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McKenney" To: Tony Lindgren Subject: Re: [PATCH] ARM: OMAP2+: Fix suspcious RCU usage splats for omap_enter_idle_coupled Message-ID: <20210108190716.GV2743@paulmck-ThinkPad-P72> References: <20210108134105.58543-1-tony@atomide.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210108134105.58543-1-tony@atomide.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210108_140717_743702_6A80B9CE X-CRM114-Status: GOOD ( 22.29 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: paulmck@kernel.org Cc: Russell King , linux-omap@vger.kernel.org, Daniel Lezcano , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jan 08, 2021 at 03:41:05PM +0200, Tony Lindgren wrote: > We get suspcious RCU usage splats with cpuidle in several places in > omap_enter_idle_coupled() with the kernel debug options enabled: > > RCU used illegally from extended quiescent state! > ... > (_raw_spin_lock_irqsave) > (omap_enter_idle_coupled+0x17c/0x2d8) > (omap_enter_idle_coupled) > (cpuidle_enter_state) > (cpuidle_enter_state_coupled) > (cpuidle_enter) > > Let's use RCU_NONIDLE to suppress these splats. Things got changed around > with commit 1098582a0f6c ("sched,idle,rcu: Push rcu_idle deeper into the > idle path") that started triggering these warnings. > > For the tick_broadcast related calls, ideally we'd just switch over to > using CPUIDLE_FLAG_TIMER_STOP for omap_enter_idle_coupled() to have the > generic cpuidle code handle the tick_broadcast related calls for us and > then just drop the tick_broadcast calls here. > > But we're currently missing the call in the common cpuidle code for > tick_broadcast_enable() that CPU1 hotplug needs as described in earlier > commit 50d6b3cf9403 ("ARM: OMAP2+: fix lack of timer interrupts on CPU1 > after hotplug"). > > Cc: Daniel Lezcano > Cc: Paul E. McKenney > Cc: Russell King > Signed-off-by: Tony Lindgren >From an RCU viewpoint: Acked-by: Paul E. McKenney > --- > arch/arm/mach-omap2/cpuidle44xx.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/arch/arm/mach-omap2/cpuidle44xx.c b/arch/arm/mach-omap2/cpuidle44xx.c > --- a/arch/arm/mach-omap2/cpuidle44xx.c > +++ b/arch/arm/mach-omap2/cpuidle44xx.c > @@ -151,10 +151,10 @@ static int omap_enter_idle_coupled(struct cpuidle_device *dev, > (cx->mpu_logic_state == PWRDM_POWER_OFF); > > /* Enter broadcast mode for periodic timers */ > - tick_broadcast_enable(); > + RCU_NONIDLE(tick_broadcast_enable()); > > /* Enter broadcast mode for one-shot timers */ > - tick_broadcast_enter(); > + RCU_NONIDLE(tick_broadcast_enter()); > > /* > * Call idle CPU PM enter notifier chain so that > @@ -166,7 +166,7 @@ static int omap_enter_idle_coupled(struct cpuidle_device *dev, > > if (dev->cpu == 0) { > pwrdm_set_logic_retst(mpu_pd, cx->mpu_logic_state); > - omap_set_pwrdm_state(mpu_pd, cx->mpu_state); > + RCU_NONIDLE(omap_set_pwrdm_state(mpu_pd, cx->mpu_state)); > > /* > * Call idle CPU cluster PM enter notifier chain > @@ -179,7 +179,7 @@ static int omap_enter_idle_coupled(struct cpuidle_device *dev, > index = 1; > cx = state_ptr + index; > pwrdm_set_logic_retst(mpu_pd, cx->mpu_logic_state); > - omap_set_pwrdm_state(mpu_pd, cx->mpu_state); > + RCU_NONIDLE(omap_set_pwrdm_state(mpu_pd, cx->mpu_state)); > mpuss_can_lose_context = 0; > } > } > @@ -195,9 +195,9 @@ static int omap_enter_idle_coupled(struct cpuidle_device *dev, > mpuss_can_lose_context) > gic_dist_disable(); > > - clkdm_deny_idle(cpu_clkdm[1]); > - omap_set_pwrdm_state(cpu_pd[1], PWRDM_POWER_ON); > - clkdm_allow_idle(cpu_clkdm[1]); > + RCU_NONIDLE(clkdm_deny_idle(cpu_clkdm[1])); > + RCU_NONIDLE(omap_set_pwrdm_state(cpu_pd[1], PWRDM_POWER_ON)); > + RCU_NONIDLE(clkdm_allow_idle(cpu_clkdm[1])); > > if (IS_PM44XX_ERRATUM(PM_OMAP4_ROM_SMP_BOOT_ERRATUM_GICD) && > mpuss_can_lose_context) { > @@ -225,7 +225,7 @@ static int omap_enter_idle_coupled(struct cpuidle_device *dev, > cpu_pm_exit(); > > cpu_pm_out: > - tick_broadcast_exit(); > + RCU_NONIDLE(tick_broadcast_exit()); > > fail: > cpuidle_coupled_parallel_barrier(dev, &abort_barrier); > -- > 2.30.0 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel