diff options
| -rw-r--r-- | drivers/block/xen-blkback/blkback.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c index 74374fb762aa..5ac841ff6cc7 100644 --- a/drivers/block/xen-blkback/blkback.c +++ b/drivers/block/xen-blkback/blkback.c @@ -161,10 +161,12 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif, static void make_response(struct xen_blkif *blkif, u64 id, unsigned short op, int st); -#define foreach_grant(pos, rbtree, node) \ - for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node); \ +#define foreach_grant_safe(pos, n, rbtree, node) \ + for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node), \ + (n) = rb_next(&(pos)->node); \ &(pos)->node != NULL; \ - (pos) = container_of(rb_next(&(pos)->node), typeof(*(pos)), node)) + (pos) = container_of(n, typeof(*(pos)), node), \ + (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL) static void add_persistent_gnt(struct rb_root *root, @@ -217,10 +219,11 @@ static void free_persistent_gnts(struct rb_root *root, unsigned int num) struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; struct persistent_gnt *persistent_gnt; + struct rb_node *n; int ret = 0; int segs_to_unmap = 0; - foreach_grant(persistent_gnt, root, node) { + foreach_grant_safe(persistent_gnt, n, root, node) { BUG_ON(persistent_gnt->handle == BLKBACK_INVALID_HANDLE); gnttab_set_unmap_op(&unmap[segs_to_unmap], @@ -230,9 +233,6 @@ static void free_persistent_gnts(struct rb_root *root, unsigned int num) persistent_gnt->handle); pages[segs_to_unmap] = persistent_gnt->page; - rb_erase(&persistent_gnt->node, root); - kfree(persistent_gnt); - num--; if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST || !rb_next(&persistent_gnt->node)) { @@ -241,6 +241,10 @@ static void free_persistent_gnts(struct rb_root *root, unsigned int num) BUG_ON(ret); segs_to_unmap = 0; } + + rb_erase(&persistent_gnt->node, root); + kfree(persistent_gnt); + num--; } BUG_ON(num != 0); } |