xen-gntdev: Avoid unmapping ranges twice
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>
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@ -282,7 +282,7 @@ static int map_grant_pages(struct grant_map *map)
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return err;
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}
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static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
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static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
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{
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int i, err = 0;
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@ -301,7 +301,6 @@ static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
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}
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}
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pr_debug("map %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
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err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset, pages);
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if (err)
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return err;
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@ -314,6 +313,36 @@ static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
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return err;
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}
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static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
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{
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int range, err = 0;
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pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
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/* It is possible the requested range will have a "hole" where we
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* already unmapped some of the grants. Only unmap valid ranges.
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*/
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while (pages && !err) {
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while (pages && !map->unmap_ops[offset].handle) {
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offset++;
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pages--;
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}
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range = 0;
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while (range < pages) {
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if (!map->unmap_ops[offset+range].handle) {
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range--;
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break;
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}
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range++;
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}
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err = __unmap_grant_pages(map, offset, range);
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offset += range;
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pages -= range;
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}
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return err;
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}
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/* ------------------------------------------------------------------ */
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static void gntdev_vma_close(struct vm_area_struct *vma)
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