From mboxrd@z Thu Jan 1 00:00:00 1970 From: Masami Hiramatsu (Google) Subject: Re: [PATCH v3 35/51] trace,hardirq: No moar _rcuidle() tracing Date: Tue, 17 Jan 2023 13:24:46 +0900 Message-ID: <20230117132446.02ec12e4c10718de27790900@kernel.org> References: <20230112194314.845371875@infradead.org> <20230112195541.477416709@infradead.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1673929510; bh=LKPfAbcdavLMCpifQk05Aqw+1tD2xg5qsuB6VorVVnI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=rvDfVQk7Tsas4+LZFK04iCV/SqfYXmqYXLFi42JOngYW1dOP0QSo6CLiBkpjYosKx nKUcD4fx6Lu1RT5hJ5yblHd47Jqpvv59kmEAKtriWUWkTZ7hmC4Za3q3BgpEtr891G Uhe5azCk4FahsTTDCEc3lE2+MzsUQWKU5CAcTO6IYBsGKCz8NivYw+lk7qeBhykDxt x23XNA0A5LxituWhIHyg6sCe7NTSUKsY2ON6C3g6I/nFT8i/VEH7jmIvKLWoo8AYZN JlOlRfIFLAGKs5+FVWy9q/WwqqbuzK/Mvbqfsgyxm4gYqDdXx2B1Vx+ckQBMj8vEfk ICBnmkeUNpdwg== In-Reply-To: <20230112195541.477416709@infradead.org> List-ID: Content-Type: text/plain; charset="us-ascii" To: Peter Zijlstra Cc: richard.henderson@linaro.org, ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@kernel.org, linux@armlinux.org.uk, nsekhar@ti.com, brgl@bgdev.pl, ulli.kroll@googlemail.com, linus.walleij@linaro.org, shawnguo@kernel.org, Sascha Hauer , kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, tony@atomide.com, khilman@kernel.org, krzysztof.kozlowski@linaro.org, alim.akhtar@samsung.com, catalin.marinas@arm.com, will@kernel.org, guoren@kernel.org, bcain@quicinc.com, chenhuacai@kernel.org, kernel@xen0n.name, geert@linux-m68k.org, sammy@sammy.net, monstr@monstr.eu, tsbogend@alpha.franken.de, dinguyen@kernel.org, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, James.Bottomley@HansenPartnership.com, deller@gmx.de, mpe@ellerman.id.au Hi Peter, On Thu, 12 Jan 2023 20:43:49 +0100 Peter Zijlstra 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) 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); > > -- Masami Hiramatsu (Google)