From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761106Ab3BJT5M (ORCPT ); Sun, 10 Feb 2013 14:57:12 -0500 Received: from e7.ny.us.ibm.com ([32.97.182.137]:40864 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756680Ab3BJT5J (ORCPT ); Sun, 10 Feb 2013 14:57:09 -0500 Date: Sun, 10 Feb 2013 11:56:39 -0800 From: "Paul E. McKenney" To: "Srivatsa S. Bhat" Cc: tglx@linutronix.de, peterz@infradead.org, tj@kernel.org, oleg@redhat.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org, rostedt@goodmis.org, wangyun@linux.vnet.ibm.com, xiaoguangrong@linux.vnet.ibm.com, rjw@sisk.pl, sbw@mit.edu, fweisbec@gmail.com, linux@arm.linux.org.uk, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 09/45] smp, cpu hotplug: Fix smp_call_function_*() to prevent CPU offline properly Message-ID: <20130210195639.GL2666@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> <20130122073508.13822.12784.stgit@srivatsabhat.in.ibm.com> <20130209000717.GP2666@linux.vnet.ibm.com> <5117F7E9.7070906@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5117F7E9.7070906@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13021019-5806-0000-0000-00001F6C653C Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 11, 2013 at 01:11:29AM +0530, Srivatsa S. Bhat wrote: > On 02/09/2013 05:37 AM, Paul E. McKenney wrote: > > On Tue, Jan 22, 2013 at 01:05:10PM +0530, Srivatsa S. Bhat wrote: > >> Once stop_machine() is gone from the CPU offline path, we won't be able to > >> depend on preempt_disable() to prevent CPUs from going offline from under us. > >> > >> Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline, > >> while invoking from atomic context. > >> > >> Signed-off-by: Srivatsa S. Bhat > > > > Would it make sense for get_online_cpus_atomic() to return the current > > CPU number? > > Hmm, I'm not so sure. I tried to model it after get_online_cpus(), which doesn't > return anything (for other reasons, of course..) > > Moreover, a function name like *_cpu_* returning the CPU number would be intuitive. > But a name such as *_cpus_* (plural) returning a CPU number might appear confusing.. > > And also I don't think it'll make a huge improvement in the callers.. (We might > be better off avoiding an smp_processor_id() if possible, since this function could > be called in very hot paths).. So I don't see a strong case for returning the > CPU number. But let me know if you think it'll still be worth it for some reason... I just noted a lot of two-line code sequences in your patch that would be one line if the CPU number was returned. But I don't feel strongly about it, so if people are OK with the current version, no problem. Thanx, Paul > > Looks good otherwise. > > > > Thank you very much for the detailed review, Paul! > > Regards, > Srivatsa S. Bhat > > > > >> --- > >> > >> kernel/smp.c | 40 ++++++++++++++++++++++++++-------------- > >> 1 file changed, 26 insertions(+), 14 deletions(-) > >> > >> diff --git a/kernel/smp.c b/kernel/smp.c > >> index 29dd40a..f421bcc 100644 > >> --- a/kernel/smp.c > >> +++ b/kernel/smp.c > >> @@ -310,7 +310,8 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info, > >> * prevent preemption and reschedule on another processor, > >> * as well as CPU removal > >> */ > >> - this_cpu = get_cpu(); > >> + get_online_cpus_atomic(); > >> + this_cpu = smp_processor_id(); > >> > >> /* > >> * Can deadlock when called with interrupts disabled. > >> @@ -342,7 +343,7 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info, > >> } > >> } > >> > >> - put_cpu(); > >> + put_online_cpus_atomic(); > >> > >> return err; > >> } > >> @@ -371,8 +372,10 @@ int smp_call_function_any(const struct cpumask *mask, > >> const struct cpumask *nodemask; > >> int ret; > >> > >> + get_online_cpus_atomic(); > >> /* Try for same CPU (cheapest) */ > >> - cpu = get_cpu(); > >> + cpu = smp_processor_id(); > >> + > >> if (cpumask_test_cpu(cpu, mask)) > >> goto call; > >> > >> @@ -388,7 +391,7 @@ int smp_call_function_any(const struct cpumask *mask, > >> cpu = cpumask_any_and(mask, cpu_online_mask); > >> call: > >> ret = smp_call_function_single(cpu, func, info, wait); > >> - put_cpu(); > >> + put_online_cpus_atomic(); > >> return ret; > >> } > >> EXPORT_SYMBOL_GPL(smp_call_function_any); > >> @@ -409,25 +412,28 @@ void __smp_call_function_single(int cpu, struct call_single_data *data, > >> unsigned int this_cpu; > >> unsigned long flags; > >> > >> - this_cpu = get_cpu(); > >> + get_online_cpus_atomic(); > >> + > >> + this_cpu = smp_processor_id(); > >> + > >> /* > >> * Can deadlock when called with interrupts disabled. > >> * We allow cpu's that are not yet online though, as no one else can > >> * send smp call function interrupt to this cpu and as such deadlocks > >> * can't happen. > >> */ > >> - WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait && irqs_disabled() > >> + WARN_ON_ONCE(cpu_online(this_cpu) && wait && irqs_disabled() > >> && !oops_in_progress); > >> > >> if (cpu == this_cpu) { > >> local_irq_save(flags); > >> data->func(data->info); > >> local_irq_restore(flags); > >> - } else { > >> + } else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) { > >> csd_lock(data); > >> generic_exec_single(cpu, data, wait); > >> } > >> - put_cpu(); > >> + put_online_cpus_atomic(); > >> } > >> > >> /** > >> @@ -451,6 +457,8 @@ void smp_call_function_many(const struct cpumask *mask, > >> unsigned long flags; > >> int refs, cpu, next_cpu, this_cpu = smp_processor_id(); > >> > >> + get_online_cpus_atomic(); > >> + > >> /* > >> * Can deadlock when called with interrupts disabled. > >> * We allow cpu's that are not yet online though, as no one else can > >> @@ -467,17 +475,18 @@ void smp_call_function_many(const struct cpumask *mask, > >> > >> /* No online cpus? We're done. */ > >> if (cpu >= nr_cpu_ids) > >> - return; > >> + goto out_unlock; > >> > >> /* Do we have another CPU which isn't us? */ > >> next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask); > >> if (next_cpu == this_cpu) > >> - next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask); > >> + next_cpu = cpumask_next_and(next_cpu, mask, > >> + cpu_online_mask); > >> > >> /* Fastpath: do that cpu by itself. */ > >> if (next_cpu >= nr_cpu_ids) { > >> smp_call_function_single(cpu, func, info, wait); > >> - return; > >> + goto out_unlock; > >> } > >> > >> data = &__get_cpu_var(cfd_data); > >> @@ -523,7 +532,7 @@ void smp_call_function_many(const struct cpumask *mask, > >> /* Some callers race with other cpus changing the passed mask */ > >> if (unlikely(!refs)) { > >> csd_unlock(&data->csd); > >> - return; > >> + goto out_unlock; > >> } > >> > >> raw_spin_lock_irqsave(&call_function.lock, flags); > >> @@ -554,6 +563,9 @@ void smp_call_function_many(const struct cpumask *mask, > >> /* Optionally wait for the CPUs to complete */ > >> if (wait) > >> csd_lock_wait(&data->csd); > >> + > >> +out_unlock: > >> + put_online_cpus_atomic(); > >> } > >> EXPORT_SYMBOL(smp_call_function_many); > >> > >> @@ -574,9 +586,9 @@ EXPORT_SYMBOL(smp_call_function_many); > >> */ > >> int smp_call_function(smp_call_func_t func, void *info, int wait) > >> { > >> - preempt_disable(); > >> + get_online_cpus_atomic(); > >> smp_call_function_many(cpu_online_mask, func, info, wait); > >> - preempt_enable(); > >> + put_online_cpus_atomic(); > >> > >> return 0; > >> } > >> > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e34.co.us.ibm.com (e34.co.us.ibm.com [32.97.110.152]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e34.co.us.ibm.com", Issuer "GeoTrust SSL CA" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 594AC2C02BB for ; Mon, 11 Feb 2013 06:56:50 +1100 (EST) Received: from /spool/local by e34.