static void alpha_pci_unmap_sg()

in kernel/pci_iommu.c [713:787]

• 55 lines of code
• 14 McCabe index (conditional complexity)

static void alpha_pci_unmap_sg(struct device *dev, struct scatterlist *sg,
			       int nents, enum dma_data_direction dir,
			       unsigned long attrs)
{
	struct pci_dev *pdev = alpha_gendev_to_pci(dev);
	unsigned long flags;
	struct pci_controller *hose;
	struct pci_iommu_arena *arena;
	struct scatterlist *end;
	dma_addr_t max_dma;
	dma_addr_t fbeg, fend;

	BUG_ON(dir == PCI_DMA_NONE);

	if (! alpha_mv.mv_pci_tbi)
		return;

	hose = pdev ? pdev->sysdata : pci_isa_hose;
	max_dma = pdev ? pdev->dma_mask : ISA_DMA_MASK;
	arena = hose->sg_pci;
	if (!arena || arena->dma_base + arena->size - 1 > max_dma)
		arena = hose->sg_isa;

	fbeg = -1, fend = 0;

	spin_lock_irqsave(&arena->lock, flags);

	for (end = sg + nents; sg < end; ++sg) {
		dma_addr_t addr;
		size_t size;
		long npages, ofs;
		dma_addr_t tend;

		addr = sg->dma_address;
		size = sg->dma_length;
		if (!size)
			break;

		if (addr > 0xffffffff) {
			/* It's a DAC address -- nothing to do.  */
			DBGA("    (%ld) DAC [%llx,%zx]\n",
			      sg - end + nents, addr, size);
			continue;
		}

		if (addr >= __direct_map_base
		    && addr < __direct_map_base + __direct_map_size) {
			/* Nothing to do.  */
			DBGA("    (%ld) direct [%llx,%zx]\n",
			      sg - end + nents, addr, size);
			continue;
		}

		DBGA("    (%ld) sg [%llx,%zx]\n",
		     sg - end + nents, addr, size);

		npages = iommu_num_pages(addr, size, PAGE_SIZE);
		ofs = (addr - arena->dma_base) >> PAGE_SHIFT;
		iommu_arena_free(arena, ofs, npages);

		tend = addr + size - 1;
		if (fbeg > addr) fbeg = addr;
		if (fend < tend) fend = tend;
	}

        /* If we're freeing ptes above the `next_entry' pointer (they
           may have snuck back into the TLB since the last wrap flush),
           we need to flush the TLB before reallocating the latter.  */
	if ((fend - arena->dma_base) >> PAGE_SHIFT >= arena->next_entry)
		alpha_mv.mv_pci_tbi(hose, fbeg, fend);

	spin_unlock_irqrestore(&arena->lock, flags);

	DBGA("pci_unmap_sg: %ld entries\n", nents - (end - sg));
}