linux-kernel - Re: [PATCH v3 3/4] bus: mhi: host: Avoid processing buffer and event of a disable channel

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Message-ID: <20231109163253.GL3752@thinkpad>
Date:   Thu, 9 Nov 2023 22:02:53 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Qiang Yu <quic_qianyu@...cinc.com>
Cc:     quic_jhugo@...cinc.com, mhi@...ts.linux.dev,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        quic_cang@...cinc.com, quic_mrana@...cinc.com
Subject: Re: [PATCH v3 3/4] bus: mhi: host: Avoid processing buffer and event
 of a disable channel

On Tue, Nov 07, 2023 at 03:16:04PM +0800, Qiang Yu wrote:
> Ckeck mhi channel state after getting chan->lock to ensure that we only
> queue buffer to an enabled channel and process event of an enabled channel.
> 

This commit message doesn't give proper explanation on how the channel can go to
disabled state in between parse_xfer_event() and mhi_gen_tre().

- Mani

> Signed-off-by: Qiang Yu <quic_qianyu@...cinc.com>
> ---
>  drivers/bus/mhi/host/main.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
> index a236dc2..b137d54 100644
> --- a/drivers/bus/mhi/host/main.c
> +++ b/drivers/bus/mhi/host/main.c
> @@ -672,6 +672,8 @@ static int parse_xfer_event(struct mhi_controller *mhi_cntrl,
>  			}
>  
>  			read_lock_bh(&mhi_chan->lock);
> +			if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED)
> +				goto end_process_tx_event;
>  		}
>  		break;
>  	} /* CC_EOT */
> @@ -1211,6 +1213,8 @@ int mhi_gen_tre(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan,
>  
>  	/* Protect accesses for reading and incrementing WP */
>  	write_lock_bh(&mhi_chan->lock);
> +	if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED)
> +		return -EINVAL;
>  
>  	buf_ring = &mhi_chan->buf_ring;
>  	tre_ring = &mhi_chan->tre_ring;
> -- 
> 2.7.4
> 
> 

-- 
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