2 files changed, 20 insertions, 7 deletions

diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 3435d24bfe55..39ec186a492d 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -41,6 +41,7 @@ struct svc_pool {
         struct list_head        sp_sockets;     /* pending sockets */
         unsigned int            sp_nrthreads;   /* # of threads in pool */
         struct list_head        sp_all_threads; /* all server threads */
+        int                     sp_nwaking;     /* number of threads woken but not yet active */
 } ____cacheline_aligned_in_smp;
 
 /*
@@ -264,6 +265,7 @@ struct svc_rqst {
                                                  * cache pages */
         wait_queue_head_t       rq_wait;        /* synchronization */
         struct task_struct      *rq_task;       /* service thread */
+        int                     rq_waking;      /* 1 if thread is being woken */
 };
 
 /*
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index e588df5d6b34..0551b6b6cf8c 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -14,6 +14,8 @@
 
 #define RPCDBG_FACILITY RPCDBG_SVCXPRT
 
+#define SVC_MAX_WAKING 5
+
 static struct svc_deferred_req *svc_deferred_dequeue(struct svc_xprt *xprt);
 static int svc_deferred_recv(struct svc_rqst *rqstp);
 static struct cache_deferred_req *svc_defer(struct cache_req *req);
@@ -298,6 +300,7 @@ void svc_xprt_enqueue(struct svc_xprt *xprt)
         struct svc_pool *pool;
         struct svc_rqst *rqstp;
         int cpu;
+        int thread_avail;
 
         if (!(xprt->xpt_flags &
               ((1<<XPT_CONN)|(1<<XPT_DATA)|(1<<XPT_CLOSE)|(1<<XPT_DEFERRED))))
@@ -309,12 +312,6 @@ void svc_xprt_enqueue(struct svc_xprt *xprt)
 
         spin_lock_bh(&pool->sp_lock);
 
-        if (!list_empty(&pool->sp_threads) &&
-            !list_empty(&pool->sp_sockets))
-                printk(KERN_ERR
-                       "svc_xprt_enqueue: "
-                       "threads and transports both waiting??\n");
-
         if (test_bit(XPT_DEAD, &xprt->xpt_flags)) {
                 /* Don't enqueue dead transports */
                 dprintk("svc: transport %p is dead, not enqueued\n", xprt);
@@ -353,7 +350,14 @@ void svc_xprt_enqueue(struct svc_xprt *xprt)
         }
 
  process:
-        if (!list_empty(&pool->sp_threads)) {
+        /* Work out whether threads are available */
+        thread_avail = !list_empty(&pool->sp_threads);  /* threads are asleep */
+        if (pool->sp_nwaking >= SVC_MAX_WAKING) {
+                /* too many threads are runnable and trying to wake up */
+                thread_avail = 0;
+        }
+
+        if (thread_avail) {
                 rqstp = list_entry(pool->sp_threads.next,
                                    struct svc_rqst,
                                    rq_list);
@@ -368,6 +372,8 @@ void svc_xprt_enqueue(struct svc_xprt *xprt)
                 svc_xprt_get(xprt);
                 rqstp->rq_reserved = serv->sv_max_mesg;
                 atomic_add(rqstp->rq_reserved, &xprt->xpt_reserved);
+                rqstp->rq_waking = 1;
+                pool->sp_nwaking++;
                 BUG_ON(xprt->xpt_pool != pool);
                 wake_up(&rqstp->rq_wait);
         } else {
@@ -633,6 +639,11 @@ int svc_recv(struct svc_rqst *rqstp, long timeout)
                 return -EINTR;
 
         spin_lock_bh(&pool->sp_lock);
+        if (rqstp->rq_waking) {
+                rqstp->rq_waking = 0;
+                pool->sp_nwaking--;
+                BUG_ON(pool->sp_nwaking < 0);
+        }
         xprt = svc_xprt_dequeue(pool);
         if (xprt) {
                 rqstp->rq_xprt = xprt;