On Fri, Apr 21, 2023 at 06:06:39PM -0700, Brett Creeley wrote:
> +static int
> +pds_vfio_dma_map_lm_file(struct device *dev, enum dma_data_direction dir,
> + struct pds_vfio_lm_file *lm_file)
> +{
> + struct pds_lm_sg_elem *sgl, *sge;
> + struct scatterlist *sg;
> + dma_addr_t sgl_addr;
> + size_t sgl_size;
> + int err;
> + int i;
> +
> + if (!lm_file)
> + return -EINVAL;
> +
> + /* dma map file pages */
> + err = dma_map_sgtable(dev, &lm_file->sg_table, dir, 0);
> + if (err)
> + return err;
> +
> + lm_file->num_sge = lm_file->sg_table.nents;
> +
> + /* alloc sgl */
> + sgl_size = lm_file->num_sge * sizeof(struct pds_lm_sg_elem);
> + sgl = kzalloc(sgl_size, GFP_KERNEL);
> + if (!sgl) {
> + err = -ENOMEM;
> + goto err_alloc_sgl;
> + }
> +
> + sgl_addr = dma_map_single(dev, sgl, sgl_size, DMA_TO_DEVICE);
> + if (dma_mapping_error(dev, sgl_addr)) {
> + err = -EIO;
> + goto err_map_sgl;
> + }
> +
> + lm_file->sgl = sgl;
> + lm_file->sgl_addr = sgl_addr;
> +
> + /* fill sgl */
> + sge = sgl;
> + for_each_sgtable_dma_sg(&lm_file->sg_table, sg, i) {
> + sge->addr = cpu_to_le64(sg_dma_address(sg));
> + sge->len = cpu_to_le32(sg_dma_len(sg));
> + dev_dbg(dev, "addr = %llx, len = %u\n", sge->addr, sge->len);
> + sge++;
> + }
This sequence is in the wrong order, the dma_map_single() has to be
after the data is written to the memory as it synchronizes the caches
on some arches
> +
> + return 0;
> +
> +err_map_sgl:
> + kfree(sgl);
> +err_alloc_sgl:
> + dma_unmap_sgtable(dev, &lm_file->sg_table, dir, 0);
> + return err;
And why is the goto error unwind in a messed up order? Error unwinds
should always be strictly in the opposite order of the success
path. Check them all when you are fixing the "come from" notation
Jason
