Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756228AbaBEWTV (ORCPT ); Wed, 5 Feb 2014 17:19:21 -0500 Received: from e28smtp01.in.ibm.com ([122.248.162.1]:43725 "EHLO e28smtp01.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755307AbaBEWTR (ORCPT ); Wed, 5 Feb 2014 17:19:17 -0500 From: "Srivatsa S. Bhat" Subject: [PATCH 51/51] net/iucv/iucv.c: Fix CPU hotplug callback registration To: paulus@samba.org, oleg@redhat.com, rusty@rustcorp.com.au, peterz@infradead.org, tglx@linutronix.de, akpm@linux-foundation.org Cc: mingo@kernel.org, paulmck@linux.vnet.ibm.com, tj@kernel.org, walken@google.com, ego@linux.vnet.ibm.com, linux@arm.linux.org.uk, linux-kernel@vger.kernel.org, srivatsa.bhat@linux.vnet.ibm.com, Ursula Braun , "David S. Miller" , linux-s390@vger.kernel.org, netdev@vger.kernel.org, "Srivatsa S. Bhat" Date: Thu, 06 Feb 2014 03:43:55 +0530 Message-ID: <20140205221354.19080.25861.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20140205220251.19080.92336.stgit@srivatsabhat.in.ibm.com> References: <20140205220251.19080.92336.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14020522-4790-0000-0000-00000C92CDE1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Subsystems that want to register CPU hotplug callbacks, as well as perform initialization for the CPUs that are already online, often do it as shown below: get_online_cpus(); for_each_online_cpu(cpu) init_cpu(cpu); register_cpu_notifier(&foobar_cpu_notifier); put_online_cpus(); This is wrong, since it is prone to ABBA deadlocks involving the cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently with CPU hotplug operations). Instead, the correct and race-free way of performing the callback registration is: cpu_maps_update_begin(); for_each_online_cpu(cpu) init_cpu(cpu); /* Note the use of the double underscored version of the API */ __register_cpu_notifier(&foobar_cpu_notifier); cpu_maps_update_done(); Fix the code in net/iucv/iucv.c by using this latter form of callback registration. Also, provide helper functions to perform the common memory allocations and frees, to condense repetitive code. Cc: Ursula Braun Cc: "David S. Miller" Cc: linux-s390@vger.kernel.org Cc: netdev@vger.kernel.org Signed-off-by: Srivatsa S. Bhat --- net/iucv/iucv.c | 121 ++++++++++++++++++++++++++----------------------------- 1 file changed, 57 insertions(+), 64 deletions(-) diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c index cd5b8ec..f92348b 100644 --- a/net/iucv/iucv.c +++ b/net/iucv/iucv.c @@ -621,6 +621,42 @@ static void iucv_disable(void) put_online_cpus(); } +static void free_iucv_data(int cpu) +{ + kfree(iucv_param_irq[cpu]); + iucv_param_irq[cpu] = NULL; + kfree(iucv_param[cpu]); + iucv_param[cpu] = NULL; + kfree(iucv_irq_data[cpu]); + iucv_irq_data[cpu] = NULL; +} + +static int alloc_iucv_data(int cpu) +{ + /* Note: GFP_DMA used to get memory below 2G */ + iucv_irq_data[cpu] = kmalloc_node(sizeof(struct iucv_irq_data), + GFP_KERNEL|GFP_DMA, cpu_to_node(cpu)); + if (!iucv_irq_data[cpu]) + goto out_free; + + /* Allocate parameter blocks. */ + iucv_param[cpu] = kmalloc_node(sizeof(union iucv_param), + GFP_KERNEL|GFP_DMA, cpu_to_node(cpu)); + if (!iucv_param[cpu]) + goto out_free; + + iucv_param_irq[cpu] = kmalloc_node(sizeof(union iucv_param), + GFP_KERNEL|GFP_DMA, cpu_to_node(cpu)); + if (!iucv_param_irq[cpu]) + goto out_free; + + return 0; + +out_free: + free_iucv_data(cpu); + return -ENOMEM; +} + static int iucv_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { @@ -630,38 +666,14 @@ static int iucv_cpu_notify(struct