[Xen-devel] [RFC PATCH 30/60] hyper_dmabuf: free already mapped pages when error happens

[Dongwon Kim <dongwon.kim@xxxxxxxxx>]

From: Mateusz Polrola <mateuszx.potrola@xxxxxxxxx>

It is needed to freeing already-mapped pages if it gets error
before finishing mapping all pages.

Signed-off-by: Dongwon Kim <dongwon.kim@xxxxxxxxx>
---
 .../xen/hyper_dmabuf/xen/hyper_dmabuf_xen_shm.c    | 43 +++++++++++++++++++---
 1 file changed, 38 insertions(+), 5 deletions(-)

diff --git a/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_shm.c 
b/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_shm.c
index c03e5a0..524f75c 100644
--- a/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_shm.c
+++ b/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_shm.c
@@ -255,7 +255,7 @@ struct page ** hyper_dmabuf_xen_map_shared_pages(int 
lvl3_gref, int domid, int n
        if (lvl3_map_ops.status) {
                dev_err(hyper_dmabuf_private.device, "HYPERVISOR map grant ref 
failed status = %d",
                        lvl3_map_ops.status);
-               return NULL;
+               goto error_cleanup_lvl3;
        } else {
                lvl3_unmap_ops.handle = lvl3_map_ops.handle;
        }
@@ -263,7 +263,7 @@ struct page ** hyper_dmabuf_xen_map_shared_pages(int 
lvl3_gref, int domid, int n
        /* Map all second level pages */
        if (gnttab_alloc_pages(n_lvl2_grefs, lvl2_table_pages)) {
                dev_err(hyper_dmabuf_private.device, "Cannot allocate pages\n");
-               return NULL;
+               goto error_cleanup_lvl3;
        }
 
        for (i = 0; i < n_lvl2_grefs; i++) {
@@ -277,6 +277,9 @@ struct page ** hyper_dmabuf_xen_map_shared_pages(int 
lvl3_gref, int domid, int n
        if (gnttab_unmap_refs(&lvl3_unmap_ops, NULL, &lvl3_table_page, 1)) {
                dev_err(hyper_dmabuf_private.device, "xen: cannot unmap top 
level page\n");
                return NULL;
+       } else {
+               /* Mark that page was unmapped */
+               lvl3_unmap_ops.handle = -1;
        }
 
        if (gnttab_map_refs(lvl2_map_ops, NULL, lvl2_table_pages, 
n_lvl2_grefs)) {
@@ -290,7 +293,7 @@ struct page ** hyper_dmabuf_xen_map_shared_pages(int 
lvl3_gref, int domid, int n
                        dev_err(hyper_dmabuf_private.device,
                                "HYPERVISOR map grant ref failed status = %d",
                                lvl2_map_ops[i].status);
-                       return NULL;
+                       goto error_cleanup_lvl2;
                } else {
                        lvl2_unmap_ops[i].handle = lvl2_map_ops[i].handle;
                }
@@ -298,7 +301,7 @@ struct page ** hyper_dmabuf_xen_map_shared_pages(int 
lvl3_gref, int domid, int n
 
        if (gnttab_alloc_pages(nents, data_pages)) {
                dev_err(hyper_dmabuf_private.device, "Cannot allocate pages\n");
-               return NULL;
+               goto error_cleanup_lvl2;
        }
 
        k = 0;
@@ -343,6 +346,11 @@ struct page ** hyper_dmabuf_xen_map_shared_pages(int 
lvl3_gref, int domid, int n
                              n_lvl2_grefs)) {
                dev_err(hyper_dmabuf_private.device, "Cannot unmap 2nd level 
refs\n");
                return NULL;
+       } else {
+               /* Mark that pages were unmapped */
+               for (i = 0; i < n_lvl2_grefs; i++) {
+                       lvl2_unmap_ops[i].handle = -1;
+               }
        }
 
        for (i = 0; i < nents; i++) {
@@ -350,7 +358,7 @@ struct page ** hyper_dmabuf_xen_map_shared_pages(int 
lvl3_gref, int domid, int n
                        dev_err(hyper_dmabuf_private.device,
                                "HYPERVISOR map grant ref failed status = %d\n",
                                data_map_ops[i].status);
-                       return NULL;
+                       goto error_cleanup_data;
                } else {
                        data_unmap_ops[i].handle = data_map_ops[i].handle;
                }
@@ -369,6 +377,31 @@ struct page ** hyper_dmabuf_xen_map_shared_pages(int 
lvl3_gref, int domid, int n
 
        dev_dbg(hyper_dmabuf_private.device, "%s exit\n", __func__);
        return data_pages;
+
+error_cleanup_data:
+       gnttab_unmap_refs(data_unmap_ops, NULL, data_pages,
+                         nents);
+
+       gnttab_free_pages(nents, data_pages);
+
+error_cleanup_lvl2:
+       if (lvl2_unmap_ops[0].handle != -1)
+               gnttab_unmap_refs(lvl2_unmap_ops, NULL, lvl2_table_pages,
+                                 n_lvl2_grefs);
+       gnttab_free_pages(n_lvl2_grefs, lvl2_table_pages);
+
+error_cleanup_lvl3:
+       if (lvl3_unmap_ops.handle != -1)
+               gnttab_unmap_refs(&lvl3_unmap_ops, NULL, &lvl3_table_page, 1);
+       gnttab_free_pages(1, &lvl3_table_page);
+
+       kfree(lvl2_table_pages);
+       kfree(lvl2_map_ops);
+       kfree(lvl2_unmap_ops);
+       kfree(data_map_ops);
+
+
+       return NULL;
 }
 
 int hyper_dmabuf_xen_unmap_shared_pages(void **refs_info, int nents) {
-- 
2.7.4


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