s390/pci_dma: improve debugging of errors during dma map

Improve debugging to find out what went wrong during a failed
dma map/unmap operation.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 30 insertions, 11 deletions

diff --git a/arch/s390/pci/pci_dma.c b/arch/s390/pci/pci_dma.c
index f137949c9abf..d348f2c09a1e 100644
--- a/arch/s390/pci/pci_dma.c
+++ b/arch/s390/pci/pci_dma.c
@@ -269,6 +269,16 @@ out:
         spin_unlock_irqrestore(&zdev->iommu_bitmap_lock, flags);
 }
 
+static inline void zpci_err_dma(unsigned long rc, unsigned long addr)
+{
+        struct {
+                unsigned long rc;
+                unsigned long addr;
+        } __packed data = {rc, addr};
+
+        zpci_err_hex(&data, sizeof(data));
+}
+
 static dma_addr_t s390_dma_map_pages(struct device *dev, struct page *page,
                                      unsigned long offset, size_t size,
                                      enum dma_data_direction direction,
@@ -279,33 +289,40 @@ static dma_addr_t s390_dma_map_pages(struct device *dev, struct page *page,
         unsigned long pa = page_to_phys(page) + offset;
         int flags = ZPCI_PTE_VALID;
         dma_addr_t dma_addr;
+        int ret;
 
         /* This rounds up number of pages based on size and offset */
         nr_pages = iommu_num_pages(pa, size, PAGE_SIZE);
         iommu_page_index = dma_alloc_iommu(zdev, nr_pages);
-        if (iommu_page_index == -1)
+        if (iommu_page_index == -1) {
+                ret = -ENOSPC;
                 goto out_err;
+        }
 
         /* Use rounded up size */
         size = nr_pages * PAGE_SIZE;
 
         dma_addr = zdev->start_dma + iommu_page_index * PAGE_SIZE;
-        if (dma_addr + size > zdev->end_dma)
+        if (dma_addr + size > zdev->end_dma) {
+                ret = -ERANGE;
                 goto out_free;
+        }
 
         if (direction == DMA_NONE || direction == DMA_TO_DEVICE)
                 flags |= ZPCI_TABLE_PROTECTED;
 
-        if (!dma_update_trans(zdev, pa, dma_addr, size, flags)) {
-                atomic64_add(nr_pages, &zdev->mapped_pages);
-                return dma_addr + (offset & ~PAGE_MASK);
-        }
+        ret = dma_update_trans(zdev, pa, dma_addr, size, flags);
+        if (ret)
+                goto out_free;
+
+        atomic64_add(nr_pages, &zdev->mapped_pages);
+        return dma_addr + (offset & ~PAGE_MASK);
 
 out_free:
         dma_free_iommu(zdev, iommu_page_index, nr_pages);
 out_err:
         zpci_err("map error:\n");
-        zpci_err_hex(&pa, sizeof(pa));
+        zpci_err_dma(ret, pa);
         return DMA_ERROR_CODE;
 }
 
@@ -315,14 +332,16 @@ static void s390_dma_unmap_pages(struct device *dev, dma_addr_t dma_addr,
 {
         struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
         unsigned long iommu_page_index;
-        int npages;
+        int npages, ret;
 
         npages = iommu_num_pages(dma_addr, size, PAGE_SIZE);
         dma_addr = dma_addr & PAGE_MASK;
-        if (dma_update_trans(zdev, 0, dma_addr, npages * PAGE_SIZE,
-                             ZPCI_PTE_INVALID)) {
+        ret = dma_update_trans(zdev, 0, dma_addr, npages * PAGE_SIZE,
+                               ZPCI_PTE_INVALID);
+        if (ret) {
                 zpci_err("unmap error:\n");
-                zpci_err_hex(&dma_addr, sizeof(dma_addr));
+                zpci_err_dma(ret, dma_addr);
+                return;
         }
 
         atomic64_add(npages, &zdev->unmapped_pages);