From: Steven Rostedt <rostedt@goodmis.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH 7/5 v4] tracing: Make sure rcu_irq_enter() can work for trace_*_rcuidle() trace events
Date: Fri, 7 Apr 2017 15:41:17 -0400 [thread overview]
Message-ID: <20170407154117.253c84ae@gandalf.local.home> (raw)
In-Reply-To: <158560784.4550.1491589063819.JavaMail.zimbra@efficios.com>
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Stack tracing discovered that there's a small location inside the RCU
infrastructure where calling rcu_irq_enter() does not work. As trace events
use rcu_irq_enter() it must make sure that it is functionable. A check
against rcu_irq_enter_disabled() is added with a WARN_ON_ONCE() as no trace
event should ever be used in that part of RCU. If the warning is triggered,
then the trace event is ignored.
Restructure the __DO_TRACE() a bit to get rid of the prercu and postrcu,
and just have an rcucheck that does the work from within the _DO_TRACE()
macro. gcc optimization will compile out the rcucheck=0 case.
Link: http://lkml.kernel.org/r/20170405093207.404f8deb@gandalf.local.home
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
include/linux/tracepoint.h | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index f72fcfe..4ecb116 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -128,7 +128,7 @@ extern void syscall_unregfunc(void);
* as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
* "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
*/
-#define __DO_TRACE(tp, proto, args, cond, prercu, postrcu) \
+#define __DO_TRACE(tp, proto, args, cond, rcucheck) \
do { \
struct tracepoint_func *it_func_ptr; \
void *it_func; \
@@ -136,7 +136,11 @@ extern void syscall_unregfunc(void);
\
if (!(cond)) \
return; \
- prercu; \
+ if (rcucheck) { \
+ if (WARN_ON_ONCE(rcu_irq_enter_disabled())) \
+ return; \
+ rcu_irq_enter_irqson(); \
+ } \
rcu_read_lock_sched_notrace(); \
it_func_ptr = rcu_dereference_sched((tp)->funcs); \
if (it_func_ptr) { \
@@ -147,20 +151,19 @@ extern void syscall_unregfunc(void);
} while ((++it_func_ptr)->func); \
} \
rcu_read_unlock_sched_notrace(); \
- postrcu; \
+ if (rcucheck) \
+ rcu_irq_exit_irqson(); \
} while (0)
#ifndef MODULE
-#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
+#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
static inline void trace_##name##_rcuidle(proto) \
{ \
if (static_key_false(&__tracepoint_##name.key)) \
__DO_TRACE(&__tracepoint_##name, \
TP_PROTO(data_proto), \
TP_ARGS(data_args), \
- TP_CONDITION(cond), \
- rcu_irq_enter_irqson(), \
- rcu_irq_exit_irqson()); \
+ TP_CONDITION(cond),1); \
}
#else
#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
@@ -186,7 +189,7 @@ extern void syscall_unregfunc(void);
__DO_TRACE(&__tracepoint_##name, \
TP_PROTO(data_proto), \
TP_ARGS(data_args), \
- TP_CONDITION(cond),,); \
+ TP_CONDITION(cond),0); \
if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
rcu_read_lock_sched_notrace(); \
rcu_dereference_sched(__tracepoint_##name.funcs);\
--
2.9.3
next prev parent reply other threads:[~2017-04-07 19:41 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-07 14:01 [PATCH 0/5 v2] tracing: Add usecase of synchronize_rcu_tasks() and stack_tracer_disable() Steven Rostedt
2017-04-07 14:01 ` [PATCH 1/5 v2] ftrace: Add use of synchronize_rcu_tasks() with dynamic trampolines Steven Rostedt
2017-04-07 14:01 ` [PATCH 2/5 v2] tracing: Replace the per_cpu() with this_cpu() in trace_stack.c Steven Rostedt
2017-04-07 14:36 ` Paul E. McKenney
2017-04-07 14:48 ` Steven Rostedt
2017-04-07 15:08 ` Paul E. McKenney
2017-04-07 14:01 ` [PATCH 3/5 v2] tracing: Add stack_tracer_disable/enable() functions Steven Rostedt
2017-04-07 14:22 ` Steven Rostedt
2017-04-07 14:25 ` [PATCH 3/5 v2.1] " Steven Rostedt
2017-04-07 14:01 ` [PATCH 4/5 v2] tracing: Rename trace_active to disable_stack_tracer and inline its modification Steven Rostedt
2017-04-07 14:01 ` [PATCH 5/5 v2] rcu: Fix dyntick-idle tracing Steven Rostedt
2017-04-07 14:40 ` Paul E. McKenney
2017-04-07 14:53 ` Steven Rostedt
2017-04-07 15:09 ` Paul E. McKenney
2017-04-07 15:29 ` Steven Rostedt
2017-04-07 14:43 ` [PATCH 0/5 v2] tracing: Add usecase of synchronize_rcu_tasks() and stack_tracer_disable() Paul E. McKenney
2017-04-07 14:58 ` Steven Rostedt
2017-04-07 15:11 ` Paul E. McKenney
2017-04-07 15:28 ` Steven Rostedt
2017-04-07 16:35 ` [PATCH 6/5]rcu/tracing: Add rcu_disabled to denote when rcu_irq_enter() will not work Steven Rostedt
2017-04-07 16:42 ` Paul E. McKenney
2017-04-07 16:44 ` Steven Rostedt
2017-04-07 16:53 ` Paul E. McKenney
2017-04-07 17:03 ` [PATCH 6/5 v2] rcu/tracing: " Steven Rostedt
2017-04-07 17:15 ` Paul E. McKenney
2017-04-07 17:06 ` [PATCH 7/5] tracing: Make sure rcu_irq_enter() can work for trace_*_rcuidle() trace events Steven Rostedt
2017-04-07 17:15 ` Paul E. McKenney
2017-04-07 17:19 ` Mathieu Desnoyers
2017-04-07 17:26 ` Steven Rostedt
2017-04-07 17:32 ` Steven Rostedt
2017-04-07 17:49 ` Mathieu Desnoyers
2017-04-07 17:55 ` Steven Rostedt
2017-04-07 18:10 ` [PATCH 7/5 v3] " Steven Rostedt
2017-04-07 18:17 ` Mathieu Desnoyers
2017-04-07 19:41 ` Steven Rostedt [this message]
2017-04-07 19:43 ` [PATCH 7/5 v4] " Steven Rostedt
2017-04-10 17:11 ` Mathieu Desnoyers
2017-04-07 17:28 ` [PATCH 7/5] " Steven Rostedt
2017-04-07 17:48 ` [PATCH 7/5 v2] " Steven Rostedt
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