From: "Paul E. McKenney" <paulmck@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
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Subject: Re: [PATCH 16/36] rcu: Fix rcu_idle_exit()
Date: Tue, 14 Jun 2022 17:44:12 -0700 [thread overview]
Message-ID: <20220615004412.GA5766@paulmck-ThinkPad-P17-Gen-1> (raw)
In-Reply-To: <20220608144516.935970247@infradead.org>
, Arnd Bergmann <arnd@arndb.de>, ulli.kroll@googlemail.com, vgupta@kernel.org, linux-clk@vger.kernel.org, josh@joshtriplett.org, rostedt@goodmis.org, rcu@vger.kernel.org, bp@alien8.de, bcain@quicinc.com, tsbogend@alpha.franken.de, linux-parisc@vger.kernel.org, sudeep.holla@arm.com, shawnguo@kernel.org, davem@davemloft.net, dalias@libc.org, tony@atomide.com, amakhalov@vmware.com, bjorn.andersson@linaro.org, hpa@zytor.com, sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-riscv@lists.infradead.org, anton.ivanov@cambridgegreys.com, jonas@southpole.se, yury.norov@gmail.com, richard@nod.at, x86@kernel.org, linux@armlinux.org.uk, mingo@redhat.com, aou@eecs.berkeley.edu, hca@linux.ibm.com, stefan.kristiansson@saunalahti.fi, openrisc@lists.librecores.org, paul.walmsley@sifive.com, linux-tegra@vger.kernel.org, namhyung@kernel.org, andriy.shevchenko@linux.intel.com, jpoimboe@kernel.org, jgross@suse.com, monstr@monstr.eu, linux-mips@vger.kernel.org, palmer@dabbelt.com, anup@brain
fault.org, ink@jurassic.park.msu.ru, johannes@sipsolutions.net, linuxppc-dev@lists.ozlabs.org
Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org
Sender: "Linuxppc-dev" <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org>
On Wed, Jun 08, 2022 at 04:27:39PM +0200, Peter Zijlstra wrote:
> Current rcu_idle_exit() is terminally broken because it uses
> local_irq_{save,restore}(), which are traced which uses RCU.
>
> However, now that all the callers are sure to have IRQs disabled, we
> can remove these calls.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Acked-by: Paul E. McKenney <paulmck@kernel.org>
We have some fun conflicts between this series and Frederic's context-tracking
series. But it looks like these can be resolved by:
1. A patch on top of Frederic's series that provides the old rcu_*()
names for the functions now prefixed with ct_*() such as
ct_idle_exit().
2. Another patch on top of Frederic's series that takes the
changes remaining from this patch, shown below. Frederic's
series uses raw_local_irq_save() and raw_local_irq_restore(),
which can then be removed.
Or is there a better way to do this?
Thanx, Paul
------------------------------------------------------------------------
commit f64cee8c159e9863a74594efe3d33fb513a6a7b5
Author: Peter Zijlstra <peterz@infradead.org>
Date: Tue Jun 14 17:24:43 2022 -0700
context_tracking: Interrupts always disabled for ct_idle_exit()
Now that the idle-loop cleanups have ensured that rcu_idle_exit() is
always invoked with interrupts disabled, remove the interrupt disabling
in favor of a debug check.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 1da44803fd319..99310cf5b0254 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -332,11 +332,8 @@ EXPORT_SYMBOL_GPL(ct_idle_enter);
