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Groups > linux.kernel > #1620673
| From | Steven Rostedt <rostedt@goodmis.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [for-next][PATCH 7/7] tracing: Make sure rcu_irq_enter() can work for trace_*_rcuidle() trace events |
| Date | 2017-04-10 22:00 +0200 |
| Message-ID | <tuNDI-5ev-13@gated-at.bofh.it> (permalink) |
| References | <tuNDI-5ev-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.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 f72fcfe0e66a..cc48cb2ce209 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);\
--
2.10.2
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[for-next][PATCH 0/7] tracing: Stack tracing and rcu modification updates Steven Rostedt <rostedt@goodmis.org> - 2017-04-10 22:00 +0200
[for-next][PATCH 6/7] rcu/tracing: Add rcu_disabled to denote when rcu_irq_enter() will not work Steven Rostedt <rostedt@goodmis.org> - 2017-04-10 22:00 +0200
[for-next][PATCH 4/7] tracing: Rename trace_active to disable_stack_tracer and inline its modification Steven Rostedt <rostedt@goodmis.org> - 2017-04-10 22:00 +0200
Re: [for-next][PATCH 4/7] tracing: Rename trace_active to disable_stack_tracer and inline its modification Valentin Rothberg <valentinrothberg@gmail.com> - 2017-04-13 10:00 +0200
Re: [for-next][PATCH 4/7] tracing: Rename trace_active to disable_stack_tracer and inline its modification Steven Rostedt <rostedt@goodmis.org> - 2017-04-13 16:10 +0200
[for-next][PATCH 7/7] tracing: Make sure rcu_irq_enter() can work for trace_*_rcuidle() trace events Steven Rostedt <rostedt@goodmis.org> - 2017-04-10 22:00 +0200
[for-next][PATCH 5/7] rcu: Fix dyntick-idle tracing Steven Rostedt <rostedt@goodmis.org> - 2017-04-10 22:00 +0200
[for-next][PATCH 1/7] ftrace: Add use of synchronize_rcu_tasks() with dynamic trampolines Steven Rostedt <rostedt@goodmis.org> - 2017-04-10 22:00 +0200
[for-next][PATCH 3/7] tracing: Add stack_tracer_disable/enable() functions Steven Rostedt <rostedt@goodmis.org> - 2017-04-10 22:00 +0200
[for-next][PATCH 2/7] tracing: Replace the per_cpu() with __this_cpu*() in trace_stack.c Steven Rostedt <rostedt@goodmis.org> - 2017-04-10 22:00 +0200
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