From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754149AbbKQQJ0 (ORCPT ); Tue, 17 Nov 2015 11:09:26 -0500 Received: from mx1.redhat.com ([209.132.183.28]:34142 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751903AbbKQQJY (ORCPT ); Tue, 17 Nov 2015 11:09:24 -0500 Date: Tue, 17 Nov 2015 18:05:23 +0100 From: Oleg Nesterov To: Ingo Molnar , Peter Zijlstra Cc: Milos Vyletel , Prarit Bhargava , Tejun Heo , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: [PATCH v2 3/8] stop_machine: make cpu_stop_queue_work() and stop_one_cpu_nowait() return bool Message-ID: <20151117170523.GA13955@redhat.com> References: <20151115193254.GA8225@redhat.com> <20151115193317.GA8252@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151115193317.GA8252@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/15, Oleg Nesterov wrote: > > --- a/include/linux/stop_machine.h > +++ b/include/linux/stop_machine.h > @@ -29,7 +29,7 @@ struct cpu_stop_work { > > int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg); > int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *arg); > -void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, > +bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, > struct cpu_stop_work *work_buf); Peter, sorry!!! I forgot to update the !CONFIG_SMP version of stop_one_cpu_nowait(). Please see V2 below. Or please tell me if I should send the incremental patch: --- a/include/linux/stop_machine.h +++ b/include/linux/stop_machine.h @@ -65,7 +65,7 @@ static void stop_one_cpu_nowait_workfn(struct work_struct *work) preempt_enable(); } -static inline void stop_one_cpu_nowait(unsigned int cpu, +static inline bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, struct cpu_stop_work *work_buf) { @@ -74,7 +74,10 @@ static inline void stop_one_cpu_nowait(unsigned int cpu, work_buf->fn = fn; work_buf->arg = arg; schedule_work(&work_buf->work); + return true; } + + return false; } ------------------------------------------------------------------------------- >>From d5710e2dca493046257f97ed18699eed4c36a880 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sat, 14 Nov 2015 19:37:01 +0100 Subject: [PATCH v2 3/8] stop_machine: make cpu_stop_queue_work() and stop_one_cpu_nowait() return bool Change cpu_stop_queue_work() to return true if the work was queued and change stop_one_cpu_nowait() to return the result of cpu_stop_queue_work(). This makes it more useful, for example now you can alloc cpu_stop_work for stop_one_cpu_nowait() and free it in the callback or if stop_one_cpu_nowait() fails, currently this is impossible because you can't know if @fn will be called or not. Also, this allows to kill cpu_stop_done->executed, see the next changes. Signed-off-by: Oleg Nesterov --- include/linux/stop_machine.h | 7 +++++-- kernel/stop_machine.c | 16 ++++++++++++---- 2 files changed, 17 insertions(+), 6 deletions(-) diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h index 0adedca..9ef42e1 100644 --- a/include/linux/stop_machine.h +++ b/include/linux/stop_machine.h @@ -29,7 +29,7 @@ struct cpu_stop_work { int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg); int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *arg); -void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, +bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, struct cpu_stop_work *work_buf); int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); @@ -65,7 +65,7 @@ static void stop_one_cpu_nowait_workfn(struct work_struct *work) preempt_enable(); } -static inline void stop_one_cpu_nowait(unsigned int cpu, +static inline bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, struct cpu_stop_work *work_buf) { @@ -74,7 +74,10 @@ static inline void stop_one_cpu_nowait(unsigned int cpu, work_buf->fn = fn; work_buf->arg = arg; schedule_work(&work_buf->work); + return true; } + + return false; } static inline int stop_cpus(const struct cpumask *cpumask, diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 17f01a9..0ec1f16 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -81,17 +81,21 @@ static void __cpu_stop_queue_work(struct cpu_stopper *stopper, } /* queue @work to @stopper. if offline, @work is completed immediately */ -static void cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work) +static bool cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work) { struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu); unsigned long flags; + bool enabled; spin_lock_irqsave(&stopper->lock, flags); - if (stopper->enabled) + enabled = stopper->enabled; + if (enabled) __cpu_stop_queue_work(stopper, work); else cpu_stop_signal_done(work->done, false); spin_unlock_irqrestore(&stopper->lock, flags); + + return enabled; } /** @@ -297,12 +301,16 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void * * * CONTEXT: * Don't care. + * + * RETURNS: + * true if cpu_stop_work was queued successfully and @fn will be called, + * false otherwise. */ -void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, +bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, struct cpu_stop_work *work_buf) { *work_buf = (struct cpu_stop_work){ .fn = fn, .arg = arg, }; - cpu_stop_queue_work(cpu, work_buf); + return cpu_stop_queue_work(cpu, work_buf); } /* static data for stop_cpus */ -- 1.5.5.1