*/
void noinstr ct_idle_exit(void)
{
- unsigned long flags;
-
- raw_local_irq_save(flags);
+ WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled());
ct_kernel_enter(false, RCU_DYNTICKS_IDX - CONTEXT_IDLE);
- raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(ct_idle_exit);
next prev parent reply other threads:[~2022-06-16 1:55 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-08 14:27 [PATCH 00/36] cpuidle,rcu: Cleanup the mess Peter Zijlstra
2022-06-08 14:27 ` [PATCH 01/36] x86/perf/amd: Remove tracing from perf_lopwr_cb() Peter Zijlstra
2022-06-08 14:27 ` [PATCH 02/36] x86/idle: Replace x86_idle with a static_call Peter Zijlstra
2022-06-08 18:13 ` Rafael J. Wysocki
2022-06-08 14:27 ` [PATCH 03/36] cpuidle/poll: Ensure IRQ state is invariant Peter Zijlstra
2022-07-06 13:51 ` Rafael J. Wysocki
2022-06-08 14:27 ` [PATCH 04/36] cpuidle,intel_idle: Fix CPUIDLE_FLAG_IRQ_ENABLE Peter Zijlstra
2022-06-08 15:01 ` Rafael J. Wysocki
2022-06-08 15:48 ` Peter Zijlstra
2022-06-08 16:08 ` Rafael J. Wysocki
2022-06-09 23:49 ` Jacob Pan
2022-06-13 8:44 ` Peter Zijlstra
2022-06-16 21:26 ` Jacob Pan
2022-07-25 19:43 ` Michel Lespinasse
2022-07-28 17:20 ` Paul E. McKenney
2022-07-29 10:24 ` Michel Lespinasse
2022-07-29 14:59 ` Rafael J. Wysocki
2022-07-30 9:48 ` Michel Lespinasse
2022-07-30 19:52 ` Rafael J. Wysocki
2022-07-30 23:45 ` Michel Lespinasse
2022-07-29 15:26 ` Paul E. McKenney
2022-07-29 15:28 ` Paul E. McKenney
2022-07-30 9:40 ` Michel Lespinasse
2022-07-30 18:16 ` Paul E. McKenney
2022-06-08 14:27 ` [PATCH 05/36] cpuidle: Move IRQ state validation Peter Zijlstra
2022-07-06 13:54 ` Rafael J. Wysocki
2022-06-08 14:27 ` [PATCH 06/36] cpuidle,riscv: Push RCU-idle into driver Peter Zijlstra
2022-06-08 14:27 ` [PATCH 07/36] cpuidle,tegra: " Peter Zijlstra
2022-06-08 14:27 ` [PATCH 08/36] cpuidle,psci: " Peter Zijlstra
2022-06-08 14:27 ` [PATCH 09/36] cpuidle,imx6: " Peter Zijlstra
2022-06-08 14:27 ` [PATCH 10/36] cpuidle,omap3: " Peter Zijlstra
2022-06-13 12:33 ` Tony Lindgren
2022-06-08 14:27 ` [PATCH 11/36] cpuidle,armada: " Peter Zijlstra
2022-06-08 14:27 ` [PATCH 12/36] cpuidle,omap2: " Peter Zijlstra
2022-06-13 12:33 ` Tony Lindgren
2022-06-08 14:27 ` [PATCH 13/36] cpuidle,dt: " Peter Zijlstra
2022-06-08 14:27 ` [PATCH 14/36] cpuidle: Fix rcu_idle_*() usage Peter Zijlstra
2022-06-14 12:41 ` Mark Rutland
2022-06-14 16:40 ` Peter Zijlstra
2022-06-14 16:59 ` Mark Rutland
2022-07-26 9:56 ` Gautham R. Shenoy
2022-06-08 14:27 ` [PATCH 15/36] cpuidle,cpu_pm: Remove RCU fiddling from cpu_pm_{enter,exit}() Peter Zijlstra
2022-06-14 16:13 ` Mark Rutland
2022-06-14 16:42 ` Peter Zijlstra
2022-06-14 16:53 ` Mark Rutland
2022-06-08 14:27 ` [PATCH 16/36] rcu: Fix rcu_idle_exit() Peter Zijlstra
2022-06-14 16:14 ` Mark Rutland
2022-06-15 0:44 ` Paul E. McKenney [this message]
2022-06-08 14:27 ` [PATCH 17/36] acpi_idle: Remove tracing Peter Zijlstra
2022-07-06 13:59 ` Rafael J. Wysocki
