Commit 8d53dd54 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Ingo Molnar
Browse files

rcu, ftrace: Fix RCU lockdep splat in ftrace_perf_buf_prepare() 



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

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: default avatarFrederic 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: default avatarIngo Molnar <mingo@elte.hu>
parent 99ee4ca7

include/trace/ftrace.h

+2 −2
Original line number Diff line number Diff line
@@ -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;

kernel/trace/trace_event_profile.c

+2 −2
Original line number Diff line number Diff line
@@ -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;

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