Re: [PATCH 09/15] dmaengine: stm32: dmamux: fix device leak on route allocation

Amelie Delaunay
2025-11-18T08:12:14Z

On 11/17/25 17:12, 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: df7e762db5f6 ("dmaengine: Add STM32 DMAMUX driver")
> Cc: stable@vger.kernel.org # 4.15
> Cc: Pierre-Yves MORDRET <pierre-yves.mordret@foss.st.com>
> Signed-off-by: Johan Hovold <johan@kernel.org>

Reviewed-by: Amelie Delaunay <amelie.delaunay@foss.st.com>

> ---
> drivers/dma/stm32/stm32-dmamux.c | 18 ++++++++++++------
> 1 file changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/dma/stm32/stm32-dmamux.c b/drivers/dma/stm32/stm32-dmamux.c
> index 8d77e2a7939a..791179760782 100644
> --- a/drivers/dma/stm32/stm32-dmamux.c
> +++ b/drivers/dma/stm32/stm32-dmamux.c
> @@ -90,23 +90,25 @@ static void *stm32_dmamux_route_allocate(struct of_phandle_args *dma_spec,
> struct stm32_dmamux_data *dmamux = platform_get_drvdata(pdev);
> struct stm32_dmamux *mux;
> u32 i, min, max;
> - int ret;
> + int ret = -EINVAL;
> unsigned long flags;
>
> 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;
> }
>
> if (dma_spec->args[0] > dmamux->dmamux_requests) {
> dev_err(&pdev->dev, "invalid mux request number: %d\n",
> dma_spec->args[0]);
> - return ERR_PTR(-EINVAL);
> + goto err_put_pdev;
> }
>
> mux = kzalloc(sizeof(*mux), GFP_KERNEL);
> - if (!mux)
> - return ERR_PTR(-ENOMEM);
> + if (!mux) {
> + ret = -ENOMEM;
> + goto err_put_pdev;
> + }
>
> spin_lock_irqsave(&dmamux->lock, flags);
> mux->chan_id = find_first_zero_bit(dmamux->dma_inuse,
> @@ -133,7 +135,6 @@ static void *stm32_dmamux_route_allocate(struct of_phandle_args *dma_spec,
> dma_spec->np = of_parse_phandle(ofdma->of_node, "dma-masters", i - 1);
> if (!dma_spec->np) {
> dev_err(&pdev->dev, "can't get dma master\n");
> - ret = -EINVAL;
> goto error;
> }
>
> @@ -160,6 +161,8 @@ static void *stm32_dmamux_route_allocate(struct of_phandle_args *dma_spec,
> dev_dbg(&pdev->dev, "Mapping DMAMUX(%u) to DMA%u(%u)\n",
> mux->request, mux->master, mux->chan_id);
>
> + put_device(&pdev->dev);
> +
> return mux;
>
> error:
> @@ -167,6 +170,9 @@ static void *stm32_dmamux_route_allocate(struct of_phandle_args *dma_spec,
>
> error_chan_id:
> kfree(mux);
> +err_put_pdev:
> + put_device(&pdev->dev);
> +
> return ERR_PTR(ret);
> }
>