Re: [PATCH v3 1/4] bus: mhi: host: Add spinlock to protect WP access when queueing TREs

[Manivannan Sadhasivam <mani@kernel.org>]

On Tue, Nov 07, 2023 at 03:16:02PM +0800, Qiang Yu wrote:
> From: Bhaumik Bhatt <bbhatt@codeaurora.org>
> 
> Protect WP accesses such that multiple threads queueing buffers for
> incoming data do not race.
> 
> Cc: <stable@vger.kernel.org>
> Fixes: 189ff97cca53 ("bus: mhi: core: Add support for data transfer")
> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
> Signed-off-by: Qiang Yu <quic_qianyu@quicinc.com>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

- Mani

> ---
>  drivers/bus/mhi/host/main.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
> index 6cf1145..c9415b0 100644
> --- a/drivers/bus/mhi/host/main.c
> +++ b/drivers/bus/mhi/host/main.c
> @@ -1205,6 +1205,9 @@ int mhi_gen_tre(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan,
>  	int eot, eob, chain, bei;
>  	int ret;
>  
> +	/* Protect accesses for reading and incrementing WP */
> +	write_lock_bh(&mhi_chan->lock);
> +
>  	buf_ring = &mhi_chan->buf_ring;
>  	tre_ring = &mhi_chan->tre_ring;
>  
> @@ -1222,8 +1225,10 @@ int mhi_gen_tre(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan,
>  
>  	if (!info->pre_mapped) {
>  		ret = mhi_cntrl->map_single(mhi_cntrl, buf_info);
> -		if (ret)
> +		if (ret) {
> +			write_unlock_bh(&mhi_chan->lock);
>  			return ret;
> +		}
>  	}
>  
>  	eob = !!(flags & MHI_EOB);
> @@ -1240,6 +1245,8 @@ int mhi_gen_tre(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan,
>  	mhi_add_ring_element(mhi_cntrl, tre_ring);
>  	mhi_add_ring_element(mhi_cntrl, buf_ring);
>  
> +	write_unlock_bh(&mhi_chan->lock);
> +
>  	return 0;
>  }
>  
> -- 
> 2.7.4
> 
> 

-- 
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