1 files changed, 162 insertions, 130 deletions

diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index bbb3b044b877..c69358b3cf7f 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -220,9 +220,11 @@ static struct svc_xprt *__svc_xpo_create(struct svc_xprt_class *xcl,
  */
 static void svc_xprt_received(struct svc_xprt *xprt)
 {
-	WARN_ON_ONCE(!test_bit(XPT_BUSY, &xprt->xpt_flags));
-	if (!test_bit(XPT_BUSY, &xprt->xpt_flags))
+	if (!test_bit(XPT_BUSY, &xprt->xpt_flags)) {
+		WARN_ONCE(1, "xprt=0x%p already busy!", xprt);
 		return;
+	}
+
 	/* As soon as we clear busy, the xprt could be closed and
 	 * 'put', so we need a reference to call svc_xprt_do_enqueue with:
 	 */
@@ -310,25 +312,6 @@ char *svc_print_addr(struct svc_rqst *rqstp, char *buf, size_t len)
 }
 EXPORT_SYMBOL_GPL(svc_print_addr);
 
-/*
- * Queue up an idle server thread.  Must have pool->sp_lock held.
- * Note: this is really a stack rather than a queue, so that we only
- * use as many different threads as we need, and the rest don't pollute
- * the cache.
- */
-static void svc_thread_enqueue(struct svc_pool *pool, struct svc_rqst *rqstp)
-{
-	list_add(&rqstp->rq_list, &pool->sp_threads);
-}
-
-/*
- * Dequeue an nfsd thread.  Must have pool->sp_lock held.
- */
-static void svc_thread_dequeue(struct svc_pool *pool, struct svc_rqst *rqstp)
-{
-	list_del(&rqstp->rq_list);
-}
-
 static bool svc_xprt_has_something_to_do(struct svc_xprt *xprt)
 {
 	if (xprt->xpt_flags & ((1<<XPT_CONN)|(1<<XPT_CLOSE)))
@@ -341,11 +324,12 @@ static bool svc_xprt_has_something_to_do(struct svc_xprt *xprt)
 static void svc_xprt_do_enqueue(struct svc_xprt *xprt)
 {
 	struct svc_pool *pool;
-	struct svc_rqst	*rqstp;
+	struct svc_rqst	*rqstp = NULL;
 	int cpu;
+	bool queued = false;
 
 	if (!svc_xprt_has_something_to_do(xprt))
-		return;
+		goto out;
 
 	/* Mark transport as busy. It will remain in this state until
 	 * the provider calls svc_xprt_received. We update XPT_BUSY
@@ -355,43 +339,69 @@ static void svc_xprt_do_enqueue(struct svc_xprt *xprt)
 	if (test_and_set_bit(XPT_BUSY, &xprt->xpt_flags)) {
 		/* Don't enqueue transport while already enqueued */
 		dprintk("svc: transport %p busy, not enqueued\n", xprt);
-		return;
+		goto out;
 	}
 
 	cpu = get_cpu();
 	pool = svc_pool_for_cpu(xprt->xpt_server, cpu);
-	spin_lock_bh(&pool->sp_lock);
 
-	pool->sp_stats.packets++;
-
-	if (!list_empty(&pool->sp_threads)) {
-		rqstp = list_entry(pool->sp_threads.next,
-				   struct svc_rqst,
-				   rq_list);
-		dprintk("svc: transport %p served by daemon %p\n",
-			xprt, rqstp);
-		svc_thread_dequeue(pool, rqstp);
-		if (rqstp->rq_xprt)
-			printk(KERN_ERR
-				"svc_xprt_enqueue: server %p, rq_xprt=%p!\n",
-				rqstp, rqstp->rq_xprt);
-		/* Note the order of the following 3 lines:
-		 * We want to assign xprt to rqstp->rq_xprt only _after_
-		 * we've woken up the process, so that we don't race with
-		 * the lockless check in svc_get_next_xprt().
+	atomic_long_inc(&pool->sp_stats.packets);
+
+redo_search:
+	/* find a thread for this xprt */
+	rcu_read_lock();
+	list_for_each_entry_rcu(rqstp, &pool->sp_all_threads, rq_all) {
+		/* Do a lockless check first */
+		if (test_bit(RQ_BUSY, &rqstp->rq_flags))
+			continue;
+
+		/*
+		 * Once the xprt has been queued, it can only be dequeued by
+		 * the task that intends to service it. All we can do at that
+		 * point is to try to wake this thread back up so that it can
+		 * do so.
 		 */
-		svc_xprt_get(xprt);
+		if (!queued) {
+			spin_lock_bh(&rqstp->rq_lock);
+			if (test_and_set_bit(RQ_BUSY, &rqstp->rq_flags)) {
+				/* already busy, move on... */
+				spin_unlock_bh(&rqstp->rq_lock);
+				continue;
+			}
+
+			/* this one will do */
+			rqstp->rq_xprt = xprt;
+			svc_xprt_get(xprt);
+			spin_unlock_bh(&rqstp->rq_lock);
+		}
+		rcu_read_unlock();
+
+		atomic_long_inc(&pool->sp_stats.threads_woken);
 		wake_up_process(rqstp->rq_task);
-		rqstp->rq_xprt = xprt;
-		pool->sp_stats.threads_woken++;
-	} else {
+		put_cpu();
+		goto out;
+	}
+	rcu_read_unlock();
+
+	/*
+	 * We didn't find an idle thread to use, so we need to queue the xprt.
+	 * Do so and then search again. If we find one, we can't hook this one
+	 * up to it directly but we can wake the thread up in the hopes that it
+	 * will pick it up once it searches for a xprt to service.
+	 */
+	if (!queued) {
+		queued = true;
 		dprintk("svc: transport %p put into queue\n", xprt);
+		spin_lock_bh(&pool->sp_lock);
 		list_add_tail(&xprt->xpt_ready, &pool->sp_sockets);
 		pool->sp_stats.sockets_queued++;
+		spin_unlock_bh(&pool->sp_lock);
+		goto redo_search;
 	}
-
-	spin_unlock_bh(&pool->sp_lock);
+	rqstp = NULL;
 	put_cpu();
+out:
+	trace_svc_xprt_do_enqueue(xprt, rqstp);
 }
 
