openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

x86, pci, amd-bus: 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 amd-bus code in x86 by using this latter form of callback
registration.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Srivatsa S. Bhat 2014-03-11 02:08:43 +05:30 committed by Rafael J. Wysocki
parent 9014ad2a50
commit 9f668f6661
1 changed files with 4 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
arch/x86/pci/amd_bus.c
View File

@ -380,10 +380,13 @@ static int __init pci_io_ecs_init(void)
if (early_pci_allowed())
pci_enable_pci_io_ecs();
register_cpu_notifier(&amd_cpu_notifier);
cpu_notifier_register_begin();
for_each_online_cpu(cpu)
amd_cpu_notify(&amd_cpu_notifier, (unsigned long)CPU_ONLINE,
(void *)(long)cpu);
__register_cpu_notifier(&amd_cpu_notifier);
cpu_notifier_register_done();
pci_probe |= PCI_HAS_IO_ECS;
return 0;