[media] media: ti-vpe: vpdma: Fix race condition for firmware loading

vpdma_create API is supposed to allocated the struct vpdma_data and
return it to the driver. Also, it would call the callback function
when the VPDMA firmware is loaded.

Typically, VPE driver have following function call:
    dev->vpdma = vpdma_create(pdev, firmware_load_callback);
And the callback implementation would continue the probe further.
Also, the dev->vpdma is accessed from the callback implementation.

This may lead to race condition between assignment of dev->vpdma
and the callback function being triggered.
This would lead to kernel crash because of NULL pointer access.

Fix this by passing a driver wrapped &vpdma_data instead of allocating
inside vpdma_create.
Change the vpdma_create prototype accordingly and fix return paths.

Also, update the VPE driver to use the updated API and
initialize the dev->vpdma before hand so that the race condition
is avoided.

Signed-off-by: Nikhil Devshatwar <nikhil.nd@ti.com>
Signed-off-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 5 insertions, 12 deletions

diff --git a/drivers/media/platform/ti-vpe/vpdma.c b/drivers/media/platform/ti-vpe/vpdma.c
index 8f0d608..070937f 100644
--- a/drivers/media/platform/ti-vpe/vpdma.c
+++ b/drivers/media/platform/ti-vpe/vpdma.c
@@ -1130,21 +1130,14 @@ static int vpdma_load_firmware(struct vpdma_data *vpdma)
 	return 0;
 }
 
-struct vpdma_data *vpdma_create(struct platform_device *pdev,
+int vpdma_create(struct platform_device *pdev, struct vpdma_data *vpdma,
 		void (*cb)(struct platform_device *pdev))
 {
 	struct resource *res;
-	struct vpdma_data *vpdma;
 	int r;
 
 	dev_dbg(&pdev->dev, "vpdma_create\n");
 
-	vpdma = devm_kzalloc(&pdev->dev, sizeof(*vpdma), GFP_KERNEL);
-	if (!vpdma) {
-		dev_err(&pdev->dev, "couldn't alloc vpdma_dev\n");
-		return ERR_PTR(-ENOMEM);
-	}
-
 	vpdma->pdev = pdev;
 	vpdma->cb = cb;
 	spin_lock_init(&vpdma->lock);
@@ -1152,22 +1145,22 @@ struct vpdma_data *vpdma_create(struct platform_device *pdev,
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "vpdma");
 	if (res == NULL) {
 		dev_err(&pdev->dev, "missing platform resources data\n");
-		return ERR_PTR(-ENODEV);
+		return -ENODEV;
 	}
 
 	vpdma->base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
 	if (!vpdma->base) {
 		dev_err(&pdev->dev, "failed to ioremap\n");
-		return ERR_PTR(-ENOMEM);
+		return -ENOMEM;
 	}
 
 	r = vpdma_load_firmware(vpdma);
 	if (r) {
 		pr_err("failed to load firmware %s\n", VPDMA_FIRMWARE);
-		return ERR_PTR(r);
+		return r;
 	}
 
-	return vpdma;
+	return 0;
 }
 EXPORT_SYMBOL(vpdma_create);