| Message ID | 20230112195541.477416709@infradead.org (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | cpuidle,rcu: Clean up the mess | expand |
Hi Peter, On Thu, 12 Jan 2023 20:43:49 +0100 Peter Zijlstra <peterz@infradead.org> wrote: > Robot reported that trace_hardirqs_{on,off}() tickle the forbidden > _rcuidle() tracepoint through local_irq_{en,dis}able(). > > For 'sane' configs, these calls will only happen with RCU enabled and > as such can use the regular tracepoint. This also means it's possible > to trace them from NMI context again. > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> The code looks good to me. I just have a question about comment. > --- > kernel/trace/trace_preemptirq.c | 21 +++++++++++++-------- > 1 file changed, 13 insertions(+), 8 deletions(-) > > --- a/kernel/trace/trace_preemptirq.c > +++ b/kernel/trace/trace_preemptirq.c > @@ -20,6 +20,15 @@ > static DEFINE_PER_CPU(int, tracing_irq_cpu); > > /* > + * ... Is this intended? Wouldn't you leave any comment here? Thank you, > + */ > +#ifdef CONFIG_ARCH_WANTS_NO_INSTR > +#define trace(point) trace_##point > +#else > +#define trace(point) if (!in_nmi()) trace_##point##_rcuidle > +#endif > + > +/* > * Like trace_hardirqs_on() but without the lockdep invocation. This is > * used in the low level entry code where the ordering vs. RCU is important > * and lockdep uses a staged approach which splits the lockdep hardirq > @@ -28,8 +37,7 @@ static DEFINE_PER_CPU(int, tracing_irq_c > void trace_hardirqs_on_prepare(void) > { > if (this_cpu_read(tracing_irq_cpu)) { > - if (!in_nmi()) > - trace_irq_enable(CALLER_ADDR0, CALLER_ADDR1); > + trace(irq_enable)(CALLER_ADDR0, CALLER_ADDR1); > tracer_hardirqs_on(CALLER_ADDR0, CALLER_ADDR1); > this_cpu_write(tracing_irq_cpu, 0); > } > @@ -40,8 +48,7 @@ NOKPROBE_SYMBOL(trace_hardirqs_on_prepar > void trace_hardirqs_on(void) > { > if (this_cpu_read(tracing_irq_cpu)) { > - if (!in_nmi()) > - trace_irq_enable_rcuidle(CALLER_ADDR0, CALLER_ADDR1); > + trace(irq_enable)(CALLER_ADDR0, CALLER_ADDR1); > tracer_hardirqs_on(CALLER_ADDR0, CALLER_ADDR1); > this_cpu_write(tracing_irq_cpu, 0); > } > @@ -63,8 +70,7 @@ void trace_hardirqs_off_finish(void) > if (!this_cpu_read(tracing_irq_cpu)) { > this_cpu_write(tracing_irq_cpu, 1); > tracer_hardirqs_off(CALLER_ADDR0, CALLER_ADDR1); > - if (!in_nmi()) > - trace_irq_disable(CALLER_ADDR0, CALLER_ADDR1); > + trace(irq_disable)(CALLER_ADDR0, CALLER_ADDR1); > } > > } > @@ -78,8 +84,7 @@ void trace_hardirqs_off(void) > if (!this_cpu_read(tracing_irq_cpu)) { > this_cpu_write(tracing_irq_cpu, 1); > tracer_hardirqs_off(CALLER_ADDR0, CALLER_ADDR1); > - if (!in_nmi()) > - trace_irq_disable_rcuidle(CALLER_ADDR0, CALLER_ADDR1); > + trace(irq_disable)(CALLER_ADDR0, CALLER_ADDR1); > } > } > EXPORT_SYMBOL(trace_hardirqs_off); > >
On Tue, Jan 17, 2023 at 01:24:46PM +0900, Masami Hiramatsu wrote: > Hi Peter, > > On Thu, 12 Jan 2023 20:43:49 +0100 > Peter Zijlstra <peterz@infradead.org> wrote: > > > Robot reported that trace_hardirqs_{on,off}() tickle the forbidden > > _rcuidle() tracepoint through local_irq_{en,dis}able(). > > > > For 'sane' configs, these calls will only happen with RCU enabled and > > as such can use the regular tracepoint. This also means it's possible > > to trace them from NMI context again. > > > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > > The code looks good to me. I just have a question about comment. > > > --- > > kernel/trace/trace_preemptirq.c | 21 +++++++++++++-------- > > 1 file changed, 13 insertions(+), 8 deletions(-) > > > > --- a/kernel/trace/trace_preemptirq.c > > +++ b/kernel/trace/trace_preemptirq.c > > @@ -20,6 +20,15 @@ > > static DEFINE_PER_CPU(int, tracing_irq_cpu); > > > > /* > > + * ... > > Is this intended? Wouldn't you leave any comment here? I indeed forgot to write the comment before posting, my bad :/ Ingo fixed it up when he applied.
