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Groups > linux.kernel > #1720386
| From | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [patch 14/41] x86/smp: Use static key for reschedule interrupt tracing |
| Date | 2017-08-25 22:10 +0200 |
| Message-ID | <uit5v-7Z-9@gated-at.bofh.it> (permalink) |
| References | <uikvf-2YQ-3@gated-at.bofh.it> <uikEW-3hj-11@gated-at.bofh.it> <uisM9-8cd-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Fri, 25 Aug 2017, Steven Rostedt wrote:
> On Fri, 25 Aug 2017 12:31:17 +0200
> Thomas Gleixner <tglx@linutronix.de> wrote:
>
>
> > -__visible void __irq_entry smp_trace_reschedule_interrupt(struct pt_regs *regs)
> > -{
> > - /*
> > - * Need to call irq_enter() before calling the trace point.
> > - * __smp_reschedule_interrupt() calls irq_enter/exit() too (in
> > - * scheduler_ipi(). This is OK, since those functions are allowed
> > - * to nest.
> > - */
> > - ipi_entering_ack_irq();
> > - trace_reschedule_entry(RESCHEDULE_VECTOR);
> > + if (trace_irqvectors_enabled()) {
> > + /*
> > + * scheduler_ipi() might call irq_enter() as well, but
> > + * nested calls are fine.
> > + */
> > + irq_enter();
> > + trace_reschedule_entry(RESCHEDULE_VECTOR);
> > + }
> > +
> > inc_irq_stat(irq_resched_count);
> > scheduler_ipi();
> > - trace_reschedule_exit(RESCHEDULE_VECTOR);
> > - exiting_irq();
> > +
> > + if (trace_irqvectors_enabled()) {
> > + trace_reschedule_exit(RESCHEDULE_VECTOR);
> > + irq_exit();
>
> This is racy. If the static key gets changed on one and not the other,
> we lose the irq_enter/irq_exit match.
Indeed. Good point. Fixed up version below.
Thanks,
tglx
8<---------------------
--- a/arch/x86/include/asm/hw_irq.h
+++ b/arch/x86/include/asm/hw_irq.h
@@ -48,7 +48,7 @@ extern asmlinkage void call_function_sin
#ifdef CONFIG_TRACING
/* Interrupt handlers registered during init_IRQ */
-extern void trace_reschedule_interrupt(void);
+#define trace_reschedule_interrupt reschedule_interrupt
#define trace_call_function_interrupt call_function_interrupt
#define trace_call_function_single_interrupt call_function_single_interrupt
#define trace_thermal_interrupt thermal_interrupt
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -254,37 +254,27 @@ static void native_stop_other_cpus(int w
}
/*
- * Reschedule call back.
+ * Reschedule call back. KVM uses this interrupt to force a cpu out of
+ * guest mode
*/
-static inline void __smp_reschedule_interrupt(void)
-{
- inc_irq_stat(irq_resched_count);
- scheduler_ipi();
-}
-
__visible void __irq_entry smp_reschedule_interrupt(struct pt_regs *regs)
{
ack_APIC_irq();
- __smp_reschedule_interrupt();
- /*
- * KVM uses this interrupt to force a cpu out of guest mode
- */
-}
-
-__visible void __irq_entry smp_trace_reschedule_interrupt(struct pt_regs *regs)
-{
- /*
- * Need to call irq_enter() before calling the trace point.
- * __smp_reschedule_interrupt() calls irq_enter/exit() too (in
- * scheduler_ipi(). This is OK, since those functions are allowed
- * to nest.
- */
- ipi_entering_ack_irq();
- trace_reschedule_entry(RESCHEDULE_VECTOR);
inc_irq_stat(irq_resched_count);
+
+ if (trace_irqvectors_enabled()) {
+ /*
+ * scheduler_ipi() might call irq_enter() as well, but
+ * nested calls are fine.