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Sun, 10 Feb 2013 12:56:47 -0700 Received: from d03relay05.boulder.ibm.com (d03relay05.boulder.ibm.com [9.17.195.107]) by d03dlp02.boulder.ibm.com (Postfix) with ESMTP id D50B93E4003E for ; Sun, 10 Feb 2013 12:56:36 -0700 (MST) Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay05.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r1AJuift186048 for ; Sun, 10 Feb 2013 12:56:44 -0700 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r1AJugsd028134 for ; Sun, 10 Feb 2013 12:56:44 -0700 Date: Sun, 10 Feb 2013 11:56:39 -0800 From: "Paul E. McKenney" To: "Srivatsa S. Bhat" Subject: Re: [PATCH v5 09/45] smp, cpu hotplug: Fix smp_call_function_*() to prevent CPU offline properly Message-ID: <20130210195639.GL2666@linux.vnet.ibm.com> References: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> <20130122073508.13822.12784.stgit@srivatsabhat.in.ibm.com> <20130209000717.GP2666@linux.vnet.ibm.com> <5117F7E9.7070906@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <5117F7E9.7070906@linux.vnet.ibm.com> Cc: linux-doc@vger.kernel.org, peterz@infradead.org, fweisbec@gmail.com, linux-kernel@vger.kernel.org, mingo@kernel.org, linux-arch@vger.kernel.org, linux@arm.linux.org.uk, xiaoguangrong@linux.vnet.ibm.com, wangyun@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, rusty@rustcorp.com.au, rostedt@goodmis.org, rjw@sisk.pl, namhyung@kernel.org, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org, oleg@redhat.com, sbw@mit.edu, tj@kernel.org, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org Reply-To: paulmck@linux.vnet.ibm.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, Feb 11, 2013 at 01:11:29AM +0530, Srivatsa S. Bhat wrote: > On 02/09/2013 05:37 AM, Paul E. McKenney wrote: > > On Tue, Jan 22, 2013 at 01:05:10PM +0530, Srivatsa S. Bhat wrote: > >> Once stop_machine() is gone from the CPU offline path, we won't be able to > >> depend on preempt_disable() to prevent CPUs from going offline from under us. > >> > >> Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline, > >> while invoking from atomic context. > >> > >> Signed-off-by: Srivatsa S. Bhat > > > > Would it make sense for get_online_cpus_atomic() to return the current > > CPU number? > > Hmm, I'm not so sure. I tried to model it after get_online_cpus(), which doesn't > return anything (for other reasons, of course..) > > Moreover, a function name like *_cpu_* returning the CPU number would be intuitive. > But a name such as *_cpus_* (plural) returning a CPU number might appear confusing.. > > And also I don't think it'll make a huge improvement in the callers.. (We might > be better off avoiding an smp_processor_id() if possible, since this function could > be called in very hot paths).. So I don't see a strong case for returning the > CPU number. But let me know if you think it'll still be worth it for some reason... I just noted a lot of two-line code sequences in your patch that would be one line if the CPU number was returned. But I don't feel strongly about it, so if people are OK with the current version, no problem. Thanx, Paul > > Looks good otherwise. > > > > Thank you very much for the detailed review, Paul! > > Regards, > Srivatsa S. Bhat > > > > >> --- > >> > >> kernel/smp.c | 40 ++++++++++++++++++++++++++-------------- > >> 1 file changed, 26 insertions(+), 14 deletions(-) > >> > >> diff --git a/kernel/smp.c