From: Akinobu Mita Date: Thu, 18 Oct 2007 10:05:12 +0000 (-0700) Subject: cpu hotplug: cpu: deliver CPU_UP_CANCELED only to NOTIFY_OKed callbacks with CPU_UP_P... X-Git-Tag: v2.6.24-rc1~409 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a0d8cdb652d35af9319a9e0fb7134de2a276c636;p=pandora-kernel.git cpu hotplug: cpu: deliver CPU_UP_CANCELED only to NOTIFY_OKed callbacks with CPU_UP_PREPARE 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. Acked-by: Rusty Russell Signed-off-by: Akinobu Mita Cc: Gautham R Shenoy Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed