svcrpc: ensure cache_check caller sees updated entry

[pandora-kernel.git] / net / sunrpc / cache.c

diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index a6c5733..72ad836 100644 (file)
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -128,6 +128,7 @@ static void cache_fresh_locked(struct cache_head *head, time_t expiry)
 {
        head->expiry_time = expiry;
        head->last_refresh = seconds_since_boot();
+       smp_wmb(); /* paired with smp_rmb() in cache_is_valid() */
        set_bit(CACHE_VALID, &head->flags);
 }
 
@@ -208,8 +209,16 @@ static inline int cache_is_valid(struct cache_detail *detail, struct cache_head
                /* entry is valid */
                if (test_bit(CACHE_NEGATIVE, &h->flags))
                        return -ENOENT;
-               else
+               else {
+                       /*
+                        * In combination with write barrier in
+                        * sunrpc_cache_update, ensures that anyone
+                        * using the cache entry after this sees the
+                        * updated contents:
+                        */
+                       smp_rmb();
                        return 0;
+               }
        }
 }