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From: "Michał Mirosław" <mirq-linux@rere.qmqm.pl>
To: Dmitry Osipenko <digetx@gmail.com>
Cc: Laxman Dewangan <ldewangan@nvidia.com>,
	Vinod Koul <vkoul@kernel.org>,
	Dan Williams <dan.j.williams@intel.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	dmaengine@vger.kernel.org, linux-tegra@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 3/7] dmaengine: tegra-apb: Prevent race conditions on channel's freeing
Date: Mon, 30 Dec 2019 21:45:55 +0100	[thread overview]
Message-ID: <20191230204555.GB24135@qmqm.qmqm.pl> (raw)
In-Reply-To: <20191228204640.25163-4-digetx@gmail.com>

On Sat, Dec 28, 2019 at 11:46:36PM +0300, Dmitry Osipenko wrote:
> It's unsafe to check the channel's "busy" state without taking a lock,
> it is also unsafe to assume that tasklet isn't in-fly.

'in-flight'. Also, the patch seems to have two independent bug-fixes
in it. Second one doesn't look right, at least not without an explanation.

First:

> -	if (tdc->busy)
> -		tegra_dma_terminate_all(dc);
> +	tegra_dma_terminate_all(dc);

Second:

> +	tasklet_kill(&tdc->tasklet);
>  
>  	spin_lock_irqsave(&tdc->lock, flags);
>  	list_splice_init(&tdc->pending_sg_req, &sg_req_list);
> @@ -1543,7 +1543,6 @@ static int tegra_dma_probe(struct platform_device *pdev)
>  		struct tegra_dma_channel *tdc = &tdma->channels[i];
>  
>  		free_irq(tdc->irq, tdc);
> -		tasklet_kill(&tdc->tasklet);
>  	}
>  
>  	pm_runtime_disable(&pdev->dev);
> @@ -1563,7 +1562,6 @@ static int tegra_dma_remove(struct platform_device *pdev)
>  	for (i = 0; i < tdma->chip_data->nr_channels; ++i) {
>  		tdc = &tdma->channels[i];
>  		free_irq(tdc->irq, tdc);
> -		tasklet_kill(&tdc->tasklet);
>  	}
>  
>  	pm_runtime_disable(&pdev->dev);

Best Regards,
Michał Mirosław

  reply	other threads:[~2019-12-30 20:46 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-28 20:46 [PATCH v1 0/7] NVIDIA Tegra APB DMA driver fixes and improvements Dmitry Osipenko
2019-12-28 20:46 ` [PATCH v1 1/7] dmaengine: tegra-apb: Fix use-after-free Dmitry Osipenko
2019-12-28 20:46 ` [PATCH v1 2/7] dmaengine: tegra-apb: Implement synchronization callback Dmitry Osipenko
2019-12-28 20:46 ` [PATCH v1 3/7] dmaengine: tegra-apb: Prevent race conditions on channel's freeing Dmitry Osipenko
2019-12-30 20:45   ` Michał Mirosław [this message]
2019-12-30 20:50     ` Michał Mirosław
2020-01-02 15:09       ` Dmitry Osipenko
2020-01-03  8:16         ` Michał Mirosław
2020-01-04  0:27           ` Dmitry Osipenko
2020-01-02 15:03     ` Dmitry Osipenko
2019-12-28 20:46 ` [PATCH v1 4/7] dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list Dmitry Osipenko
2019-12-28 20:46 ` [PATCH v1 5/7] dmaengine: tegra-apb: Use devm_platform_ioremap_resource Dmitry Osipenko
2019-12-28 20:46 ` [PATCH v1 6/7] dmaengine: tegra-apb: Use devm_request_irq Dmitry Osipenko
2019-12-28 20:46 ` [PATCH v1 7/7] dmaengine: tegra-apb: Fix coding style problems Dmitry Osipenko

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