Re: [PATCH 15/36] cpuidle,cpu_pm: Remove RCU fiddling from cpu_pm_{enter,exit}()
From: Peter Zijlstra <peterz@infradead.org>
Date: 2022-06-14 16:42:42
Also in:
linux-acpi, linux-alpha, linux-arch, linux-arm-msm, linux-clk, linux-m68k, linux-mips, linux-omap, linux-perf-users, linux-pm, linux-riscv, linux-s390, linux-sh, linux-tegra, linux-um, linuxppc-dev, lkml, rcu, sparclinux, xen-devel
On Tue, Jun 14, 2022 at 05:13:16PM +0100, Mark Rutland wrote:
On Wed, Jun 08, 2022 at 04:27:38PM +0200, Peter Zijlstra wrote:quoted
All callers should still have RCU enabled.IIUC with that true we should be able to drop the RCU_NONIDLE() from drivers/perf/arm_pmu.c, as we only needed that for an invocation via a pm notifier. I should be able to give that a spin on some hardware.quoted
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- kernel/cpu_pm.c | 9 --------- 1 file changed, 9 deletions(-)--- a/kernel/cpu_pm.c +++ b/kernel/cpu_pm.c@@ -30,16 +30,9 @@ static int cpu_pm_notify(enum cpu_pm_eve { int ret; - /* - * This introduces a RCU read critical section, which could be - * disfunctional in cpu idle. Copy RCU_NONIDLE code to let RCU know - * this. - */ - rcu_irq_enter_irqson(); rcu_read_lock(); ret = raw_notifier_call_chain(&cpu_pm_notifier.chain, event, NULL); rcu_read_unlock(); - rcu_irq_exit_irqson();To make this easier to debug, is it worth adding an assertion that RCU is watching here? e.g. RCU_LOCKDEP_WARN(!rcu_is_watching(), "cpu_pm_notify() used illegally from EQS");
My understanding is that rcu_read_lock() implies something along those lines when PROVE_RCU. _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization