tracing: Forget about the NMI buffer for syscall events

We are never in an NMI context when we commit a syscall trace to
perf. So just forget about the nmi buffer there.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jason Baron <jbaron@redhat.com>
LKML-Reference: <1258863695-10464-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/trace/trace_syscalls.c

@@ -511,10 +511,7 @@ static void prof_syscall_enter(struct pt_regs *regs, long id)
 
 	cpu = smp_processor_id();
 
-	if (in_nmi())
-		trace_buf = rcu_dereference(perf_trace_buf_nmi);
-	else
-		trace_buf = rcu_dereference(perf_trace_buf);
+	trace_buf = rcu_dereference(perf_trace_buf);
 
 	if (!trace_buf)
 		goto end;
@@ -617,10 +614,7 @@ static void prof_syscall_exit(struct pt_regs *regs, long ret)
 
 	cpu = smp_processor_id();
 
-	if (in_nmi())
-		trace_buf = rcu_dereference(perf_trace_buf_nmi);
-	else
-		trace_buf = rcu_dereference(perf_trace_buf);
+	trace_buf = rcu_dereference(perf_trace_buf);
 
 	if (!trace_buf)
 		goto end;