The IRQ disable/enable tracepoints are currently gated behind
TRACE_IRQFLAGS, a hidden config that cannot be selected directly by
users. It is only enabled when selected by PROVE_LOCKING or
IRQSOFF_TRACER, both of which carry overhead beyond what is needed
for just the tracepoints.
Introduce TRACE_IRQFLAGS_TOGGLE, a user-selectable config that enables
the irq_disable and irq_enable tracepoints independently. It is
mutually exclusive with TRACE_IRQFLAGS and mirrors how
TRACE_PREEMPT_TOGGLE works for preemption tracepoints.
Make this option depend on CONFIG_JUMP_LABEL to avoid a circular header
dependency. Without TRACE_IRQFLAGS, irqflags.h must check the static
key before invoking the tracepoint. Using tracepoint_enabled() for this
check pulls in tracepoint_defs.h, which eventually includes atomic.h
and cmpxchg.h, circling back to irqflags.h. Enforcing CONFIG_JUMP_LABEL
allows the use of static_key_false() directly, avoiding the inclusion
of the full tracepoint header chain and preventing the cycle.
Signed-off-by: Wander Lairson Costa <wander@redhat.com>
---
kernel/trace/Kconfig | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index e007459ecf361..8bea77b5f1200 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -162,7 +162,7 @@ config RING_BUFFER_ALLOW_SWAP
config PREEMPTIRQ_TRACEPOINTS
bool
- depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS
+ depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS || TRACE_IRQFLAGS_TOGGLE
select TRACING
default y
help
@@ -418,6 +418,17 @@ config TRACE_PREEMPT_TOGGLE
Enables hooks into preemption disable and enable paths for
tracing or latency measurement.
+config TRACE_IRQFLAGS_TOGGLE
+ bool "IRQ disable/enable tracing hooks"
+ default n
+ depends on TRACE_IRQFLAGS_SUPPORT && JUMP_LABEL && !TRACE_IRQFLAGS
+ help
+ Enables hooks into IRQ disable and enable paths for tracing.
+
+ This provides the irq_disable and irq_enable tracepoints
+ without pulling in the full TRACE_IRQFLAGS infrastructure
+ used by lockdep and the irqsoff latency tracer.
+
config IRQSOFF_TRACER
bool "Interrupts-off Latency Tracer"
default n
--
2.53.0