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Subject: Re: [PATCH v4 03/14] dmaengine: tegra-apb: Prevent race conditions on
 channel's freeing
To:     Dmitry Osipenko <digetx@gmail.com>,
        Laxman Dewangan <ldewangan@nvidia.com>,
        Vinod Koul <vkoul@kernel.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        =?UTF-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= <mirq-linux@rere.qmqm.pl>
CC:     <dmaengine@vger.kernel.org>, <linux-tegra@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
References: <20200112173006.29863-1-digetx@gmail.com>
 <20200112173006.29863-4-digetx@gmail.com>
From:   Jon Hunter <jonathanh@nvidia.com>
Message-ID: <b99f455c-edd8-1a84-337a-fa0dc4ecb16a@nvidia.com>
Date:   Tue, 14 Jan 2020 15:16:45 +0000
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On 12/01/2020 17:29, Dmitry Osipenko wrote:
> It's incorrect to check the channel's "busy" state without taking a lock.
> That shouldn't cause any real troubles, nevertheless it's always better
> not to have any race conditions in the code.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/dma/tegra20-apb-dma.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
> index 664e9c5df3ba..24ad3a5a04e3 100644
> --- a/drivers/dma/tegra20-apb-dma.c
> +++ b/drivers/dma/tegra20-apb-dma.c
> @@ -1294,8 +1294,7 @@ static void tegra_dma_free_chan_resources(struct dma_chan *dc)
>  
>  	dev_dbg(tdc2dev(tdc), "Freeing channel %d\n", tdc->id);
>  
> -	if (tdc->busy)
> -		tegra_dma_terminate_all(dc);
> +	tegra_dma_terminate_all(dc);
>  
>  	spin_lock_irqsave(&tdc->lock, flags);
>  	list_splice_init(&tdc->pending_sg_req, &sg_req_list);

Acked-by: Jon Hunter <jonathanh@nvidia.com>

Cheers
Jon

-- 
nvpublic