From a0e247a8059223593f9c5c3d5c1fd50eedf415c0 Mon Sep 17 00:00:00 2001 From: "Srivatsa S. Bhat" Date: Tue, 11 Mar 2014 02:12:57 +0530 Subject: net/iucv/iucv.c: Fix CPU hotplug callback registration 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_notifier_register_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_notifier_register_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: Ingo Molnar Acked-by: David S. Miller Signed-off-by: Srivatsa S. Bhat Signed-off-by: Rafael J. Wysocki --- net/iucv/iucv.c | 121 ++++++++++++++++++++++++++------------------------------ 1 file changed, 57 insertions(+), 64 deletions(-) (limited to 'net') diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c index cd5b8ec9be04..79a0ce95799f 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_notifier_register_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_notifier_register_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_notifier_register_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_notifier_register_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_notifier_register_begin(); + __unregister_hotcpu_notifier(&iucv_cpu_notifier); + for_each_possible_cpu(cpu) + free_iucv_data(cpu); + cpu_notifier_register_done(); root_device_unregister(iucv_root); bus_unregister(&iucv_bus); unregister_external_interrupt(0x4000, iucv_external_interrupt); -- cgit v1.2.3