dmaengine: cv1800b-dmamux: fix device leak on route allocation

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: db7d07b ("dmaengine: add driver for Sophgo CV18XX/SG200X dmamux")
Cc: stable@vger.kernel.org	# 6.17
Cc: Inochi Amaoto <inochiama@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20251117161258.10679-5-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: jhovold

drivers/dma/cv1800b-dmamux.c

@@ -102,11 +102,11 @@ static void *cv1800_dmamux_route_allocate(struct of_phandle_args *dma_spec,
 	struct llist_node *node;
 	unsigned long flags;
 	unsigned int chid, devid, cpuid;
-	int ret;
+	int ret = -EINVAL;
 
 	if (dma_spec->args_count != DMAMUX_NCELLS) {
 		dev_err(&pdev->dev, "invalid number of dma mux args\n");
-		return ERR_PTR(-EINVAL);
+		goto err_put_pdev;
 	}
 
 	devid = dma_spec->args[0];
@@ -115,18 +115,18 @@ static void *cv1800_dmamux_route_allocate(struct of_phandle_args *dma_spec,
 
 	if (devid > MAX_DMA_MAPPING_ID) {
 		dev_err(&pdev->dev, "invalid device id: %u\n", devid);
-		return ERR_PTR(-EINVAL);
+		goto err_put_pdev;
 	}
 
 	if (cpuid > MAX_DMA_CPU_ID) {
 		dev_err(&pdev->dev, "invalid cpu id: %u\n", cpuid);
-		return ERR_PTR(-EINVAL);
+		goto err_put_pdev;
 	}
 
 	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);
@@ -136,8 +136,6 @@ static void *cv1800_dmamux_route_allocate(struct of_phandle_args *dma_spec,
 			if (map->peripheral == devid && map->cpu == cpuid)
 				goto found;
 		}
-
-		ret = -EINVAL;
 		goto failed;
 	} else {
 		node = llist_del_first(&dmamux->free_maps);
@@ -171,12 +169,17 @@ static void *cv1800_dmamux_route_allocate(struct of_phandle_args *dma_spec,
 	dev_dbg(&pdev->dev, "register channel %u for req %u (cpu %u)\n",
 		chid, devid, cpuid);
 
+	put_device(&pdev->dev);
+
 	return map;
 
 failed:
 	spin_unlock_irqrestore(&dmamux->lock, flags);
 	of_node_put(dma_spec->np);
 	dev_err(&pdev->dev, "errno %d\n", ret);
+err_put_pdev:
+	put_device(&pdev->dev);
+
 	return ERR_PTR(ret);
 }