svcrpc: avoid double reply caused by deferral race

[mv-sheeva.git] / net / sunrpc / cache.c

diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index e433e7580e27b221eff94d8b95ceaea703440618..0d6002f26d82313d25f142038a58e5fe926bb35b 100644 (file)
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -37,7 +37,7 @@
 
 #define         RPCDBG_FACILITY RPCDBG_CACHE
 
-static void cache_defer_req(struct cache_req *req, struct cache_head *item);
+static bool cache_defer_req(struct cache_req *req, struct cache_head *item);
 static void cache_revisit_request(struct cache_head *item);
 
 static void cache_init(struct cache_head *h)
@@ -268,9 +268,11 @@ int cache_check(struct cache_detail *detail,
        }
 
        if (rv == -EAGAIN) {
-               cache_defer_req(rqstp, h);
-               if (!test_bit(CACHE_PENDING, &h->flags)) {
-                       /* Request is not deferred */
+               if (!cache_defer_req(rqstp, h)) {
+                       /*
+                        * Request was not deferred; handle it as best
+                        * we can ourselves:
+                        */
                        rv = cache_is_valid(detail, h);
                        if (rv == -EAGAIN)
                                rv = -ETIMEDOUT;
@@ -618,18 +620,19 @@ static void cache_limit_defers(void)
                discard->revisit(discard, 1);
 }
 
-static void cache_defer_req(struct cache_req *req, struct cache_head *item)
+/* Return true if and only if a deferred request is queued. */
+static bool cache_defer_req(struct cache_req *req, struct cache_head *item)
 {
        struct cache_deferred_req *dreq;
 
        if (req->thread_wait) {
                cache_wait_req(req, item);
                if (!test_bit(CACHE_PENDING, &item->flags))
-                       return;
+                       return false;
        }
        dreq = req->defer(req);
        if (dreq == NULL)
-               return;
+               return false;
        setup_deferral(dreq, item, 1);
        if (!test_bit(CACHE_PENDING, &item->flags))
                /* Bit could have been cleared before we managed to
@@ -638,6 +641,7 @@ static void cache_defer_req(struct cache_req *req, struct cache_head *item)
                cache_revisit_request(item);
 
        cache_limit_defers();
+       return true;
 }
 
 static void cache_revisit_request(struct cache_head *item)