[PATCH v4 12/17] xen: mapcache: Unmap first entries in buckets

["Edgar E. Iglesias" <edgar.iglesias@xxxxxxxxx>]

From: "Edgar E. Iglesias" <edgar.iglesias@xxxxxxx>

When invalidating memory ranges, if we happen to hit the first
entry in a bucket we were never unmapping it. This was harmless
for foreign mappings but now that we're looking to reuse the
mapcache for transient grant mappings, we must unmap entries
when invalidated.

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xxxxxxx>
---
 hw/xen/xen-mapcache.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/hw/xen/xen-mapcache.c b/hw/xen/xen-mapcache.c
index 4f98d284dd..0365311788 100644
--- a/hw/xen/xen-mapcache.c
+++ b/hw/xen/xen-mapcache.c
@@ -486,18 +486,22 @@ static void 
xen_invalidate_map_cache_entry_unlocked(MapCache *mc,
         return;
     }
     entry->lock--;
-    if (entry->lock > 0 || pentry == NULL) {
+    if (entry->lock > 0) {
         return;
     }
 
-    pentry->next = entry->next;
     ram_block_notify_remove(entry->vaddr_base, entry->size, entry->size);
     if (munmap(entry->vaddr_base, entry->size) != 0) {
         perror("unmap fails");
         exit(-1);
     }
-    g_free(entry->valid_mapping);
-    g_free(entry);
+    if (pentry) {
+        pentry->next = entry->next;
+        g_free(entry->valid_mapping);
+        g_free(entry);
+    } else {
+        memset(entry, 0, sizeof *entry);
+    }
 }
 
 typedef struct XenMapCacheData {
-- 
2.40.1