2022-06-08 14:27 ` [PATCH 18/36] cpuidle: Annotate poll_idle() Peter Zijlstra
2022-07-06 14:00 ` Rafael J. Wysocki
2022-06-08 14:27 ` [PATCH 19/36] objtool/idle: Validate __cpuidle code as noinstr Peter Zijlstra
2022-07-06 9:46 ` Geert Uytterhoeven
2022-06-08 14:27 ` [PATCH 20/36] arch/idle: Change arch_cpu_idle() IRQ behaviour Peter Zijlstra
2022-06-08 16:22 ` Arnd Bergmann
2022-06-14 16:22 ` Mark Rutland
2022-07-06 14:02 ` Rafael J. Wysocki
2022-06-08 14:27 ` [PATCH 21/36] x86/tdx: Remove TDX_HCALL_ISSUE_STI Peter Zijlstra
2022-06-13 8:26 ` Lai Jiangshan
2022-06-13 8:41 ` Peter Zijlstra
2022-06-08 14:27 ` [PATCH 22/36] arm,smp: Remove trace_.*_rcuidle() usage Peter Zijlstra
2022-06-08 14:27 ` [PATCH 23/36] arm64,smp: " Peter Zijlstra
2022-06-14 16:24 ` Mark Rutland
2022-06-15 6:05 ` Marc Zyngier
2022-06-08 14:27 ` [PATCH 24/36] printk: " Peter Zijlstra
2022-06-09 9:16 ` Petr Mladek
2022-06-09 10:02 ` Peter Zijlstra
2022-06-09 11:30 ` Sergey Senozhatsky
2022-06-09 13:02 ` Petr Mladek
2022-06-11 2:33 ` Sergey Senozhatsky
2022-06-14 14:37 ` Steven Rostedt
2022-06-09 13:06 ` Petr Mladek
2022-06-11 2:23 ` Sergey Senozhatsky
2022-06-09 10:14 ` Petr Mladek
2022-06-08 14:27 ` [PATCH 25/36] time/tick-broadcast: Remove RCU_NONIDLE usage Peter Zijlstra
2022-06-14 16:28 ` Mark Rutland
2022-06-08 14:27 ` [PATCH 26/36] cpuidle,sched: Remove annotations from TIF_{POLLING_NRFLAG,NEED_RESCHED} Peter Zijlstra
2022-06-08 14:27 ` [PATCH 27/36] cpuidle,mwait: Make noinstr clean Peter Zijlstra
2022-06-08 14:27 ` [PATCH 28/36] cpuidle,tdx: Make tdx " Peter Zijlstra
2022-06-08 14:27 ` [PATCH 29/36] cpuidle,xenpv: Make more PARAVIRT_XXL " Peter Zijlstra
2022-06-13 18:48 ` Srivatsa S. Bhat
2022-06-13 19:23 ` [Pv-drivers] [PATCH 29/36] cpuidle, xenpv: " Nadav Amit
2022-06-14 16:44 ` Peter Zijlstra
2022-06-08 14:27 ` [PATCH 30/36] cpuidle,nospec: Make " Peter Zijlstra
2022-06-08 14:27 ` [PATCH 31/36] cpuidle,acpi: " Peter Zijlstra
2022-07-06 14:04 ` Rafael J. Wysocki
2022-06-08 14:27 ` [PATCH 32/36] ftrace: WARN on rcuidle Peter Zijlstra
2022-06-08 14:27 ` [PATCH 33/36] cpuidle,omap3: Use WFI for omap3_pm_idle() Peter Zijlstra
2022-06-08 16:28 ` Arnd Bergmann
2022-06-09 7:39 ` Tony Lindgren
2022-06-09 9:47 ` Peter Zijlstra
2022-06-09 9:40 ` Peter Zijlstra
2022-06-13 12:36 ` Tony Lindgren
2022-06-08 14:27 ` [PATCH 34/36] cpuidle,omap3: Push RCU-idle into omap_sram_idle() Peter Zijlstra
2022-06-08 15:04 ` Peter Zijlstra
2022-06-13 12:35 ` Tony Lindgren
2022-06-13 12:39 ` [PATCH 34.5/36] cpuidle,omap4: Push RCU-idle into omap4_enter_lowpower() Tony Lindgren
2022-06-14 22:12 ` Peter Zijlstra
2022-06-15 5:35 ` Tony Lindgren
2022-06-08 14:27 ` [PATCH 35/36] cpuidle,powerdomain: Remove trace_.*_rcuidle() Peter Zijlstra
2022-06-08 14:27 ` [PATCH 36/36] cpuidle,clk: " Peter Zijlstra
2022-06-08 20:03 ` Stephen Boyd
2022-06-14 11:19 ` [PATCH 00/36] cpuidle,rcu: Cleanup the mess Mark Rutland
2022-06-14 16:58 ` Peter Zijlstra
2022-06-14 17:33 ` Mark Rutland
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