linux-kernel - Re: [PATCH v6 8/8] bus: mhi: core: Do not clear channel context more than once

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Message-ID: <e18295810c7ef7d2a0932f42351e542d@codeaurora.org>
Date:   Wed, 24 Feb 2021 10:55:17 -0800
From:   Bhaumik Bhatt <bbhatt@...eaurora.org>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc:     linux-arm-msm@...r.kernel.org, hemantk@...eaurora.org,
        jhugo@...eaurora.org, linux-kernel@...r.kernel.org,
        loic.poulain@...aro.org
Subject: Re: [PATCH v6 8/8] bus: mhi: core: Do not clear channel context more
 than once

On 2021-02-24 02:10 AM, Manivannan Sadhasivam wrote:
> On Thu, Feb 04, 2021 at 12:28:06PM -0800, Bhaumik Bhatt wrote:
>> Clearing a channel context can happen twice if the client driver
>> unprepares and reset the channels from the remove() callback from
>> a controller requested MHI power down sequence. If there are
>> multiple attempts at calling the mhi_free_coherent() API, we see
>> kernel warnings such as "trying to free invalid coherent area".
>> Example for one such client is the QRTR MHI driver. Avoid these
>> warnings by skipping mhi_deinit_chan_ctxt() API call and prevent
>> extra work from MHI as the channels are already disabled.
>> 
>> Signed-off-by: Bhaumik Bhatt <bbhatt@...eaurora.org>
> 
> Is this patch still valid? We merged a similar fix from Loic for v5.11.
> 
Yes, both the patches work to solve the same problem. This one just does 
it
sooner and relies on internal state variable rather than context being 
NULL.
> Thanks,
> Mani
> 
>> ---
>>  drivers/bus/mhi/core/init.c | 1 +
>>  1 file changed, 1 insertion(+)
>> 
>> diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
>> index 30eef19..272f350 100644
>> --- a/drivers/bus/mhi/core/init.c
>> +++ b/drivers/bus/mhi/core/init.c
>> @@ -1314,6 +1314,7 @@ static int mhi_driver_remove(struct device *dev)
>> 
>>  		if ((ch_state[dir] == MHI_CH_STATE_ENABLED ||
>>  		     ch_state[dir] == MHI_CH_STATE_STOP) &&
>> +		    mhi_chan->ch_state != MHI_CH_STATE_DISABLED &&
>>  		    !mhi_chan->offload_ch)
>>  			mhi_deinit_chan_ctxt(mhi_cntrl, mhi_chan);
>> 
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
>> Forum,
>> a Linux Foundation Collaborative Project
>> 

Thanks,
Bhaumik
---
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
Forum,
a Linux Foundation Collaborative Project