xen-front-pgdir-shbuf: don't record wrong grant handle upon error

In order for subsequent unmapping to not mistakenly unmap handle 0,
record a perceived always-invalid one instead.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Link: https://lore.kernel.org/r/82414b0f-1b63-5509-7c1d-5bcc8239a3de@suse.com
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

diff --git a/drivers/xen/xen-front-pgdir-shbuf.c b/drivers/xen/xen-front-pgdir-shbuf.c
index 48a658d..81b6e13 100644 (file)
--- a/drivers/xen/xen-front-pgdir-shbuf.c
+++ b/drivers/xen/xen-front-pgdir-shbuf.c
@@ -305,11 +305,18 @@ static int backend_map(struct xen_front_pgdir_shbuf *buf)
 
        /* Save handles even if error, so we can unmap. */
        for (cur_page = 0; cur_page < buf->num_pages; cur_page++) {
-               buf->backend_map_handles[cur_page] = map_ops[cur_page].handle;
-               if (unlikely(map_ops[cur_page].status != GNTST_okay))
+               if (likely(map_ops[cur_page].status == GNTST_okay)) {
+                       buf->backend_map_handles[cur_page] =
+                               map_ops[cur_page].handle;
+               } else {
+                       buf->backend_map_handles[cur_page] =
+                               INVALID_GRANT_HANDLE;
+                       if (!ret)
+                               ret = -ENXIO;
                        dev_err(&buf->xb_dev->dev,
                                "Failed to map page %d: %d\n",
                                cur_page, map_ops[cur_page].status);
+               }
        }
 
        if (ret) {