From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Srivatsa S. Bhat" Subject: [PATCH v5 17/45] softirq: Use get/put_online_cpus_atomic() to prevent CPU offline Date: Tue, 22 Jan 2013 13:07:43 +0530 Message-ID: <20130122073739.13822.99740.stgit@srivatsabhat.in.ibm.com> References: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> Sender: linux-kernel-owner@vger.kernel.org To: tglx@linutronix.de, peterz@infradead.org, tj@kernel.org, oleg@redhat.com, paulmck@linux.vnet.ibm.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org Cc: 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, srivatsa.bhat@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 List-Id: linux-arch.vger.kernel.org Once stop_machine() is gone from the CPU offline path, we won't be able to depend on preempt_disable() or local_irq_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. Cc: Frederic Weisbecker Signed-off-by: Srivatsa S. Bhat --- kernel/softirq.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/softirq.c b/kernel/softirq.c index ed567ba..98c3e27 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -631,6 +631,7 @@ static void remote_softirq_receive(void *data) static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) { + get_online_cpus_atomic(); if (cpu_online(cpu)) { cp->func = remote_softirq_receive; cp->info = cp; @@ -638,8 +639,10 @@ static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softir cp->priv = softirq; __smp_call_function_single(cpu, cp, 0); + put_online_cpus_atomic(); return 0; } + put_online_cpus_atomic(); return 1; } #else /* CONFIG_USE_GENERIC_SMP_HELPERS */ From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp02.au.ibm.com ([202.81.31.144]:59795 "EHLO e23smtp02.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751077Ab3AVHjq (ORCPT ); Tue, 22 Jan 2013 02:39:46 -0500 Received: from /spool/local by e23smtp02.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 22 Jan 2013 17:34:26 +1000 From: "Srivatsa S. Bhat" Subject: [PATCH v5 17/45] softirq: Use get/put_online_cpus_atomic() to prevent CPU offline Date: Tue, 22 Jan 2013 13:07:43 +0530 Message-ID: <20130122073739.13822.99740.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> References: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: tglx@linutronix.de, peterz@infradead.org, tj@kernel.org, oleg@redhat.com, paulmck@linux.vnet.ibm.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org Cc: 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, srivatsa.bhat@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 Message-ID: <20130122073743.CAq-9cDcj7CB3E_u9kJFaXwIn_BgVrewCGjo0rHpxQM@z> Once stop_machine() is gone from the CPU offline path, we won't be able to depend on preempt_disable() or local_irq_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. Cc: Frederic Weisbecker Signed-off-by: Srivatsa S. Bhat --- kernel/softirq.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/softirq.c b/kernel/softirq.c index ed567ba..98c3e27 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -631,6 +631,7 @@ static void remote_softirq_receive(void *data) static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq) { + get_online_cpus_atomic(); if (cpu_online(cpu)) { cp->func = remote_softirq_receive; cp->info = cp; @@ -638,8 +639,10 @@ static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softir cp->priv = softirq; __smp_call_function_single(cpu, cp, 0); + put_online_cpus_atomic(); return 0; } + put_online_cpus_atomic(); return 1; } #else /* CONFIG_USE_GENERIC_SMP_HELPERS */