: ce8f51e3e876 ("net: qrtr: Start MHI channels during init")
Signed-off-by: Maxim Kochetkov <fido_max@inbox.ru>
Reviewed-by: Hemant Kumar <quic_hemantk@quicinc.com>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c
index 18196e1c8c2fd2f303bb3eb3c93c8c18bb4e2fa0..9ced13c0627a7f7e6cac0c8532eeb4155b6b4e93 100644 (file)
--- a/net/qrtr/mhi.c
+++ b/net/qrtr/mhi.c
@@ -78,11 +78,6 @@ 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_autoqueue(mhi_dev);
-       if (rc)
-               return rc;
-
        qdev = devm_kzalloc(&mhi_dev->dev, sizeof(*qdev), GFP_KERNEL);
        if (!qdev)
                return -ENOMEM;
@@ -96,6 +91,13 @@ static int qcom_mhi_qrtr_probe(struct mhi_device *mhi_dev,
        if (rc)
                return rc;
 
+       /* start channels */
+       rc = mhi_prepare_for_transfer_autoqueue(mhi_dev);
+       if (rc) {
+               qrtr_endpoint_unregister(&qdev->ep);
+               return rc;
+       }
+
        dev_dbg(qdev->dev, "Qualcomm MHI QRTR driver probed\n");
 
        return 0;