Merge tag 'trace-fixes-v3.15-rc4-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "This contains two fixes.

  The first is a long standing bug that causes bogus data to show up in
  the refcnt field of the module_refcnt tracepoint.  It was introduced
  by a merge conflict resolution back in 2.6.35-rc days.

  The result should be 'refcnt = incs - decs', but instead it did
  'refcnt = incs + decs'.

  The second fix is to a bug that was introduced in this merge window
  that allowed for a tracepoint funcs pointer to be used after it was
  freed.  Moving the location of where the probes are released solved
  the problem"

* tag 'trace-fixes-v3.15-rc4-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracepoint: Fix use of tracepoint funcs after rcu free
  trace: module: Maintain a valid user count

2 files changed, 3 insertions, 3 deletions

diff --git a/include/trace/events/module.h b/include/trace/events/module.h
index ed0b2c599a64..7c5cbfe3fc49 100644
--- a/include/trace/events/module.h
+++ b/include/trace/events/module.h
@@ -80,7 +80,7 @@ DECLARE_EVENT_CLASS(module_refcnt,
 
         TP_fast_assign(
                 __entry->ip     = ip;
-                __entry->refcnt = __this_cpu_read(mod->refptr->incs) + __this_cpu_read(mod->refptr->decs);
+                __entry->refcnt = __this_cpu_read(mod->refptr->incs) - __this_cpu_read(mod->refptr->decs);
                 __assign_str(name, mod->name);
         ),
 
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index ac5b23cf7212..6620e5837ce2 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -188,7 +188,6 @@ static int tracepoint_add_func(struct tracepoint *tp,
                 WARN_ON_ONCE(1);
                 return PTR_ERR(old);
         }
-        release_probes(old);
 
         /*
          * rcu_assign_pointer has a smp_wmb() which makes sure that the new
@@ -200,6 +199,7 @@ static int tracepoint_add_func(struct tracepoint *tp,
         rcu_assign_pointer(tp->funcs, tp_funcs);
         if (!static_key_enabled(&tp->key))
                 static_key_slow_inc(&tp->key);
+        release_probes(old);
         return 0;
 }
 
@@ -221,7 +221,6 @@ static int tracepoint_remove_func(struct tracepoint *tp,
                 WARN_ON_ONCE(1);
                 return PTR_ERR(old);
         }
-        release_probes(old);
 
         if (!tp_funcs) {
                 /* Removed last function */
@@ -232,6 +231,7 @@ static int tracepoint_remove_func(struct tracepoint *tp,
                         static_key_slow_dec(&tp->key);
         }
         rcu_assign_pointer(tp->funcs, tp_funcs);
+        release_probes(old);
         return 0;
 }