linux/net/iucv
Srivatsa S. Bhat a0e247a805 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 <ursula.braun@de.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-03-20 13:43:48 +01:00
..
af_iucv.c net: rework recvmsg handler msg_name and msg_namelen logic 2013-11-20 21:52:30 -05:00
iucv.c net/iucv/iucv.c: Fix CPU hotplug callback registration 2014-03-20 13:43:48 +01:00
Kconfig iucv: kernel option for z/VM IUCV and HiperSockets 2011-08-13 01:10:16 -07:00
Makefile