From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mukesh Ojha Subject: Re: [PATCH] cpu/hotplug: Fix rollback during error-out in takedown_cpu() Date: Tue, 4 Sep 2018 17:42:28 +0530 Message-ID: <26a4e734-088c-dbd7-30d2-34065787e925@codeaurora.org> References: <1536042803-6152-1-git-send-email-neeraju@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1536042803-6152-1-git-send-email-neeraju@codeaurora.org> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Neeraj Upadhyay , tglx@linutronix.de, josh@joshtriplett.org, peterz@infradead.org, mingo@kernel.org, jiangshanlai@gmail.com, dzickus@redhat.com, brendan.jackman@arm.com, malat@debian.org Cc: linux-kernel@vger.kernel.org, sramana@codeaurora.org, linux-arm-msm@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org On 9/4/2018 12:03 PM, Neeraj Upadhyay wrote: > If takedown_cpu() fails during _cpu_down(), st->state is reset, > by calling cpuhp_reset_state(). This results in an additional > increment of st->state, which results in CPUHP_AP_SMPBOOT_THREADS > state being skipped during rollback. Fix this by not calling > cpuhp_reset_state() and doing the state reset directly in > _cpu_down(). > > Fixes: 4dddfb5faa61 ("smp/hotplug: Rewrite AP state machine core") > Signed-off-by: Neeraj Upadhyay > --- > kernel/cpu.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/kernel/cpu.c b/kernel/cpu.c > index aa7fe85..9f49edb 100644 > --- a/kernel/cpu.c > +++ b/kernel/cpu.c > @@ -970,7 +970,14 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, > */ > ret = cpuhp_down_callbacks(cpu, st, target); > if (ret && st->state > CPUHP_TEARDOWN_CPU && st->state < prev_state) { > - cpuhp_reset_state(st, prev_state); > + /* > + * As st->last is not set, cpuhp_reset_state() increments > + * st->state, which results in CPUHP_AP_SMPBOOT_THREADS being > + * skipped during rollback. So, don't use it here. > + */ > + st->rollback = true; > + st->target = prev_state; > + st->bringup = !st->bringup; Acked-by: Mukesh Ojha looks valid for this case. > __cpuhp_kick_ap(st); > } >