 /*
@@ -408,22 +418,28 @@ void svc_xprt_enqueue(struct svc_xprt *xprt)
 EXPORT_SYMBOL_GPL(svc_xprt_enqueue);
 
 /*
- * Dequeue the first transport.  Must be called with the pool->sp_lock held.
+ * Dequeue the first transport, if there is one.
  */
 static struct svc_xprt *svc_xprt_dequeue(struct svc_pool *pool)
 {
-	struct svc_xprt	*xprt;
+	struct svc_xprt	*xprt = NULL;
 
 	if (list_empty(&pool->sp_sockets))
-		return NULL;
-
-	xprt = list_entry(pool->sp_sockets.next,
-			  struct svc_xprt, xpt_ready);
-	list_del_init(&xprt->xpt_ready);
+		goto out;
 
-	dprintk("svc: transport %p dequeued, inuse=%d\n",
-		xprt, atomic_read(&xprt->xpt_ref.refcount));
+	spin_lock_bh(&pool->sp_lock);
+	if (likely(!list_empty(&pool->sp_sockets))) {
+		xprt = list_first_entry(&pool->sp_sockets,
+					struct svc_xprt, xpt_ready);
+		list_del_init(&xprt->xpt_ready);
+		svc_xprt_get(xprt);
 
+		dprintk("svc: transport %p dequeued, inuse=%d\n",
+			xprt, atomic_read(&xprt->xpt_ref.refcount));
+	}
+	spin_unlock_bh(&pool->sp_lock);
+out:
+	trace_svc_xprt_dequeue(xprt);
 	return xprt;
 }
 
@@ -484,34 +500,36 @@ static void svc_xprt_release(struct svc_rqst *rqstp)
 }
 
 /*
- * External function to wake up a server waiting for data
- * This really only makes sense for services like lockd
- * which have exactly one thread anyway.
+ * Some svc_serv's will have occasional work to do, even when a xprt is not
+ * waiting to be serviced. This function is there to "kick" a task in one of
+ * those services so that it can wake up and do that work. Note that we only
+ * bother with pool 0 as we don't need to wake up more than one thread for
+ * this purpose.
  */
 void svc_wake_up(struct svc_serv *serv)
 {
 	struct svc_rqst	*rqstp;
-	unsigned int i;
 	struct svc_pool *pool;
 
-	for (i = 0; i < serv->sv_nrpools; i++) {
-		pool = &serv->sv_pools[i];
+	pool = &serv->sv_pools[0];
 
-		spin_lock_bh(&pool->sp_lock);
-		if (!list_empty(&pool->sp_threads)) {
-			rqstp = list_entry(pool->sp_threads.next,
-					   struct svc_rqst,
-					   rq_list);
-			dprintk("svc: daemon %p woken up.\n", rqstp);
-			/*
-			svc_thread_dequeue(pool, rqstp);
-			rqstp->rq_xprt = NULL;
-			 */
-			wake_up_process(rqstp->rq_task);
-		} else
-			pool->sp_task_pending = 1;
-		spin_unlock_bh(&pool->sp_lock);
+	rcu_read_lock();
+	list_for_each_entry_rcu(rqstp, &pool->sp_all_threads, rq_all) {
+		/* skip any that aren't queued */
+		if (test_bit(RQ_BUSY, &rqstp->rq_flags))
+			continue;
+		rcu_read_unlock();
+		dprintk("svc: daemon %p woken up.\n", rqstp);
+		wake_up_process(rqstp->rq_task);
+		trace_svc_wake_up(rqstp->rq_task->pid);
+		return;
 	}
+	rcu_read_unlock();
+
+	/* No free entries available */
+	set_bit(SP_TASK_PENDING, &pool->sp_flags);
+	smp_wmb();
+	trace_svc_wake_up(0);
 }
 EXPORT_SYMBOL_GPL(svc_wake_up);
 
@@ -622,75 +640,86 @@ static int svc_alloc_arg(struct svc_rqst *rqstp)
 	return 0;
 }
 
+static bool
+rqst_should_sleep(struct svc_rqst *rqstp)
+{
+	struct svc_pool		*pool = rqstp->rq_pool;
+
+	/* did someone call svc_wake_up? */
+	if (test_and_clear_bit(SP_TASK_PENDING, &pool->sp_flags))
+		return false;
+
+	/* was a socket queued? */
+	if (!list_empty(&pool->sp_sockets))
+		return false;
+
+	/* are we shutting down? */
+	if (signalled() || kthread_should_stop())
+		return false;
+
+	/* are we freezing? */
+	if (freezing(current))
+		return false;
+
+	return true;
+}
+
 static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout)
 {
 	struct svc_xprt *xprt;
 	struct svc_pool		*pool = rqstp->rq_pool;
 	long			time_left = 0;
 
+	/* rq_xprt should be clear on entry */
+	WARN_ON_ONCE(rqstp->rq_xprt);
+
 	/* Normally we will wait up to 5 seconds for any required
 	 * cache information to be provided.
 	 */
 	rqstp->rq_chandle.thread_wait = 5*HZ;
 
-	spin_lock_bh(&pool->sp_lock);
 	xprt = svc_xprt_dequeue(pool);
 	if (xprt) {
 		rqstp->rq_xprt = xprt;
-		svc_xprt_get(xprt);
 
 		/* As there is a shortage of threads and this request
 		 * had to be queued, don't allow the thread to wait so
 		 * long for cache updates.
 		 */
 		rqstp->rq_chandle.thread_wait = 1*HZ;
-		pool->sp_task_pending = 0;
-	} else {
-		if (pool->sp_task_pending) {
-			pool->sp_task_pending = 0;
-			xprt = ERR_PTR(-EAGAIN);
-			goto out;
-		}
-		/*
-		 * We have to be able to interrupt this wait
-		 * to bring down the daemons ...
-		 */
-		set_current_state(TASK_INTERRUPTIBLE);
+		clear_bit(SP_TASK_PENDING, &pool->sp_flags);
+		return xprt;
+	}
 
-		/* No data pending. Go to sleep */
-		svc_thread_enqueue(pool, rqstp);
-		spin_unlock_bh(&pool->sp_lock);
+	/*
+	 * We have to be able to interrupt this wait
+	 * to bring down the daemons ...
+	 */
+	set_current_state(TASK_INTERRUPTIBLE);
+	clear_bit(RQ_BUSY, &rqstp->rq_flags);
+	smp_mb();
 
-		if (!(signalled() || kthread_should_stop())) {
-			time_left = schedule_timeout(timeout);
-			__set_current_state(TASK_RUNNING);
+	if (likely(rqst_should_sleep(rqstp)))
+		time_left = schedule_timeout(timeout);
+	else
+		__set_current_state(TASK_RUNNING);
 
-			try_to_freeze();
+	try_to_freeze();
 
-			xprt = rqstp->rq_xprt;
-			if (xprt != NULL)
-				return xprt;
-		} else
-			__set_current_state(TASK_RUNNING);
+	spin_lock_bh(&rqstp->rq_lock);
+	set_bit(RQ_BUSY, &rqstp->rq_flags);
+	spin_unlock_bh(&rqstp->rq_lock);
 
-		spin_lock_bh(&pool->sp_lock);
-		if (!time_left)
-			pool->sp_stats.threads_timedout++;
+	xprt = rqstp->rq_xprt;
+	if (xprt != NULL)
+		return xprt;
 
