[PATCH tip/core/rcu 3/3] rcu, ftrace: fix RCU lockdep splat in ftrace_perf_buf_prepare()

Paul E. McKenney
2010-03-04T01:50:37Z

Change the pair of rcu_dereference() calls in ftrace_perf_buf_prepare()
to rcu_dereference_sched().

Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
include/trace/ftrace.h | 4 ++--
kernel/trace/trace_event_profile.c | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 0804cd5..601ad77 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -699,9 +699,9 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
* __cpu = smp_processor_id();
*
* if (in_nmi())
- * trace_buf = rcu_dereference(perf_trace_buf_nmi);
+ * trace_buf = rcu_dereference_sched(perf_trace_buf_nmi);
* else
- * trace_buf = rcu_dereference(perf_trace_buf);
+ * trace_buf = rcu_dereference_sched(perf_trace_buf);
*
* if (!trace_buf)
* goto end;
diff --git a/kernel/trace/trace_event_profile.c b/kernel/trace/trace_event_profile.c
index f0d6930..c1cc3ab 100644
--- a/kernel/trace/trace_event_profile.c
+++ b/kernel/trace/trace_event_profile.c
@@ -138,9 +138,9 @@ __kprobes void *ftrace_perf_buf_prepare(int size, unsigned short type,
cpu = smp_processor_id();

if (in_nmi())
- trace_buf = rcu_dereference(perf_trace_buf_nmi);
+ trace_buf = rcu_dereference_sched(perf_trace_buf_nmi);
else
- trace_buf = rcu_dereference(perf_trace_buf);
+ trace_buf = rcu_dereference_sched(perf_trace_buf);

if (!trace_buf)
goto err;
--
1.6.6