b/kernel/smp.c > >> index 29dd40a..f421bcc 100644 > >> --- a/kernel/smp.c > >> +++ b/kernel/smp.c > >> @@ -310,7 +310,8 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info, > >> * prevent preemption and reschedule on another processor, > >> * as well as CPU removal > >> */ > >> - this_cpu = get_cpu(); > >> + get_online_cpus_atomic(); > >> + this_cpu = smp_processor_id(); > >> > >> /* > >> * Can deadlock when called with interrupts disabled. > >> @@ -342,7 +343,7 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info, > >> } > >> } > >> > >> - put_cpu(); > >> + put_online_cpus_atomic(); > >> > >> return err; > >> } > >> @@ -371,8 +372,10 @@ int smp_call_function_any(const struct cpumask *mask, > >> const struct cpumask *nodemask; > >> int ret; > >> > >> + get_online_cpus_atomic(); > >> /* Try for same CPU (cheapest) */ > >> - cpu = get_cpu(); > >> + cpu = smp_processor_id(); > >> + > >> if (cpumask_test_cpu(cpu, mask)) > >> goto call; > >> > >> @@ -388,7 +391,7 @@ int smp_call_function_any(const struct cpumask *mask, > >> cpu = cpumask_any_and(mask, cpu_online_mask); > >> call: > >> ret = smp_call_function_single(cpu, func, info, wait); > >> - put_cpu(); > >> + put_online_cpus_atomic(); > >> return ret; > >> } > >> EXPORT_SYMBOL_GPL(smp_call_function_any); > >> @@ -409,25 +412,28 @@ void __smp_call_function_single(int cpu, struct call_single_data *data, > >> unsigned int this_cpu; > >> unsigned long flags; > >> > >> - this_cpu = get_cpu(); > >> + get_online_cpus_atomic(); > >> + > >> + this_cpu = smp_processor_id(); > >> + > >> /* > >> * Can deadlock when called with interrupts disabled. > >> * We allow cpu's that are not yet online though, as no one else can > >> * send smp call function interrupt to this cpu and as such deadlocks > >> * can't happen. > >> */ > >> - WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait && irqs_disabled() > >> + WARN_ON_ONCE(cpu_online(this_cpu) && wait && irqs_disabled() > >> && !oops_in_progress); > >> > >> if (cpu == this_cpu) { > >> local_irq_save(flags); > >> data->func(data->info); > >> local_irq_restore(flags); > >> - } else { > >> + } else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) { > >> csd_lock(data); > >> generic_exec_single(cpu, data, wait); > >> } > >> - put_cpu(); > >> + put_online_cpus_atomic(); > >> } > >> > >> /** > >> @@ -451,6 +457,8 @@ void smp_call_function_many(const struct cpumask *mask, > >> unsigned long flags; > >> int refs, cpu, next_cpu, this_cpu = smp_processor_id(); > >> > >> + get_online_cpus_atomic(); > >> + > >> /* > >> * Can deadlock when called with interrupts disabled. > >> * We allow cpu's that are not yet online though, as no one else can > >> @@ -467,17 +475,18 @@ void smp_call_function_many(const struct cpumask *mask, > >> > >> /* No online cpus? We're done. */ > >> if (cpu >= nr_cpu_ids) > >> - return; > >> + goto out_unlock; > >> > >> /* Do we have another CPU which isn't us? */ > >> next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask); > >> if (next_cpu == this_cpu) > >> - next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask); > >> + next_cpu = cpumask_next_and(next_cpu, mask, > >> + cpu_online_mask); > >> > >> /* Fastpath: do that cpu by itself. */ > >> if (next_cpu >= nr_cpu_ids) { > >> smp_call_function_single(cpu, func, info, wait); > >> - return; > >> + goto out_unlock; > >> } > >> > >> data = &__get_cpu_var(cfd_data); > >> @@ -523,7 +532,7 @@ void smp_call_function_many(const struct cpumask *mask, > >> /* Some callers race with other cpus changing the passed mask */ > >> if (unlikely(!refs)) { > >> csd_unlock(&data->csd); > >> - return; > >> + goto out_unlock; > >> } > >> > >> raw_spin_lock_irqsave(&call_function.lock, flags); > >> @@ -554,6 +563,9 @@ void smp_call_function_many(const struct cpumask *mask, > >> /* Optionally wait for the CPUs to complete */ > >> if (wait) > >> csd_lock_wait(&data->csd); > >> + > >> +out_unlock: > >> + put_online_cpus_atomic(); > >> } > >> EXPORT_SYMBOL(smp_call_function_many); > >> > >> @@ -574,9 +586,9 @@ EXPORT_SYMBOL(smp_call_function_many); > >> */ > >> int smp_call_function(smp_call_func_t func, void *info, int wait) > >> { > >> - preempt_disable(); > >> + get_online_cpus_atomic(); > >> smp_call_function_many(cpu_online_mask, func, info, wait); > >> - preempt_enable(); > >> + put_online_cpus_atomic(); > >> > >> return 0; > >> } > >> > From mboxrd@z Thu Jan 1 00:00:00 1970 From: paulmck@linux.vnet.ibm.com (Paul E. McKenney) Date: Sun, 10 Feb 2013 11:56:39 -0800 Subject: [PATCH v5 09/45] smp, cpu hotplug: Fix smp_call_function_*() to prevent CPU offline properly In-Reply-To: <5117F7E9.7070906@linux.vnet.ibm.com> References: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> <20130122073508.13822.12784.stgit@srivatsabhat.in.ibm.com> <20130209000717.GP2666@linux.vnet.ibm.com> <5117F7E9.7070906@linux.vnet.ibm.com> Message-ID: <20130210195639.GL2666@linux.vnet.ibm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Feb 11, 2013 at 01:11:29AM +0530, Srivatsa S. Bhat wrote: > On 02/09/2013 05:37 AM, Paul E. McKenney wrote: > > On Tue, Jan 22, 2013 at 01:05:10PM +0530, Srivatsa S. Bhat wrote: > >> Once stop_machine() is gone from the CPU offline path, we won't be able to > >> depend on preempt_disable() to prevent CPUs from going offline from under us. > >> > >> Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline, > >> while invoking from atomic context. > >> > >> Signed-off-by: Srivatsa S. Bhat > > > > Would it make sense for get_online_cpus_atomic() to return the current > > CPU number? > > Hmm, I'm not so sure. I tried to model it after get_online_cpus(), which doesn't > return anything (for other reasons, of course..) > > Moreover, a function name like *_cpu_* returning the CPU number would be intuitive. > But a name such as *_cpus_* (plural) returning a CPU number might appear confusing.. > > And also I don't think it'll make a huge improvement in the callers.. (We might > be better off avoiding an smp_processor_id() if possible, since this function could > be called in very hot paths).. So I don't see a strong case for returning the > CPU number. But let me know if you think it'll still be worth it for some reason... I just noted a lot of two-line code sequences in your patch that would be one line if the CPU number was returned. But I don't feel strongly about it, so if people are OK with the current version, no problem. Thanx, Paul > > Looks good otherwise. > > > > Thank you very much for the detailed review, Paul! > > Regards, > Srivatsa S. Bhat > > > > >> --- > >> > >> kernel/smp.c | 40 ++++++++++++++++++++++++++-------------- > >> 1 file changed, 26 insertions(+), 14 deletions(-) > >> > >> diff --git a/kernel/smp.c b/kernel/smp.c > >> index 29dd40a..f421bcc 100644 > >> --- a/kernel/smp.c > >> +++ b/kernel/smp.c > >> @@ -310,7 +310,8 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info, > >> * prevent preemption and reschedule on another processor, > >> * as well as CPU removal > >> */ > >> - this_cpu = get_cpu(); > >> + get_online_cpus_atomic(); > >> + this_cpu = smp_processor_id(); > >> > >> /* > >> * Can deadlock when called with interrupts disabled. > >> @@ -342,7 +343,7 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info, > >> } > >> } > >> > >> - put_cpu(); > >> + put_online_cpus_atomic(); > >> > >> return err; > >> } > >> @@ -371,8 +372,10 @@ int smp_call_function_any(const