Re: [PATCH 10/22] swiotlb: refactor coherent buffer allocation

Christoph Hellwig
2018-01-10T15:46:53Z

On Wed, Jan 10, 2018 at 12:22:18PM +0000, Robin Murphy wrote:
>> + if (phys_addr == SWIOTLB_MAP_ERROR)
>> + goto out_warn;
>> - /* Confirm address can be DMA'd by device */
>> - if (dev_addr + size - 1 > dma_mask) {
>> - printk("hwdev DMA mask = 0x%016Lx, dev_addr = 0x%016Lx\n",
>> - (unsigned long long)dma_mask,
>> - (unsigned long long)dev_addr);
>> + *dma_handle = swiotlb_phys_to_dma(dev, phys_addr);
>
> nit: this should probably go after the dma_coherent_ok() check (as with the
> original logic).

But the originall logic also needs the dma_addr_t for the
dma_coherent_ok check:

dev_addr = swiotlb_phys_to_dma(hwdev, paddr);
/* Confirm address can be DMA'd by device */
if (dev_addr + size - 1 > dma_mask) {
...
goto err_warn;
}

or do you mean assining to *dma_handle? The dma_handle is not
valid for a failure return, so I don't think this should matter.

>> + if (ret) {
>> + *dma_handle = swiotlb_virt_to_bus(hwdev, ret);
>> + if (dma_coherent_ok(hwdev, *dma_handle, size)) {
>> + memset(ret, 0, size);
>> + return ret;
>> + }
>
> Aren't we leaking the pages here?

Yes, that free_pages got lost somewhere in the rebases, I've added
it back.