Re: [PATCH v2 15/22] dma-direct: Support PCI P2PDMA pages in dma-direct map_sg
From: Christoph Hellwig <hch@lst.de>
Date: 2021-05-14 13:57:23
Also in:
linux-iommu, linux-mm, linux-nvme, linux-pci, lkml
+ for_each_sg(sgl, sg, nents, i) {
+ if (sg_is_dma_pci_p2pdma(sg)) {
+ sg_dma_unmark_pci_p2pdma(sg);
+ } else {Double space here. We also don't really need the curly braces to start with.
+ struct pci_p2pdma_map_state p2pdma_state = {};
+ enum pci_p2pdma_map_type map;
struct scatterlist *sg;
+ int i, ret;
for_each_sg(sgl, sg, nents, i) {
+ if (is_pci_p2pdma_page(sg_page(sg))) {
+ map = pci_p2pdma_map_segment(&p2pdma_state, dev, sg);
+ switch (map) {
Why not just:
switch (pci_p2pdma_map_segment(&p2pdma_state, dev,
sg)) {
(even better with a shorter name for p2pdma_state so that it all fits on
a single line)?
+ case PCI_P2PDMA_MAP_BUS_ADDR: + continue; + case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: + /* + * Mapping through host bridge should be + * mapped normally, thus we do nothing + * and continue below. + */
I have a bit of a hard time parsing this comment.
quoted hunk ↗ jump to hunk
+ if (sg->dma_address == DMA_MAPPING_ERROR) { + ret = -EINVAL; goto out_unmap; + } sg_dma_len(sg) = sg->length; }@@ -411,7 +443,7 @@ int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents, out_unmap: dma_direct_unmap_sg(dev, sgl, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC); - return -EINVAL; + return ret;
Maybe just initialize ret to -EINVAL at declaration time to simplify this a bit?