Messages in this thread | | | Subject | Re: [patch 3/9] cpu: deliver CPU_UP_CANCELED only to NOTIFY_OKed callbacks with CPU_UP_PREPARE | From | Rusty Russell <> | Date | Mon, 23 Jul 2007 09:48:10 +1000 |
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On Mon, 2007-07-23 at 00:33 +0900, Akinobu Mita wrote: > plain text document attachment (cpuhotplug-nr-calls.patch) > From: Akinobu Mita <akinobu.mita@gmail.com> > > The functions in a CPU notifier chain is called with CPU_UP_PREPARE event > before making the CPU online. If one of the callback returns NOTIFY_BAD, > it stops to deliver CPU_UP_PREPARE event, and CPU online operation is canceled. > Then CPU_UP_CANCELED event is delivered to the functions in a CPU notifier > chain again. > > This CPU_UP_CANCELED event is delivered to the functions which have been > called with CPU_UP_PREPARE, not delivered to the functions which haven't > been called with CPU_UP_PREPARE. > > The problem that makes existing cpu hotplug error handlings complex is > that the CPU_UP_CANCELED event is delivered to the function that has > returned NOTIFY_BAD, too. > > Usually we don't expect to call destructor function against the > object that has failed to initialize. It is like: > > err = register_something(); > if (err) { > unregister_something(); > return err; > } > > So it is natural to deliver CPU_UP_CANCELED event only to the functions > that have returned NOTIFY_OK with CPU_UP_PREPARE event and not to call > the function that have returned NOTIFY_BAD. This is what this patch is doing. > > Otherwise, every cpu hotplug notifiler has to track whether > notifiler event is failed or not for each cpu. > (drivers/base/topology.c is doing this with topology_dev_map) > > Similary this patch makes same thing with CPU_DOWN_PREPARE and > CPU_DOWN_FAILED evnets. > > Cc: Rusty Russell <rusty@rustcorp.com.au> > Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
This makes a great deal of sense; I consider it a bugfix.
Thanks! Rusty.
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