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xen-gntdev: Avoid unmapping ranges twice

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In paravirtualized domains, mn_invl_page or mn_invl_range_start can
unmap a segment of a mapped region without unmapping all pages. When
the region is later released, the pages will be unmapped twice, leading
to an incorrect -EINVAL return.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Daniel De Graaf 2011-02-09 15:12:00 -05:00 committed by Konrad Rzeszutek Wilk
parent 84e4075d60
commit b57c18694e
1 changed files with 31 additions and 2 deletions
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33
drivers/xen/gntdev.c
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@ -282,7 +282,7 @@ static int map_grant_pages(struct grant_map *map)
return err;
}
static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
{
int i, err = 0;
@ -301,7 +301,6 @@ static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
}
}
pr_debug("map %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset, pages);
if (err)
return err;
@ -314,6 +313,36 @@ static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
return err;
}
static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
{
int range, err = 0;
pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
/* It is possible the requested range will have a "hole" where we
* already unmapped some of the grants. Only unmap valid ranges.
*/
while (pages && !err) {
while (pages && !map->unmap_ops[offset].handle) {
offset++;
pages--;
}
range = 0;
while (range < pages) {
if (!map->unmap_ops[offset+range].handle) {
range--;
break;
}
range++;
}
err = __unmap_grant_pages(map, offset, range);
offset += range;
pages -= range;
}
return err;
}
/* ------------------------------------------------------------------ */
static void gntdev_vma_close(struct vm_area_struct *vma)