[PATCH v3 2/2] powerpc: tracing: don't trace hcalls on offline CPUs

[Denis Kirjanov]

./drmgr -c cpu -a -r gives the following warning:

[ 2327.035563]
RCU used illegally from offline CPU!
rcu_scheduler_active = 1, debug_locks = 1
[ 2327.035564] no locks held by swapper/12/0.
[ 2327.035565]
stack backtrace:
[ 2327.035567] CPU: 12 PID: 0 Comm: swapper/12 Tainted: G S
4.3.0-rc3-00060-g353169a #5
[ 2327.035568] Call Trace:
[ 2327.035573] [c0000001d62578e0] [c0000000008977fc] .dump_stack+0x98/0xd4 (unreliable)
[ 2327.035577] [c0000001d6257960] [c000000000109bd8] .lockdep_rcu_suspicious+0x108/0x170
[ 2327.035580] [c0000001d62579f0] [c00000000006a1d0] .__trace_hcall_exit+0x2b0/0x2c0
[ 2327.035584] [c0000001d6257ab0] [c00000000006a2e8] plpar_hcall_norets_trace+0x70/0x8c
[ 2327.035588] [c0000001d6257b20] [c000000000067a14] .icp_hv_set_cpu_priority+0x54/0xc0
[ 2327.035592] [c0000001d6257ba0] [c000000000066c5c] .xics_teardown_cpu+0x5c/0xa0
[ 2327.035595] [c0000001d6257c20] [c0000000000747ac] .pseries_mach_cpu_die+0x6c/0x320
[ 2327.035598] [c0000001d6257cd0] [c0000000000439cc] .cpu_die+0x3c/0x60
[ 2327.035602] [c0000001d6257d40] [c0000000000183d8] .arch_cpu_idle_dead+0x28/0x40
[ 2327.035606] [c0000001d6257db0] [c0000000000ff1dc] .cpu_startup_entry+0x4fc/0x560
[ 2327.035610] [c0000001d6257ed0] [c000000000043728] .start_secondary+0x328/0x360
[ 2327.035614] [c0000001d6257f90] [c000000000008a6c] start_secondary_prolog+0x10/0x14
[ 2327.035620] cpu 12 (hwid 12) Ready to die...
[ 2327.144463] cpu 13 (hwid 13) Ready to die...
[ 2327.294180] cpu 14 (hwid 14) Ready to die...
[ 2327.403599] cpu 15 (hwid 15) Ready to die...

Make the hypervisor tracepoints conditional
by using TRACE_EVENT_FN_COND

Signed-off-by: Denis Kirjanov <kda at linux-powerpc.org>

v2 changes:
 - Use raw_smp_processor_id as suggested by BenH
 since since hcalls can be called from preemptable sections

v3 changes:
 - Fix the subject line
---
 arch/powerpc/include/asm/trace.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/trace.h b/arch/powerpc/include/asm/trace.h
index 8e86b48..32e36b1 100644
--- 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)
-- 
2.4.0