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authorThomas Gleixner <tglx@linutronix.de>2012-04-20 13:05:45 +0000
committerThomas Gleixner <tglx@linutronix.de>2012-04-26 12:06:09 +0200
commit29d5e0476e1c4a513859e7858845ad172f560389 (patch)
treeb353eee6e4cdf57207e6eba5d80564a4e8811cc9 /kernel/smpboot.h
parent38498a67aa2cf8c80754b8d304bfacc10bc582b5 (diff)
downloadlinux-sh-29d5e0476e1c4a513859e7858845ad172f560389.tar.gz
smp: Provide generic idle thread allocation
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@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: Venkatesh Pallipadi <venki@google.com> Link: http://lkml.kernel.org/r/20120420124557.102478630@linutronix.de
Diffstat (limited to 'kernel/smpboot.h')
-rw-r--r--kernel/smpboot.h10
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/smpboot.h b/kernel/smpboot.h
index d88e77165086..7943bbbab917 100644
--- a/kernel/smpboot.h
+++ b/kernel/smpboot.h
@@ -1,6 +1,16 @@
#ifndef SMPBOOT_H
#define SMPBOOT_H
+struct task_struct;
+
int smpboot_prepare(unsigned int cpu);
+#ifdef CONFIG_GENERIC_SMP_IDLE_THREAD
+struct task_struct *idle_thread_get(unsigned int cpu);
+void idle_thread_set_boot_cpu(void);
+#else
+static inline struct task_struct *idle_thread_get(unsigned int cpu) { return NULL; }
+static inline void idle_thread_set_boot_cpu(void) { }
+#endif
+
#endif