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| author |   Steven Rostedt (VMware) <rostedt@goodmis.org> | 2017-04-07 12:40:49 -0400 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2017-04-10 15:22:17 -0400 |
| commit | d54b6eeb553c89ed8d4c5a2ed73df374a45b9562 (patch) | |
| tree | 26ee9aadd39cb4f25fbd7f41e1adab23a51ccd35 /include/linux/tracepoint.h | |
| parent | rcu/tracing: Add rcu_disabled to denote when rcu_irq_enter() will not work (diff) | |
| download | linux-dev-d54b6eeb553c89ed8d4c5a2ed73df374a45b9562.tar.xz linux-dev-d54b6eeb553c89ed8d4c5a2ed73df374a45b9562.zip | |
tracing: Make sure rcu_irq_enter() can work for trace_*_rcuidle() trace events
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>
Diffstat (limited to 'include/linux/tracepoint.h')
| -rw-r--r-- | include/linux/tracepoint.h | 19 |
1 files 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);\ |