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Message-ID: <cd1da99a-e52e-e202-257d-17466132d088@nvidia.com>
Date: Wed, 29 Jan 2020 11:01:23 +0000
From: Jon Hunter <jonathanh@...dia.com>
To: Dmitry Osipenko <digetx@...il.com>,
Laxman Dewangan <ldewangan@...dia.com>,
Vinod Koul <vkoul@...nel.org>,
Dan Williams <dan.j.williams@...el.com>,
Thierry Reding <thierry.reding@...il.com>,
Michał Mirosław <mirq-linux@...e.qmqm.pl>
CC: <dmaengine@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 05/14] dmaengine: tegra-apb: Prevent race conditions of
tasklet vs free list
On 23/01/2020 23:03, Dmitry Osipenko wrote:
> The interrupt handler puts a half-completed DMA descriptor on a free list
> and then schedules tasklet to process bottom half of the descriptor that
> executes client's callback, this creates possibility to pick up the busy
> descriptor from the free list. Thus let's disallow descriptor's re-use
> until it is fully processed.
>
> Acked-by: Jon Hunter <jonathanh@...dia.com>
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
> drivers/dma/tegra20-apb-dma.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
> index 1b8a11804962..aafad50d075e 100644
> --- a/drivers/dma/tegra20-apb-dma.c
> +++ b/drivers/dma/tegra20-apb-dma.c
> @@ -281,7 +281,7 @@ static struct tegra_dma_desc *tegra_dma_desc_get(
>
> /* Do not allocate if desc are waiting for ack */
> list_for_each_entry(dma_desc, &tdc->free_dma_desc, node) {
> - if (async_tx_test_ack(&dma_desc->txd)) {
> + if (async_tx_test_ack(&dma_desc->txd) && !dma_desc->cb_count) {
> list_del(&dma_desc->node);
> spin_unlock_irqrestore(&tdc->lock, flags);
> dma_desc->txd.flags = 0;
>
I think we should mark this for stable as well. I would make this the
2nd patch in the series as it is related to #1.
Jon
--
nvpublic
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