[PATCH 4/4] dmaengine: ti: omap-dma: fix interrupt handling in remove

[Rosen Penev <rosenp@gmail.com>]

The remove path had three pre-existing bugs:

1. Interrupts are enabled via IRQENABLE_L1 in probe and alloc_chan_resources,
   but the remove path writes to IRQENABLE_L0, which has no effect on the L1
   interrupt line. The DMA engine can continue asserting its IRQ during
   removal. Write to IRQENABLE_L1 instead.

2. devm_free_irq() was called before disabling hardware interrupts. With
   IRQF_SHARED, the hardware may still assert the IRQ line after the handler
   is freed, causing unhandled interrupts that can lead to the kernel
   permanently disabling the shared IRQ line. Disable interrupts first.

3. platform_get_irq() return value was not checked before devm_free_irq().
   If it returns an error code (<= 0), passing it to devm_free_irq() is
   incorrect. Add a guard.

Fixes: 2e1136acf8a8 ("dmaengine: omap-dma: fix dma_pool resource leak in error paths")
Cc: stable@vger.kernel.org
Assisted-by: Opencode:BigPickle
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/dma/ti/omap-dma.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/ti/omap-dma.c b/drivers/dma/ti/omap-dma.c
index fd1ad3b4268c..ad90ca226db3 100644
--- a/drivers/dma/ti/omap-dma.c
+++ b/drivers/dma/ti/omap-dma.c
@@ -1859,16 +1859,17 @@ static void omap_dma_remove(struct platform_device *pdev)
 	if (pdev->dev.of_node)
 		of_dma_controller_free(pdev->dev.of_node);
 
-	irq = platform_get_irq(pdev, 1);
-	devm_free_irq(&pdev->dev, irq, od);
-
 	dma_async_device_unregister(&od->ddev);
 
 	if (!omap_dma_legacy(od)) {
-		/* Disable all interrupts */
-		omap_dma_glbl_write(od, IRQENABLE_L0, 0);
+		od->irq_enable_mask = 0;
+		omap_dma_glbl_write(od, IRQENABLE_L1, 0);
 	}
 
+	irq = platform_get_irq(pdev, 1);
+	if (irq > 0)
+		devm_free_irq(&pdev->dev, irq, od);
+
 	omap_dma_free(od);
 
 	if (od->ll123_supported)
-- 
2.54.0