[PATCH v2 3/4] xen/blkback: simplify free_persistent_gnts() interface

[Juergen Gross <jgross@xxxxxxxx>]

The interface of free_persistent_gnts() can be simplified, as there is
only a single caller of free_persistent_gnts() and the 2nd and 3rd
parameters are easily obtainable via the ring pointer, which is passed
as the first parameter anyway.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 drivers/block/xen-blkback/blkback.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/block/xen-blkback/blkback.c 
b/drivers/block/xen-blkback/blkback.c
index 6e2163aaf362..243712b59a05 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -239,9 +239,9 @@ static void put_persistent_gnt(struct xen_blkif_ring *ring,
        atomic_dec(&ring->persistent_gnt_in_use);
 }
 
-static void free_persistent_gnts(struct xen_blkif_ring *ring, struct rb_root 
*root,
-                                 unsigned int num)
+static void free_persistent_gnts(struct xen_blkif_ring *ring)
 {
+       struct rb_root *root = &ring->persistent_gnts;
        struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
        struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
        struct persistent_gnt *persistent_gnt;
@@ -249,6 +249,9 @@ static void free_persistent_gnts(struct xen_blkif_ring 
*ring, struct rb_root *ro
        int segs_to_unmap = 0;
        struct gntab_unmap_queue_data unmap_data;
 
+       if (RB_EMPTY_ROOT(root))
+               return;
+
        unmap_data.pages = pages;
        unmap_data.unmap_ops = unmap;
        unmap_data.kunmap_ops = NULL;
@@ -277,9 +280,11 @@ static void free_persistent_gnts(struct xen_blkif_ring 
*ring, struct rb_root *ro
 
                rb_erase(&persistent_gnt->node, root);
                kfree(persistent_gnt);
-               num--;
+               ring->persistent_gnt_c--;
        }
-       BUG_ON(num != 0);
+
+       BUG_ON(!RB_EMPTY_ROOT(&ring->persistent_gnts));
+       BUG_ON(ring->persistent_gnt_c != 0);
 }
 
 void xen_blkbk_unmap_purged_grants(struct work_struct *work)
@@ -631,12 +636,7 @@ int xen_blkif_schedule(void *arg)
 void xen_blkbk_free_caches(struct xen_blkif_ring *ring)
 {
        /* Free all persistent grant pages */
-       if (!RB_EMPTY_ROOT(&ring->persistent_gnts))
-               free_persistent_gnts(ring, &ring->persistent_gnts,
-                       ring->persistent_gnt_c);
-
-       BUG_ON(!RB_EMPTY_ROOT(&ring->persistent_gnts));
-       ring->persistent_gnt_c = 0;
+       free_persistent_gnts(ring);
 
        /* Since we are shutting down remove all pages from the buffer */
        gnttab_page_cache_shrink(&ring->free_pages, 0 /* All */);
-- 
2.35.3