[PATCH v2 04/11] dmaengine: switchtec-dma: fix channel leak on registration failure

[Logan Gunthorpe <logang@deltatee.com>]

switchtec_dma_chans_release() is called in three places but the
underlying memory is not freed in all of those places. In order to
clean this up, introduce a switchtec_dma_chans_free() helper that
will free the memory.

Ensure each call to switchtec_dma_chans_release() has a corresponding
switchtec_dma_chans_free() call. (The release in switchtec_dma_remove()
pairs with the free in switchtec_dma_release()).

swdma_dev->chan_cnt is now set to the number of channels that succeeded
when one fails to initialise, so switchtec_dma_chans_free() can still
be used if not all channels succeed in being allocated.

Fixes: 30eba9df76ad ("dmaengine: switchtec-dma: Implement hardware initialization and cleanup")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Link: https://lore.kernel.org/dmaengine/20260717223024.9BB8A1F000E9@smtp.kernel.org
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
---
 drivers/dma/switchtec_dma.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/dma/switchtec_dma.c b/drivers/dma/switchtec_dma.c
index 107769cca772..13efd4189bbb 100644
--- a/drivers/dma/switchtec_dma.c
+++ b/drivers/dma/switchtec_dma.c
@@ -1176,6 +1176,16 @@ static int switchtec_dma_chans_release(struct pci_dev *pdev,
 	return 0;
 }
 
+static void switchtec_dma_chans_free(struct switchtec_dma_dev *swdma_dev)
+{
+	int i;
+
+	for (i = 0; i < swdma_dev->chan_cnt; i++)
+		kfree(swdma_dev->swdma_chans[i]);
+
+	kfree(swdma_dev->swdma_chans);
+}
+
 static int switchtec_dma_chans_enumerate(struct switchtec_dma_dev *swdma_dev,
 					 struct pci_dev *pdev, int chan_cnt)
 {
@@ -1201,7 +1211,7 @@ static int switchtec_dma_chans_enumerate(struct switchtec_dma_dev *swdma_dev,
 		if (rc) {
 			dev_err(&pdev->dev, "Channel %d: init channel failed\n",
 				i);
-			chan_cnt = i;
+			swdma_dev->chan_cnt = i;
 			goto err_exit;
 		}
 	}
@@ -1209,10 +1219,8 @@ static int switchtec_dma_chans_enumerate(struct switchtec_dma_dev *swdma_dev,
 	return chan_cnt;
 
 err_exit:
-	for (i = 0; i < chan_cnt; i++)
-		switchtec_dma_chan_free(pdev, swdma_dev->swdma_chans[i]);
-
-	kfree(swdma_dev->swdma_chans);
+	switchtec_dma_chans_release(pdev, swdma_dev);
+	switchtec_dma_chans_free(swdma_dev);
 
 	return rc;
 }
@@ -1221,12 +1229,8 @@ static void switchtec_dma_release(struct dma_device *dma_dev)
 {
 	struct switchtec_dma_dev *swdma_dev =
 		container_of(dma_dev, struct switchtec_dma_dev, dma_dev);
-	int i;
 
-	for (i = 0; i < swdma_dev->chan_cnt; i++)
-		kfree(swdma_dev->swdma_chans[i]);
-
-	kfree(swdma_dev->swdma_chans);
+	switchtec_dma_chans_free(swdma_dev);
 
 	put_device(dma_dev->dev);
 	kfree(swdma_dev);
@@ -1317,6 +1321,7 @@ static int switchtec_dma_create(struct pci_dev *pdev)
 
 err_chans_release_exit:
 	switchtec_dma_chans_release(pdev, swdma_dev);
+	switchtec_dma_chans_free(swdma_dev);
 
 err_exit:
 	if (swdma_dev->chan_status_irq)
-- 
2.47.3