dmaengine: stm32: dmamux: fix OF node leak on route allocation failure

commit b1b590a upstream.

Make sure to drop the reference taken to the DMA master OF node also on
late route allocation failures.

Fixes: df7e762 ("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>
Link: https://patch.msgid.link/20251117161258.10679-12-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: jhovold

drivers/dma/stm32/stm32-dmamux.c

@@ -143,7 +143,7 @@ static void *stm32_dmamux_route_allocate(struct of_phandle_args *dma_spec,
 	ret = pm_runtime_resume_and_get(&pdev->dev);
 	if (ret < 0) {
 		spin_unlock_irqrestore(&dmamux->lock, flags);
-		goto error;
+		goto err_put_dma_spec_np;
 	}
 	spin_unlock_irqrestore(&dmamux->lock, flags);
 
@@ -165,6 +165,8 @@ static void *stm32_dmamux_route_allocate(struct of_phandle_args *dma_spec,
 
 	return mux;
 
+err_put_dma_spec_np:
+	of_node_put(dma_spec->np);
 error:
 	clear_bit(mux->chan_id, dmamux->dma_inuse);