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From: Manivannan Sadhasivam <mani@kernel.org>
To: Maxim Kochetkov <fido_max@inbox.ru>
Cc: mhi@lists.linux.dev, manivannan.sadhasivam@linaro.org,
	quic_hemantk@quicinc.com, bbhatt@codeaurora.org,
	Maxim Kochetkov <mkochetkov@airspan.com>
Subject: Re: [PATCH] net: qrtr: start MHI channel after endpoit creation
Date: Sat, 9 Jul 2022 11:38:57 +0530	[thread overview]
Message-ID: <20220709060857.GC5063@thinkpad> (raw)
In-Reply-To: <20220430103430.37349-1-fido_max@inbox.ru>

On Sat, Apr 30, 2022 at 01:34:30PM +0300, Maxim Kochetkov wrote:
> From: Maxim Kochetkov <mkochetkov@airspan.com>
> 
> 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: a2e2cc0dbb11 ("net: qrtr: Start MHI channels during init")
> Signed-off-by: Maxim Kochetkov <mkochetkov@airspan.com>

Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>

Thanks,
Mani

> ---
>  net/qrtr/mhi.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c
> index 18196e1c8c2f..17520d9e7a51 100644
> --- 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 +91,11 @@ 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)
> +		return rc;
> +
>  	dev_dbg(qdev->dev, "Qualcomm MHI QRTR driver probed\n");
>  
>  	return 0;
> -- 
> 2.34.1
> 

-- 
மணிவண்ணன் சதாசிவம்

      parent reply	other threads:[~2022-07-09  6:09 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-30 10:34 [PATCH] net: qrtr: start MHI channel after endpoit creation Maxim Kochetkov
2022-05-03  2:35 ` Hemant Kumar
2022-07-07  6:20   ` Maxim Kochetkov
2022-07-09  6:10     ` Manivannan Sadhasivam
2022-07-09  6:08 ` Manivannan Sadhasivam [this message]

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