io_uring/zcrx: return error from io_zcrx_map_area_*

io_zcrx_map_area_*() helpers return the number of processed niovs, which
we use to unroll some of the mappings for user memory areas. It's
unhandy, and dmabuf doesn't care about it. Return an error code instead
and move failure partial unmapping into io_zcrx_map_area_umem().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: David Wei <dw@davidwei.uk>
Link: https://lore.kernel.org/r/42668e82be3a84b07ee8fc76d1d6d5ac0f137fe5.1751466461.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index e94a4647d409bcb300aa257d7a03bcef84a38bd6..6fb7c9bedfcb16f358055e950dadc708fc7c7815 100644 (file)
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -141,13 +141,13 @@ static int io_zcrx_map_area_dmabuf(struct io_zcrx_ifq *ifq, struct io_zcrx_area
                        struct net_iov *niov = &area->nia.niovs[niov_idx];
 
                        if (net_mp_niov_set_dma_addr(niov, dma))
-                               return 0;
+                               return -EFAULT;
                        sg_len -= PAGE_SIZE;
                        dma += PAGE_SIZE;
                        niov_idx++;
                }
        }
-       return niov_idx;
+       return 0;
 }
 
 static int io_import_umem(struct io_zcrx_ifq *ifq,
@@ -256,29 +256,30 @@ static int io_zcrx_map_area_umem(struct io_zcrx_ifq *ifq, struct io_zcrx_area *a
                        break;
                }
        }
-       return i;
+
+       if (i != area->nia.num_niovs) {
+               __io_zcrx_unmap_area(ifq, area, i);
+               return -EINVAL;
+       }
+       return 0;
 }
 
 static int io_zcrx_map_area(struct io_zcrx_ifq *ifq, struct io_zcrx_area *area)
 {
-       unsigned nr;
+       int ret;
 
        guard(mutex)(&ifq->dma_lock);
        if (area->is_mapped)
                return 0;
 
        if (area->mem.is_dmabuf)
-               nr = io_zcrx_map_area_dmabuf(ifq, area);
+               ret = io_zcrx_map_area_dmabuf(ifq, area);
        else
-               nr = io_zcrx_map_area_umem(ifq, area);
+               ret = io_zcrx_map_area_umem(ifq, area);
 
-       if (nr != area->nia.num_niovs) {
-               __io_zcrx_unmap_area(ifq, area, nr);
-               return -EINVAL;
-       }
-
-       area->is_mapped = true;
-       return 0;
+       if (ret == 0)
+               area->is_mapped = true;
+       return ret;
 }
 
 static void io_zcrx_sync_for_device(const struct page_pool *pool,