notifier_block *self, switch (action) { case CPU_UP_PREPARE: case CPU_UP_PREPARE_FROZEN: - iucv_irq_data[cpu] = kmalloc_node(sizeof(struct iucv_irq_data), - GFP_KERNEL|GFP_DMA, cpu_to_node(cpu)); - if (!iucv_irq_data[cpu]) - return notifier_from_errno(-ENOMEM); - - iucv_param[cpu] = kmalloc_node(sizeof(union iucv_param), - GFP_KERNEL|GFP_DMA, cpu_to_node(cpu)); - if (!iucv_param[cpu]) { - kfree(iucv_irq_data[cpu]); - iucv_irq_data[cpu] = NULL; + if (alloc_iucv_data(cpu)) return notifier_from_errno(-ENOMEM); - } - iucv_param_irq[cpu] = kmalloc_node(sizeof(union iucv_param), - GFP_KERNEL|GFP_DMA, cpu_to_node(cpu)); - if (!iucv_param_irq[cpu]) { - kfree(iucv_param[cpu]); - iucv_param[cpu] = NULL; - kfree(iucv_irq_data[cpu]); - iucv_irq_data[cpu] = NULL; - return notifier_from_errno(-ENOMEM); - } break; case CPU_UP_CANCELED: case CPU_UP_CANCELED_FROZEN: case CPU_DEAD: case CPU_DEAD_FROZEN: - kfree(iucv_param_irq[cpu]); - iucv_param_irq[cpu] = NULL; - kfree(iucv_param[cpu]); - iucv_param[cpu] = NULL; - kfree(iucv_irq_data[cpu]); - iucv_irq_data[cpu] = NULL; + free_iucv_data(cpu); break; case CPU_ONLINE: case CPU_ONLINE_FROZEN: @@ -2025,33 +2037,20 @@ static int __init iucv_init(void) goto out_int; } - for_each_online_cpu(cpu) { - /* Note: GFP_DMA used to get memory below 2G */ - iucv_irq_data[cpu] = kmalloc_node(sizeof(struct iucv_irq_data), - GFP_KERNEL|GFP_DMA, cpu_to_node(cpu)); - if (!iucv_irq_data[cpu]) { - rc = -ENOMEM; - goto out_free; - } + cpu_maps_update_begin(); - /* Allocate parameter blocks. */ - iucv_param[cpu] = kmalloc_node(sizeof(union iucv_param), - GFP_KERNEL|GFP_DMA, cpu_to_node(cpu)); - if (!iucv_param[cpu]) { - rc = -ENOMEM; - goto out_free; - } - iucv_param_irq[cpu] = kmalloc_node(sizeof(union iucv_param), - GFP_KERNEL|GFP_DMA, cpu_to_node(cpu)); - if (!iucv_param_irq[cpu]) { + for_each_online_cpu(cpu) { + if (alloc_iucv_data(cpu)) { rc = -ENOMEM; goto out_free; } - } - rc = register_hotcpu_notifier(&iucv_cpu_notifier); + rc = __register_hotcpu_notifier(&iucv_cpu_notifier); if (rc) goto out_free; + + cpu_maps_update_done(); + rc = register_reboot_notifier(&iucv_reboot_notifier); if (rc) goto out_cpu; @@ -2069,16 +2068,14 @@ static int __init iucv_init(void) out_reboot: unregister_reboot_notifier(&iucv_reboot_notifier); out_cpu: - unregister_hotcpu_notifier(&iucv_cpu_notifier); + cpu_maps_update_begin(); + __unregister_hotcpu_notifier(&iucv_cpu_notifier); out_free: - for_each_possible_cpu(cpu) { - kfree(iucv_param_irq[cpu]); - iucv_param_irq[cpu] = NULL; - kfree(iucv_param[cpu]); - iucv_param[cpu] = NULL; - kfree(iucv_irq_data[cpu]); - iucv_irq_data[cpu] = NULL; - } + for_each_possible_cpu(cpu) + free_iucv_data(cpu); + + cpu_maps_update_done(); + root_device_unregister(iucv_root); out_int: unregister_external_interrupt(0x4000, iucv_external_interrupt); @@ -2105,15 +2102,11 @@ static void __exit iucv_exit(void) kfree(p); spin_unlock_irq(&iucv_queue_lock); unregister_reboot_notifier(&iucv_reboot_notifier); - unregister_hotcpu_notifier(&iucv_cpu_notifier); - for_each_possible_cpu(cpu) { - kfree(iucv_param_irq[cpu]); - iucv_param_irq[cpu] = NULL; - kfree(iucv_param[cpu]); - iucv_param[cpu] = NULL; - kfree(iucv_irq_data[cpu]); - iucv_irq_data[cpu] = NULL; - } + cpu_maps_update_begin(); + __unregister_hotcpu_notifier(&iucv_cpu_notifier); + for_each_possible_cpu(cpu) + free_iucv_data(cpu); + cpu_maps_update_done(); root_device_unregister(iucv_root); bus_unregister(&iucv_bus); unregister_external_interrupt(0x4000, iucv_external_interrupt); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/