--- a/kernel/trace/trace_preemptirq.c +++ b/kernel/trace/trace_preemptirq.c @@ -20,6 +20,15 @@ static DEFINE_PER_CPU(int, tracing_irq_cpu); /* + * ... + */ +#ifdef CONFIG_ARCH_WANTS_NO_INSTR +#define trace(point) trace_##point +#else +#define trace(point) if (!in_nmi()) trace_##point##_rcuidle +#endif + +/* * Like trace_hardirqs_on() but without the lockdep invocation. This is * used in the low level entry code where the ordering vs. RCU is important * and lockdep uses a staged approach which splits the lockdep hardirq @@ -28,8 +37,7 @@ static DEFINE_PER_CPU(int, tracing_irq_c void trace_hardirqs_on_prepare(void) { if (this_cpu_read(tracing_irq_cpu)) { - if (!in_nmi()) - trace_irq_enable(CALLER_ADDR0, CALLER_ADDR1); + trace(irq_enable)(CALLER_ADDR0, CALLER_ADDR1); tracer_hardirqs_on(CALLER_ADDR0, CALLER_ADDR1); this_cpu_write(tracing_irq_cpu, 0); } @@ -40,8 +48,7 @@ NOKPROBE_SYMBOL(trace_hardirqs_on_prepar void trace_hardirqs_on(void) { if (this_cpu_read(tracing_irq_cpu)) { - if (!in_nmi()) - trace_irq_enable_rcuidle(CALLER_ADDR0, CALLER_ADDR1); + trace(irq_enable)(CALLER_ADDR0, CALLER_ADDR1); tracer_hardirqs_on(CALLER_ADDR0, CALLER_ADDR1); this_cpu_write(tracing_irq_cpu, 0); } @@ -63,8 +70,7 @@ void trace_hardirqs_off_finish(void) if (!this_cpu_read(tracing_irq_cpu)) { this_cpu_write(tracing_irq_cpu, 1); tracer_hardirqs_off(CALLER_ADDR0, CALLER_ADDR1); - if (!in_nmi()) - trace_irq_disable(CALLER_ADDR0, CALLER_ADDR1); + trace(irq_disable)(CALLER_ADDR0, CALLER_ADDR1); } } @@ -78,8 +84,7 @@ void trace_hardirqs_off(void) if (!this_cpu_read(tracing_irq_cpu)) { this_cpu_write(tracing_irq_cpu, 1); tracer_hardirqs_off(CALLER_ADDR0, CALLER_ADDR1); - if (!in_nmi()) - trace_irq_disable_rcuidle(CALLER_ADDR0, CALLER_ADDR1); + trace(irq_disable)(CALLER_ADDR0, CALLER_ADDR1); } } EXPORT_SYMBOL(trace_hardirqs_off);
Robot reported that trace_hardirqs_{on,off}() tickle the forbidden _rcuidle() tracepoint through local_irq_{en,dis}able(). For 'sane' configs, these calls will only happen with RCU enabled and as such can use the regular tracepoint. This also means it's possible to trace them from NMI context again. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- kernel/trace/trace_preemptirq.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-)