-		xprt = rqstp->rq_xprt;
-		if (!xprt) {
-			svc_thread_dequeue(pool, rqstp);
-			spin_unlock_bh(&pool->sp_lock);
-			dprintk("svc: server %p, no data yet\n", rqstp);
-			if (signalled() || kthread_should_stop())
-				return ERR_PTR(-EINTR);
-			else
-				return ERR_PTR(-EAGAIN);
-		}
-	}
-out:
-	spin_unlock_bh(&pool->sp_lock);
-	return xprt;
+	if (!time_left)
+		atomic_long_inc(&pool->sp_stats.threads_timedout);
+
+	if (signalled() || kthread_should_stop())
+		return ERR_PTR(-EINTR);
+	return ERR_PTR(-EAGAIN);
 }
 
 static void svc_add_new_temp_xprt(struct svc_serv *serv, struct svc_xprt *newxpt)
@@ -719,7 +748,7 @@ static int svc_handle_xprt(struct svc_rqst *rqstp, struct svc_xprt *xprt)
 		dprintk("svc_recv: found XPT_CLOSE\n");
 		svc_delete_xprt(xprt);
 		/* Leave XPT_BUSY set on the dead xprt: */
-		return 0;
+		goto out;
 	}
 	if (test_bit(XPT_LISTENER, &xprt->xpt_flags)) {
 		struct svc_xprt *newxpt;
@@ -750,6 +779,8 @@ static int svc_handle_xprt(struct svc_rqst *rqstp, struct svc_xprt *xprt)
 	}
 	/* clear XPT_BUSY: */
 	svc_xprt_received(xprt);
+out:
+	trace_svc_handle_xprt(xprt, len);
 	return len;
 }
 
@@ -797,7 +828,10 @@ int svc_recv(struct svc_rqst *rqstp, long timeout)
 
 	clear_bit(XPT_OLD, &xprt->xpt_flags);
 
-	rqstp->rq_secure = xprt->xpt_ops->xpo_secure_port(rqstp);
+	if (xprt->xpt_ops->xpo_secure_port(rqstp))
+		set_bit(RQ_SECURE, &rqstp->rq_flags);
+	else
+		clear_bit(RQ_SECURE, &rqstp->rq_flags);
 	rqstp->rq_chandle.defer = svc_defer;
 	rqstp->rq_xid = svc_getu32(&rqstp->rq_arg.head[0]);
 
@@ -895,7 +929,6 @@ static void svc_age_temp_xprts(unsigned long closure)
 			continue;
 		list_del_init(le);
 		set_bit(XPT_CLOSE, &xprt->xpt_flags);
-		set_bit(XPT_DETACHED, &xprt->xpt_flags);
 		dprintk("queuing xprt %p for closing\n", xprt);
 
 		/* a thread will dequeue and close it soon */
@@ -935,8 +968,7 @@ static void svc_delete_xprt(struct svc_xprt *xprt)
 	xprt->xpt_ops->xpo_detach(xprt);
 
 	spin_lock_bh(&serv->sv_lock);
-	if (!test_and_set_bit(XPT_DETACHED, &xprt->xpt_flags))
-		list_del_init(&xprt->xpt_list);
+	list_del_init(&xprt->xpt_list);
 	WARN_ON_ONCE(!list_empty(&xprt->xpt_ready));
 	if (test_bit(XPT_TEMP, &xprt->xpt_flags))
 		serv->sv_tmpcnt--;
@@ -1080,7 +1112,7 @@ static struct cache_deferred_req *svc_defer(struct cache_req *req)
 	struct svc_rqst *rqstp = container_of(req, struct svc_rqst, rq_chandle);
 	struct svc_deferred_req *dr;
 
-	if (rqstp->rq_arg.page_len || !rqstp->rq_usedeferral)
+	if (rqstp->rq_arg.page_len || !test_bit(RQ_USEDEFERRAL, &rqstp->rq_flags))
 		return NULL; /* if more than a page, give up FIXME */
 	if (rqstp->rq_deferred) {
 		dr = rqstp->rq_deferred;
@@ -1109,7 +1141,7 @@ static struct cache_deferred_req *svc_defer(struct cache_req *req)
 	}
 	svc_xprt_get(rqstp->rq_xprt);
 	dr->xprt = rqstp->rq_xprt;
-	rqstp->rq_dropme = true;
+	set_bit(RQ_DROPME, &rqstp->rq_flags);
 
 	dr->handle.revisit = svc_revisit;
 	return &dr->handle;
@@ -1311,10 +1343,10 @@ static int svc_pool_stats_show(struct seq_file *m, void *p)
 
 	seq_printf(m, "%u %lu %lu %lu %lu\n",
 		pool->sp_id,
-		pool->sp_stats.packets,
+		(unsigned long)atomic_long_read(&pool->sp_stats.packets),
 		pool->sp_stats.sockets_queued,
-		pool->sp_stats.threads_woken,
-		pool->sp_stats.threads_timedout);
+		(unsigned long)atomic_long_read(&pool->sp_stats.threads_woken),
+		(unsigned long)atomic_long_read(&pool->sp_stats.threads_timedout));
 
 	return 0;
 }