[RFC PATCH v2 3/8] sched, smp: Trace IPIs sent via send_call_function_single_ipi()

[Valentin Schneider]

send_call_function_single_ipi() is the thing that sends IPIs at the bottom
of smp_call_function*() via either generic_exec_single() or
smp_call_function_many_cond(). Give it an IPI-related tracepoint.

Note that this ends up tracing any IPI sent via __smp_call_single_queue(),
which covers __ttwu_queue_wakelist() and irq_work_queue_on() "for free".

Signed-off-by: Valentin Schneider <vschneid at redhat.com>
---
 arch/arm/kernel/smp.c   | 3 ---
 arch/arm64/kernel/smp.c | 1 -
 kernel/sched/core.c     | 7 +++++--
 kernel/smp.c            | 4 ++++
 4 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 978db2d96b446..3b280d55c1c40 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -48,9 +48,6 @@
 #include <asm/mach/arch.h>
 #include <asm/mpu.h>
 
-#define CREATE_TRACE_POINTS
-#include <trace/events/ipi.h>
-
 /*
  * as from 2.5, kernels no longer have an init_tasks structure
  * so we need some other way of telling a new secondary core
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index ffc5d76cf6955..937d2623e06ba 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -51,7 +51,6 @@
 #include <asm/ptrace.h>
 #include <asm/virt.h>
 
-#define CREATE_TRACE_POINTS
 #include <trace/events/ipi.h>
 
 DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index cb2aa2b54c7a4..02181f8072b5f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -81,6 +81,7 @@
 #include <linux/sched/rseq_api.h>
 #include <trace/events/sched.h>
 #undef CREATE_TRACE_POINTS
+#include <trace/events/ipi.h>
 
 #include "sched.h"
 #include "stats.h"
@@ -3746,10 +3747,12 @@ void send_call_function_single_ipi(int cpu)
 {
 	struct rq *rq = cpu_rq(cpu);
 
-	if (!set_nr_if_polling(rq->idle))
+	if (!set_nr_if_polling(rq->idle)) {
+		trace_ipi_send_cpumask(cpumask_of(cpu), _RET_IP_, NULL);
 		arch_send_call_function_single_ipi(cpu);
-	else
+	} else {
 		trace_sched_wake_idle_without_ipi(cpu);
+	}
 }
 
 /*
diff --git a/kernel/smp.c b/kernel/smp.c
index 06a413987a14a..e2ca1e2f31274 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -26,6 +26,10 @@
 #include <linux/sched/debug.h>
 #include <linux/jump_label.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/ipi.h>
+#undef CREATE_TRACE_POINTS
+
 #include "smpboot.h"
 #include "sched/smp.h"
 
-- 
2.31.1