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); }