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Commit 77c35acb authored by Daniel De Graaf's avatar Daniel De Graaf Committed by Konrad Rzeszutek Wilk
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xen-gntdev: Fix incorrect use of zero handle 



The handle with numeric value 0 is a valid map handle, so it cannot
be used to indicate that a page has not been mapped. Use -1 instead.

Signed-off-by: default avatarDaniel De Graaf <dgdegra@tycho.nsa.gov>
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 1f169f66

drivers/xen/gntdev.c

+16 −7
Original line number Diff line number Diff line
@@ -126,6 +126,8 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count) 
		add->pages[i] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);

		if (add->pages[i] == NULL)

			goto err;

		add->map_ops[i].handle = -1;

		add->unmap_ops[i].handle = -1;

	}



	add->index = 0;
@@ -248,7 +250,7 @@ static int find_grant_ptes(pte_t *pte, pgtable_t token, 
			  map->grants[pgnr].ref,

			  map->grants[pgnr].domid);

	gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,

			    0 /* handle */);

			    -1 /* handle */);

	return 0;

}
@@ -259,7 +261,7 @@ static int map_grant_pages(struct grant_map *map) 


	if (!use_ptemod) {

		/* Note: it could already be mapped */

		if (map->map_ops[0].handle)

		if (map->map_ops[0].handle != -1)

			return 0;

		for (i = 0; i < map->count; i++) {

			addr = (phys_addr_t)
@@ -268,7 +270,7 @@ static int map_grant_pages(struct grant_map *map) 
				map->grants[i].ref,

				map->grants[i].domid);

			gnttab_set_unmap_op(&map->unmap_ops[i], addr,

				map->flags, 0 /* handle */);

				map->flags, -1 /* handle */);

		}

	}
@@ -280,7 +282,11 @@ static int map_grant_pages(struct grant_map *map) 
	for (i = 0; i < map->count; i++) {

		if (map->map_ops[i].status)

			err = -EINVAL;

		else {

			BUG_ON(map->map_ops[i].handle == -1);

			map->unmap_ops[i].handle = map->map_ops[i].handle;

			pr_debug("map handle=%d\n", map->map_ops[i].handle);

		}

	}

	return err;

}
@@ -313,7 +319,10 @@ static int __unmap_grant_pages(struct grant_map *map, int offset, int pages) 
	for (i = 0; i < pages; i++) {

		if (map->unmap_ops[offset+i].status)

			err = -EINVAL;

		map->unmap_ops[offset+i].handle = 0;

		pr_debug("unmap handle=%d st=%d\n",

			map->unmap_ops[offset+i].handle,

			map->unmap_ops[offset+i].status);

		map->unmap_ops[offset+i].handle = -1;

	}

	return err;

}
@@ -328,13 +337,13 @@ static int unmap_grant_pages(struct grant_map *map, int offset, int pages) 
	 * already unmapped some of the grants. Only unmap valid ranges.

	 */

	while (pages && !err) {

		while (pages && !map->unmap_ops[offset].handle) {

		while (pages && map->unmap_ops[offset].handle == -1) {

			offset++;

			pages--;

		}

		range = 0;

		while (range < pages) {

			if (!map->unmap_ops[offset+range].handle) {

			if (map->unmap_ops[offset+range].handle == -1) {

				range--;

				break;

			}