rcu, ftrace: Fix RCU lockdep splat in ftrace_perf_buf_prepare()
Paul E. McKenney [Thu, 4 Mar 2010 01:50:18 +0000 (17:50 -0800)]
Change the pair of rcu_dereference() calls in
ftrace_perf_buf_prepare() to rcu_dereference_sched().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1267667418-32233-3-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/trace/ftrace.h
kernel/trace/trace_event_profile.c

index 0804cd5..601ad77 100644 (file)
@@ -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;
index f0d6930..c1cc3ab 100644 (file)
@@ -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;