dma: use ERROR_INT()

The first in a series excising the use of the "return -errno" idiom. This is a
non-standard usage, and in userspace, we have "errno" for delivering side-band
error values. As there have been multiple bugs from not using standard error
return methods like -1+errno or NULL+errno, let's do that.

Signed-off-by: John Levon <john.levon@nutanix.com>
Reviewed-by: Thanos Makatos <thanos.makatos@nutanix.com>

1 files changed, 13 insertions, 6 deletions

diff --git a/lib/libvfio-user.c b/lib/libvfio-user.c
index 0440351..f4aa804 100644
--- a/lib/libvfio-user.c
+++ b/lib/libvfio-user.c
@@ -532,11 +532,12 @@ handle_dma_map_or_unmap(vfu_ctx_t *vfu_ctx, uint32_t size, bool map,
                                             region->size, fd, region->offset,
                                             region->prot);
             if (ret < 0) {
+                ret = -errno;
+                vfu_log(vfu_ctx, LOG_ERR, "failed to add DMA region %s: %m",
+                        rstr);
                 if (fd != -1) {
                     close(fd);
                 }
-                vfu_log(vfu_ctx, LOG_ERR, "failed to add DMA region %s: %s",
-                        rstr, strerror(-ret));
                 break;
             }
 
@@ -553,8 +554,9 @@ handle_dma_map_or_unmap(vfu_ctx_t *vfu_ctx, uint32_t size, bool map,
                                                vfu_ctx->dma_unregister,
                                                vfu_ctx);
             if (ret < 0) {
-                vfu_log(vfu_ctx, LOG_ERR, "failed to remove DMA region %s: %s",
-                        rstr, strerror(-ret));
+                ret = -errno;
+                vfu_log(vfu_ctx, LOG_ERR, "failed to remove DMA region %s: %m",
+                        rstr);
                 break;
             }
         }
@@ -603,6 +605,7 @@ handle_dirty_pages_get(vfu_ctx_t *vfu_ctx,
                                             r->bitmap.size,
                                             (char**)&((*iovecs)[i].iov_base));
         if (ret != 0) {
+            ret = -errno;
             goto out;
         }
         (*iovecs)[i].iov_len = r->bitmap.size;
@@ -637,8 +640,12 @@ MOCK_DEFINE(handle_dirty_pages)(vfu_ctx_t *vfu_ctx, uint32_t size,
     if (dirty_bitmap->flags & VFIO_IOMMU_DIRTY_PAGES_FLAG_START) {
         ret = dma_controller_dirty_page_logging_start(vfu_ctx->dma,
                                                       migration_get_pgsize(vfu_ctx->migration));
+        if (ret == -1) {
+            ret = -errno;
+        }
     } else if (dirty_bitmap->flags & VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP) {
-        ret = dma_controller_dirty_page_logging_stop(vfu_ctx->dma);
+        dma_controller_dirty_page_logging_stop(vfu_ctx->dma);
+        ret = 0;
     } else if (dirty_bitmap->flags & VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP) {
         ret = handle_dirty_pages_get(vfu_ctx, iovecs, nr_iovecs,
                                      (struct vfio_iommu_type1_dirty_bitmap_get*)(dirty_bitmap + 1),
@@ -1520,7 +1527,7 @@ vfu_map_sg(vfu_ctx_t *vfu_ctx, const dma_sg_t *sg,
 
     ret = dma_map_sg(vfu_ctx->dma, sg, iov, cnt);
     if (ret < 0) {
-        return ERROR_INT(-ret);
+        return -1;
     }
 
     return 0;