powerpc/pseries: Don't trace hcalls on offline CPUs

If a cpu is hotplugged while the hcall trace points are active, it's
possible to hit a warning from RCU due to the trace points calling into
RCU from an offline cpu, eg:

  RCU used illegally from offline CPU!
  rcu_scheduler_active = 1, debug_locks = 1

Make the hypervisor tracepoints conditional by using
TRACE_EVENT_FN_COND.

Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/include/asm/trace.h b/arch/powerpc/include/asm/trace.h
index 8e86b48..32e36b1 100644 (file)
--- a/arch/powerpc/include/asm/trace.h
+++ b/arch/powerpc/include/asm/trace.h
@@ -57,12 +57,14 @@ DEFINE_EVENT(ppc64_interrupt_class, timer_interrupt_exit,
 extern void hcall_tracepoint_regfunc(void);
 extern void hcall_tracepoint_unregfunc(void);
 
-TRACE_EVENT_FN(hcall_entry,
+TRACE_EVENT_FN_COND(hcall_entry,
 
        TP_PROTO(unsigned long opcode, unsigned long *args),
 
        TP_ARGS(opcode, args),
 
+       TP_CONDITION(cpu_online(raw_smp_processor_id())),
+
        TP_STRUCT__entry(
                __field(unsigned long, opcode)
        ),
@@ -76,13 +78,15 @@ TRACE_EVENT_FN(hcall_entry,
        hcall_tracepoint_regfunc, hcall_tracepoint_unregfunc
 );
 
-TRACE_EVENT_FN(hcall_exit,
+TRACE_EVENT_FN_COND(hcall_exit,
 
        TP_PROTO(unsigned long opcode, unsigned long retval,
                unsigned long *retbuf),
 
        TP_ARGS(opcode, retval, retbuf),
 
+       TP_CONDITION(cpu_online(raw_smp_processor_id())),
+
        TP_STRUCT__entry(
                __field(unsigned long, opcode)
                __field(unsigned long, retval)