On Wed, Aug 17, 2016 at 12:33:06PM +0200, Peter Zijlstra wrote:
> So how to extend the same to function tracer .... we'd have to mark
> exiting_irq() -> irq_exit() and everything from that as notrace, which
> seems somewhat excessive, fragile and undesired because tracing those
> functions is useful in other context :/
Steve, would something like so work? It would completely kill function
tracing for the irq_work exit path, but that seems fairly sane over-all.
After all, all the common irq_work code is already notrace as well.
arch/x86/kernel/irq_work.c | 23 ++++++++++++++++++++---
1 file changed, 20 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/irq_work.c b/arch/x86/kernel/irq_work.c
index 3512ba607361..24de793c35c6 100644
--- a/arch/x86/kernel/irq_work.c
+++ b/arch/x86/kernel/irq_work.c
@@ -10,17 +10,34 @@
#include <asm/apic.h>
#include <asm/trace/irq_vectors.h>
-static inline void __smp_irq_work_interrupt(void)
+static inline notrace void __smp_irq_work_interrupt(void)
{
inc_irq_stat(apic_irq_work_irqs);
irq_work_run();
}
+static inline notrace void exiting_irq_work(void)
+{
+#ifdef CONFIG_TRACING
+ if (unlikely(1 /* function_tracing_enabled() */)) {
+ unsigned long trace_recursion = current->trace_recursion;
+
+ current->trace_recursion |= 1 << 10; /* TRACE_INTERNAL_IRQ_BIT
*/
+ barrier();
+ exiting_irq();
+ barrier();
+ current->trace_recursion = trace_recursion;
+ return;
+ }
+#endif
+ exiting_irq();
+}
+
__visible void smp_irq_work_interrupt(struct pt_regs *regs)
{
ipi_entering_ack_irq();
__smp_irq_work_interrupt();
- exiting_irq();
+ exiting_irq_work();
}
__visible void smp_trace_irq_work_interrupt(struct pt_regs *regs)
@@ -29,7 +46,7 @@ __visible void smp_trace_irq_work_interrupt(struct pt_regs
*regs)
trace_irq_work_entry(IRQ_WORK_VECTOR);
__smp_irq_work_interrupt();
trace_irq_work_exit(IRQ_WORK_VECTOR);
- exiting_irq();
+ exiting_irq_work();
}
void arch_irq_work_raise(void)