+ */
+ irq_enter();
+ trace_reschedule_entry(RESCHEDULE_VECTOR);
+ scheduler_ipi();
+ trace_reschedule_exit(RESCHEDULE_VECTOR);
+ irq_exit();
+ return;
+ }
scheduler_ipi();
- trace_reschedule_exit(RESCHEDULE_VECTOR);
- exiting_irq();
}
__visible void __irq_entry smp_call_function_interrupt(struct pt_regs *regs)
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[patch 00/41] x86: Cleanup IDT code Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
[patch 01/41] x86/irq: Remove vector_used_by_percpu_irq() Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
[patch 26/41] x86/idt: Consolidate IDT invalidation Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
[patch 06/41] x86/traps: Simplify pagefault tracing logic Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
Re: [patch 06/41] x86/traps: Simplify pagefault tracing logic Andy Lutomirski <luto@kernel.org> - 2017-08-25 17:00 +0200
Re: [patch 06/41] x86/traps: Simplify pagefault tracing logic Steven Rostedt <rostedt@goodmis.org> - 2017-08-25 17:20 +0200
Re: [patch 06/41] x86/traps: Simplify pagefault tracing logic Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 17:20 +0200
[patch 07/41] x86/apic: Remove the duplicated tracing version of local_timer_interrupt Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
Re: [patch 07/41] x86/apic: Remove the duplicated tracing version of local_timer_interrupt Steven Rostedt <rostedt@goodmis.org> - 2017-08-25 17:30 +0200
[patch 14/41] x86/smp: Use static key for reschedule interrupt tracing Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
Re: [patch 14/41] x86/smp: Use static key for reschedule interrupt tracing Steven Rostedt <rostedt@goodmis.org> - 2017-08-25 21:50 +0200
Re: [patch 14/41] x86/smp: Use static key for reschedule interrupt tracing Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 22:10 +0200
Re: [patch 14/41] x86/smp: Use static key for reschedule interrupt tracing Steven Rostedt <rostedt@goodmis.org> - 2017-08-25 23:20 +0200
[patch 05/41] x86/tracing: Introduce a static key for exception tracing Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
Re: [patch 05/41] x86/tracing: Introduce a static key for exception tracing Steven Rostedt <rostedt@goodmis.org> - 2017-08-25 17:30 +0200
[patch 10/41] x86/apic: Remove the duplicated tracing versions of interrupts Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
Re: [patch 10/41] x86/apic: Remove the duplicated tracing versions of interrupts Steven Rostedt <rostedt@goodmis.org> - 2017-08-25 17:50 +0200
Re: [patch 10/41] x86/apic: Remove the duplicated tracing versions of interrupts Peter Zijlstra <peterz@infradead.org> - 2017-08-28 10:00 +0200
[patch 11/41] x86/irqwork: Get rid of duplicated tracing interrupt code Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
Re: [patch 11/41] x86/irqwork: Get rid of duplicated tracing interrupt code Steven Rostedt <rostedt@goodmis.org> - 2017-08-25 18:00 +0200
[patch 23/41] x86/idt: Create file for IDT related code Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
[patch 03/41] x86/irq: Move ifdeffery to header file Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
Re: [patch 03/41] x86/irq: Move ifdeffery to header file Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 14:50 +0200
[patch 24/41] x86/idt: Move 32bit idt_descr to C code Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
[patch 16/41] x86/tracing: Disentangle pagefault and resched IPI tracing key Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
[patch 09/41] x86/irq: Get rid of duplicated trace_x86_platform_ipi() code Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
Re: [patch 09/41] x86/irq: Get rid of duplicated trace_x86_platform_ipi() code Steven Rostedt <rostedt@goodmis.org> - 2017-08-25 17:50 +0200
[patch 12/41] x86/mce: Remove duplicated tracing interrupt code Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
Re: [patch 12/41] x86/mce: Remove duplicated tracing interrupt code Steven Rostedt <rostedt@goodmis.org> - 2017-08-25 18:10 +0200
Re: [patch 12/41] x86/mce: Remove duplicated tracing interrupt code Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 18:20 +0200
[patch 21/41] x86/gdt: Use bitfields for initialization Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
[patch 28/41] x86/idt: Move early IDT setup out of 32bit asm Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
[patch 22/41] x86/ldttss: Cleanup 32bit descriptors Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
[patch 20/41] x86: Replace access to desc_struct:a/b fields Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
Re: [patch 20/41] x86: Replace access to desc_struct:a/b fields Juergen Gross <jgross@suse.com> - 2017-08-25 13:20 +0200
Re: [patch 20/41] x86: Replace access to desc_struct:a/b fields Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-08-25 16:00 +0200
Re: [patch 20/41] x86: Replace access to desc_struct:a/b fields Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 16:10 +0200
Re: [patch 20/41] x86: Replace access to desc_struct:a/b fields Steven Rostedt <rostedt@goodmis.org> - 2017-08-25 16:20 +0200
[patch 04/41] x86/boot: Move EISA setup to a proper place Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
Re: [patch 04/41] x86/boot: Move EISA setup to a proper place Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 14:00 +0200
[patch 25/41] x86/idt: Remove unused set_trap_gate() Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
[patch 08/41] x86/apic: Use this_cpu_ptr in local_timer_interrupt Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
[patch 15/41] x86/idt: Remove tracing idt completely Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 13:10 +0200
Re: [patch 15/41] x86/idt: Remove tracing idt completely Steven Rostedt <rostedt@goodmis.org> - 2017-08-25 23:20 +0200
Re: [patch 15/41] x86/idt: Remove tracing idt completely Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 23:30 +0200
Re: [patch 15/41] x86/idt: Remove tracing idt completely Thomas Gleixner <tglx@linutronix.de> - 2017-08-25 23:30 +0200
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