[PATCH 3/7] gnttab: fold redundant error code paths in acquire_grant_for_copy()

One of the open-coded error paths of transitive grant handling is an exact
match of the code at the unlock_out_clear label. The other can be made so
by moving the put_page() earlier.

Signed-off-by: Jan Beulich <[email protected]>

--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -2729,10 +2729,7 @@ acquire_grant_for_copy(
         {
             atomic_dec(&rgt->nr_v2_ops);
             rcu_unlock_domain(td);
-            reduce_status_for_pin(rd, act, status, readonly);
-            active_entry_release(act);
-            grant_read_unlock(rgt);
-            return rc;
+            goto unlock_out_clear;
         }
 
         /*
@@ -2763,17 +2760,16 @@ acquire_grant_for_copy(
             release_grant_for_copy(td, trans_gref, readonly);
             rcu_unlock_domain(td);
 
+            put_page(*page);
+            *page = NULL;
+
             grant_read_lock(rgt);
             atomic_dec(&rgt->nr_v2_ops);
 
             act = active_entry_acquire(rgt, gref);
-            reduce_status_for_pin(rd, act, status, readonly);
-            active_entry_release(act);
-            grant_read_unlock(rgt);
 
-            put_page(*page);
-            *page = NULL;
-            return ERESTART;
+            rc = ERESTART;
+            goto unlock_out_clear;
         }
 
         if ( !old_pin )