'rs' is not used in that function. It's a leftover from commit
9360447d34 ("ram: Use MigrationStats for statistics").

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/ram.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/migration/ram.c b/migration/ram.c
index 9040d66e61..87efab72e8 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -561,7 +561,6 @@ void mig_throttle_counter_reset(void)
 /**
  * xbzrle_cache_zero_page: insert a zero page in the XBZRLE cache
  *
- * @rs: current RAM state
  * @current_addr: address for the zero page
  *
  * Update the xbzrle cache to reflect a page that's been sent as all 0.
@@ -570,7 +569,7 @@ void mig_throttle_counter_reset(void)
  * As a bonus, if the page wasn't in the cache it gets added so that
  * when a small write is made into the 0'd page it gets XBZRLE sent.
  */
-static void xbzrle_cache_zero_page(RAMState *rs, ram_addr_t current_addr)
+static void xbzrle_cache_zero_page(ram_addr_t current_addr)
 {
     /* We don't care if this fails to allocate a new cache page
      * as long as it updated an old one */
@@ -2148,7 +2147,7 @@ static int ram_save_target_page_legacy(RAMState *rs, PageSearchStatus *pss)
          */
         if (rs->xbzrle_started) {
             XBZRLE_cache_lock();
-            xbzrle_cache_zero_page(rs, block->offset + offset);
+            xbzrle_cache_zero_page(block->offset + offset);
             XBZRLE_cache_unlock();
         }
         return res;
-- 
2.35.3