Re: PCI DMA to small buffers on cache-incoherent arch

From: Thunder from the hill (thunder@ngforever.de)
Date: Tue Jun 11 2002 - 18:00:51 EST

Hi,

On 11 Jun 2002, Roland Dreier wrote:
> 3) Change the code to
>
> struct something {
> int field1;
> char *dma_buffer;
> int field2;
> };
>
> struct something *dev = kmalloc(sizeof *dev, GFP_KERNEL);
> /* find pci_device */
> dev->dma_buffer = aligned_pci_alloc(pci_device, SMALLER_THAN_CACHELINE);
> /* do DMA into dev->dma_buffer */

You introduce a possible null pointer dereference here, don't you?

// Assume this fails:
struct something *dev = kmalloc(sizeof(struct something), GFP_KERNEL);
// dev is a NULL pointer now.
dev->dma_buffer = aligned_pci_alloc(pci_device, SMALLER_THAN_CACHELINE);
// Big bang

Just wondering...

Regards,
Thunder 

-- 
German attitude becoming        |	Thunder from the hill at ngforever
rightaway popular:		|
       "Get outa my way,  	|	free inhabitant not directly
    for I got a mobile phone!"	|	belonging anywhere

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

This archive was generated by hypermail 2b29 : Sat Jun 15 2002 - 22:00:23 EST