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

Robin Murphy
2018-01-10T17:02:36Z

On 10/01/18 15:46, Christoph Hellwig wrote:
> 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.

Yeah, only the assignment - as I said, it's just a stylistic nit; no big
deal either way.

>>> + 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.

Cool.

Robin.