[PATCH v2] drivers/dma/dma-jz4780: Fix race condition between probe and irq handler

[madhuparnabhowmik10]

From: Madhuparna Bhowmik <madhuparnabhowmi...@gmail.com>

In probe, IRQ is requested before zchan->id is initialized which can be
read in the irq handler. Hence, shift request irq after other initializations
complete.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmi...@gmail.com>

---
Changes since v1:
Keep enable clock before request IRQ.
---
 drivers/dma/dma-jz4780.c | 38 +++++++++++++++++++-------------------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c
index 448f663da89c..8beed91428bd 100644
--- a/drivers/dma/dma-jz4780.c
+++ b/drivers/dma/dma-jz4780.c
@@ -879,24 +879,11 @@ static int jz4780_dma_probe(struct platform_device *pdev)
                return -EINVAL;
        }
 
-       ret = platform_get_irq(pdev, 0);
-       if (ret < 0)
-               return ret;
-
-       jzdma->irq = ret;
-
-       ret = request_irq(jzdma->irq, jz4780_dma_irq_handler, 0, dev_name(dev),
-                         jzdma);
-       if (ret) {
-               dev_err(dev, "failed to request IRQ %u!\n", jzdma->irq);
-               return ret;
-       }
-
        jzdma->clk = devm_clk_get(dev, NULL);
        if (IS_ERR(jzdma->clk)) {
                dev_err(dev, "failed to get clock\n");
                ret = PTR_ERR(jzdma->clk);
-               goto err_free_irq;
+               return ret;
        }
 
        clk_prepare_enable(jzdma->clk);
@@ -949,10 +936,23 @@ static int jz4780_dma_probe(struct platform_device *pdev)
                jzchan->vchan.desc_free = jz4780_dma_desc_free;
        }
 
+       ret = platform_get_irq(pdev, 0);
+       if (ret < 0)
+               goto err_disable_clk;
+
+       jzdma->irq = ret;
+
+       ret = request_irq(jzdma->irq, jz4780_dma_irq_handler, 0, dev_name(dev),
+                         jzdma);
+       if (ret) {
+               dev_err(dev, "failed to request IRQ %u!\n", jzdma->irq);
+               goto err_disable_clk;
+       }
+
        ret = dmaenginem_async_device_register(dd);
        if (ret) {
                dev_err(dev, "failed to register device\n");
-               goto err_disable_clk;
+               goto err_free_irq;
        }
 
        /* Register with OF DMA helpers. */
@@ -960,17 +960,17 @@ static int jz4780_dma_probe(struct platform_device *pdev)
                                         jzdma);
        if (ret) {
                dev_err(dev, "failed to register OF DMA controller\n");
-               goto err_disable_clk;
+               goto err_free_irq;
        }
 
        dev_info(dev, "JZ4780 DMA controller initialised\n");
        return 0;
 
-err_disable_clk:
-       clk_disable_unprepare(jzdma->clk);
-
 err_free_irq:
        free_irq(jzdma->irq, jzdma);
+
+err_disable_clk:
+       clk_disable_unprepare(jzdma->clk);
        return ret;
 }
 
-- 
2.17.1