struct cpumask *mask, > >> const struct cpumask *nodemask; > >> int ret; > >> > >> + get_online_cpus_atomic(); > >> /* Try for same CPU (cheapest) */ > >> - cpu = get_cpu(); > >> + cpu = smp_processor_id(); > >> + > >> if (cpumask_test_cpu(cpu, mask)) > >> goto call; > >> > >> @@ -388,7 +391,7 @@ int smp_call_function_any(const struct cpumask *mask, > >> cpu = cpumask_any_and(mask, cpu_online_mask); > >> call: > >> ret = smp_call_function_single(cpu, func, info, wait); > >> - put_cpu(); > >> + put_online_cpus_atomic(); > >> return ret; > >> } > >> EXPORT_SYMBOL_GPL(smp_call_function_any); > >> @@ -409,25 +412,28 @@ void __smp_call_function_single(int cpu, struct call_single_data *data, > >> unsigned int this_cpu; > >> unsigned long flags; > >> > >> - this_cpu = get_cpu(); > >> + get_online_cpus_atomic(); > >> + > >> + this_cpu = smp_processor_id(); > >> + > >> /* > >> * Can deadlock when called with interrupts disabled. > >> * We allow cpu's that are not yet online though, as no one else can > >> * send smp call function interrupt to this cpu and as such deadlocks > >> * can't happen. > >> */ > >> - WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait && irqs_disabled() > >> + WARN_ON_ONCE(cpu_online(this_cpu) && wait && irqs_disabled() > >> && !oops_in_progress); > >> > >> if (cpu == this_cpu) { > >> local_irq_save(flags); > >> data->func(data->info); > >> local_irq_restore(flags); > >> - } else { > >> + } else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) { > >> csd_lock(data); > >> generic_exec_single(cpu, data, wait); > >> } > >> - put_cpu(); > >> + put_online_cpus_atomic(); > >> } > >> > >> /** > >> @@ -451,6 +457,8 @@ void smp_call_function_many(const struct cpumask *mask, > >> unsigned long flags; > >> int refs, cpu, next_cpu, this_cpu = smp_processor_id(); > >> > >> + get_online_cpus_atomic(); > >> + > >> /* > >> * Can deadlock when called with interrupts disabled. > >> * We allow cpu's that are not yet online though, as no one else can > >> @@ -467,17 +475,18 @@ void smp_call_function_many(const struct cpumask *mask, > >> > >> /* No online cpus? We're done. */ > >> if (cpu >= nr_cpu_ids) > >> - return; > >> + goto out_unlock; > >> > >> /* Do we have another CPU which isn't us? */ > >> next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask); > >> if (next_cpu == this_cpu) > >> - next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask); > >> + next_cpu = cpumask_next_and(next_cpu, mask, > >> + cpu_online_mask); > >> > >> /* Fastpath: do that cpu by itself. */ > >> if (next_cpu >= nr_cpu_ids) { > >> smp_call_function_single(cpu, func, info, wait); > >> - return; > >> + goto out_unlock; > >> } > >> > >> data = &__get_cpu_var(cfd_data); > >> @@ -523,7 +532,7 @@ void smp_call_function_many(const struct cpumask *mask, > >> /* Some callers race with other cpus changing the passed mask */ > >> if (unlikely(!refs)) { > >> csd_unlock(&data->csd); > >> - return; > >> + goto out_unlock; > >> } > >> > >> raw_spin_lock_irqsave(&call_function.lock, flags); > >> @@ -554,6 +563,9 @@ void smp_call_function_many(const struct cpumask *mask, > >> /* Optionally wait for the CPUs to complete */ > >> if (wait) > >> csd_lock_wait(&data->csd); > >> + > >> +out_unlock: > >> + put_online_cpus_atomic(); > >> } > >> EXPORT_SYMBOL(smp_call_function_many); > >> > >> @@ -574,9 +586,9 @@ EXPORT_SYMBOL(smp_call_function_many); > >> */ > >> int smp_call_function(smp_call_func_t func, void *info, int wait) > >> { > >> - preempt_disable(); > >> + get_online_cpus_atomic(); > >> smp_call_function_many(cpu_online_mask, func, info, wait); > >> - preempt_enable(); > >> + put_online_cpus_atomic(); > >> > >> return 0; > >> } > >> >