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    smp: Provide generic idle thread allocation · 29d5e047
    Thomas Gleixner 提交于
    All SMP architectures have magic to fork the idle task and to store it
    for reusage when cpu hotplug is enabled. Provide a generic
    infrastructure for it.
    
    Create/reinit the idle thread for the cpu which is brought up in the
    generic code and hand the thread pointer to the architecture code via
    __cpu_up().
    
    Note, that fork_idle() is called via a workqueue, because this
    guarantees that the idle thread does not get a reference to a user
    space VM. This can happen when the boot process did not bring up all
    possible cpus and a later cpu_up() is initiated via the sysfs
    interface. In that case fork_idle() would be called in the context of
    the user space task and take a reference on the user space VM.
    Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Rusty Russell <rusty@rustcorp.com.au>
    Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
    Cc: Matt Turner <mattst88@gmail.com>
    Cc: Russell King <linux@arm.linux.org.uk>
    Cc: Mike Frysinger <vapier@gentoo.org>
    Cc: Jesper Nilsson <jesper.nilsson@axis.com>
    Cc: Richard Kuo <rkuo@codeaurora.org>
    Cc: Tony Luck <tony.luck@intel.com>
    Cc: Hirokazu Takata <takata@linux-m32r.org>
    Cc: Ralf Baechle <ralf@linux-mips.org>
    Cc: David Howells <dhowells@redhat.com>
    Cc: James E.J. Bottomley <jejb@parisc-linux.org>
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
    Cc: Paul Mundt <lethal@linux-sh.org>
    Cc: David S. Miller <davem@davemloft.net>
    Cc: Chris Metcalf <cmetcalf@tilera.com>
    Cc: Richard Weinberger <richard@nod.at>
    Cc: x86@kernel.org
    Acked-by: NVenkatesh Pallipadi <venki@google.com>
    Link: http://lkml.kernel.org/r/20120420124557.102478630@linutronix.de
    29d5e047
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