On 04/20/12 06:05, Thomas Gleixner wrote:
> 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: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Matt Turner <mattst88@xxxxxxxxx>
> Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
> Cc: Mike Frysinger <vapier@xxxxxxxxxx>
> Cc: Jesper Nilsson <jesper.nilsson@xxxxxxxx>
> Cc: Richard Kuo <rkuo@xxxxxxxxxxxxxx>
> Cc: Tony Luck <tony.luck@xxxxxxxxx>
> Cc: Hirokazu Takata <takata@xxxxxxxxxxxxxx>
> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
> Cc: David Howells <dhowells@xxxxxxxxxx>
> Cc: "James E.J. Bottomley" <jejb@xxxxxxxxxxxxxxxx>
> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
> Cc: Paul Mundt <lethal@xxxxxxxxxxxx>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: Chris Metcalf <cmetcalf@xxxxxxxxxx>
> Cc: Richard Weinberger <richard@xxxxxx>
> Cc: x86@xxxxxxxxxx
> ---
> arch/Kconfig | 3 +
> kernel/cpu.c | 2 -
> kernel/sched/core.c | 2 +
> kernel/smpboot.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> kernel/smpboot.h | 10 ++++++
> 5 files changed, 99 insertions(+), 1 deletion(-)
>
> Index: linux-2.6/arch/Kconfig
> ===================================================================
> --- linux-2.6.orig/arch/Kconfig
> +++ linux-2.6/arch/Kconfig
> @@ -145,6 +145,9 @@ config HAVE_DMA_ATTRS
> config USE_GENERIC_SMP_HELPERS
> bool
>
> +config GENERIC_SMP_IDLE_THREAD
> + bool
^^^^^ This _appears_ to be spaces instead of a tab. Hopefully not a false alarm, I know
my mail servers randomly change tabs to spaces, just to mess with me, but I double
checked at the lkml archive.
> +
> config HAVE_REGS_AND_STACK_ACCESS_API
> bool
> help
< snip >
- Frank
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