trace: Allow idle-safe tracepoints to be called from irq

__DECLARE_TRACE_RCU() currently creates an _rcuidle() tracepoint which
may safely be invoked from what RCU considers to be an idle CPU.
However, these _rcuidle() tracepoints may -not- be invoked from the
handler of an irq taken from idle, because rcu_idle_enter() zeroes
RCU's nesting-level counter, so that the rcu_irq_exit() returning to
idle will trigger a WARN_ON_ONCE().

This commit therefore substitutes rcu_irq_enter() for rcu_idle_exit()
and rcu_irq_exit() for rcu_idle_enter() in order to make the _rcuidle()
tracepoints usable from irq handlers as well as from process context.

Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 2f322c3..f8e084d 100644 (file)
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -145,8 +145,8 @@ static inline void tracepoint_synchronize_unregister(void)
                                TP_PROTO(data_proto),                   \
                                TP_ARGS(data_args),                     \
                                TP_CONDITION(cond),                     \
-                               rcu_idle_exit(),                        \
-                               rcu_idle_enter());                      \
+                               rcu_irq_enter(),                        \
+                               rcu_irq_exit());                        \
        }
 #else
 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)