sunrpc: add some tracepoints around enqueue and dequeue of svc_xprt

These were useful when I was tracking down a race condition between
svc_xprt_do_enqueue and svc_get_next_xprt.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 15 insertions, 7 deletions

diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index ed90d955f733..73d40bd1839a 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -322,12 +322,12 @@ 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
@@ -337,7 +337,7 @@ 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();
@@ -377,7 +377,7 @@ redo_search:
                 atomic_long_inc(&pool->sp_stats.threads_woken);
                 wake_up_process(rqstp->rq_task);
                 put_cpu();
-                return;
+                goto out;
         }
         rcu_read_unlock();
 
@@ -396,7 +396,10 @@ redo_search:
                 spin_unlock_bh(&pool->sp_lock);
                 goto redo_search;
         }
+        rqstp = NULL;
         put_cpu();
+out:
+        trace_svc_xprt_do_enqueue(xprt, rqstp);
 }
 
 /*
@@ -420,7 +423,7 @@ static struct svc_xprt *svc_xprt_dequeue(struct svc_pool *pool)
         struct svc_xprt *xprt = NULL;
 
         if (list_empty(&pool->sp_sockets))
-                return NULL;
+                goto out;
 
         spin_lock_bh(&pool->sp_lock);
         if (likely(!list_empty(&pool->sp_sockets))) {
@@ -433,7 +436,8 @@ static struct svc_xprt *svc_xprt_dequeue(struct svc_pool *pool)
                         xprt, atomic_read(&xprt->xpt_ref.refcount));
         }
         spin_unlock_bh(&pool->sp_lock);
-
+out:
+        trace_svc_xprt_dequeue(xprt);
         return xprt;
 }
 
@@ -515,6 +519,7 @@ void svc_wake_up(struct svc_serv *serv)
                 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();
@@ -522,6 +527,7 @@ void svc_wake_up(struct svc_serv *serv)
         /* 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);
 
@@ -740,7 +746,7 @@ 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;
@@ -771,6 +777,8 @@ 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;
 }