Re: [RFC PATCH 1/1] s390/cio: make ccw_device_dma_* more robust
From: Pierre Morel
Date: Tue Oct 12 2021 - 10:11:17 EST
On 10/11/21 16:33, Cornelia Huck wrote:
On Mon, Oct 11 2021, Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:
On 10/11/21 1:59 PM, Halil Pasic wrote:
diff --git a/drivers/s390/cio/device_ops.c b/drivers/s390/cio/device_ops.c
index 0fe7b2f2e7f5..c533d1dadc6b 100644
--- a/drivers/s390/cio/device_ops.c
+++ b/drivers/s390/cio/device_ops.c
@@ -825,13 +825,23 @@ EXPORT_SYMBOL_GPL(ccw_device_get_chid);
*/
void *ccw_device_dma_zalloc(struct ccw_device *cdev, size_t size)
{
- return cio_gp_dma_zalloc(cdev->private->dma_pool, &cdev->dev, size);
+ void *addr;
+
+ if (!get_device(&cdev->dev))
+ return NULL;
+ addr = cio_gp_dma_zalloc(cdev->private->dma_pool, &cdev->dev, size);
+ if (IS_ERR_OR_NULL(addr))
I can be wrong but it seems that only dma_alloc_coherent() used in
cio_gp_dma_zalloc() report an error but the error is ignored and used as
a valid pointer.
Hm, I thought dma_alloc_coherent() returned either NULL or a valid
address?
hum, my bad, checked the wrong function, should have use my glasses or
connect my brain.
So shouldn't we modify this function and just test for a NULL address here?
If I read cio_gp_dma_zalloc() correctly, we either get NULL or a valid
address, so yes.
--
Pierre Morel
IBM Lab Boeblingen