Re: [PATCH 06/15] dmaengine: lpc18xx-dmamux: fix device leak on route allocation

Vladimir Zapolskiy
2025-11-17T19:24:51Z

Hi Johan.

On 11/17/25 18:12, Johan Hovold wrote:
> Make sure to drop the reference taken when looking up the DMA mux
> platform device during route allocation.
>
> Note that holding a reference to a device does not prevent its driver
> data from going away so there is no point in keeping the reference.
>
> Fixes: e5f4ae84be74 ("dmaengine: add driver for lpc18xx dmamux")
> Cc: stable@vger.kernel.org # 4.3
> Signed-off-by: Johan Hovold <johan@kernel.org>
> ---
> drivers/dma/lpc18xx-dmamux.c | 19 ++++++++++++++-----
> 1 file changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/dma/lpc18xx-dmamux.c b/drivers/dma/lpc18xx-dmamux.c
> index 2b6436f4b193..d3ff521951b8 100644
> --- a/drivers/dma/lpc18xx-dmamux.c
> +++ b/drivers/dma/lpc18xx-dmamux.c
> @@ -57,30 +57,31 @@ static void *lpc18xx_dmamux_reserve(struct of_phandle_args *dma_spec,
> struct lpc18xx_dmamux_data *dmamux = platform_get_drvdata(pdev);
> unsigned long flags;
> unsigned mux;
> + int ret = -EINVAL;
>
> if (dma_spec->args_count != 3) {
> dev_err(&pdev->dev, "invalid number of dma mux args\n");
> - return ERR_PTR(-EINVAL);
> + goto err_put_pdev;
> }
>
> mux = dma_spec->args[0];
> if (mux >= dmamux->dma_master_requests) {
> dev_err(&pdev->dev, "invalid mux number: %d\n",
> dma_spec->args[0]);
> - return ERR_PTR(-EINVAL);
> + goto err_put_pdev;
> }
>
> if (dma_spec->args[1] > LPC18XX_DMAMUX_MAX_VAL) {
> dev_err(&pdev->dev, "invalid dma mux value: %d\n",
> dma_spec->args[1]);
> - return ERR_PTR(-EINVAL);
> + goto err_put_pdev;
> }
>
> /* The of_node_put() will be done in the core for the node */
> dma_spec->np = of_parse_phandle(ofdma->of_node, "dma-masters", 0);
> if (!dma_spec->np) {
> dev_err(&pdev->dev, "can't get dma master\n");
> - return ERR_PTR(-EINVAL);
> + goto err_put_pdev;
> }
>
> spin_lock_irqsave(&dmamux->lock, flags);
> @@ -89,7 +90,8 @@ static void *lpc18xx_dmamux_reserve(struct of_phandle_args *dma_spec,
> dev_err(&pdev->dev, "dma request %u busy with %u.%u\n",
> mux, mux, dmamux->muxes[mux].value);
> of_node_put(dma_spec->np);
> - return ERR_PTR(-EBUSY);
> + ret = -EBUSY;
> + goto err_put_pdev;
> }
>
> dmamux->muxes[mux].busy = true;
> @@ -106,7 +108,14 @@ static void *lpc18xx_dmamux_reserve(struct of_phandle_args *dma_spec,
> dev_dbg(&pdev->dev, "mapping dmamux %u.%u to dma request %u\n", mux,
> dmamux->muxes[mux].value, mux);
>
> + put_device(&pdev->dev);
> +
> return &dmamux->muxes[mux];
> +
> +err_put_pdev:
> + put_device(&pdev->dev);
> +
> + return ERR_PTR(ret);
> }
>
> static int lpc18xx_dmamux_probe(struct platform_device *pdev)

Reviewed-by: Vladimir Zapolskiy <vz@mleia.com>

--
Best wishes,
Vladimir