90d45d17f3
When calling target drivers to set frequency, we take cpucontrol lock. When we modified the code to accomodate CPU hotplug, there was an attempt to take a double lock of cpucontrol leading to a deadlock. Since the current thread context is already holding the cpucontrol lock, we dont need to make another attempt to acquire it. Now we leave a trace in current->flags indicating current thread already is under cpucontrol lock held, so we dont attempt to do this another time. Thanks to Andrew Morton for the beating:-) From: Brice Goglin <Brice.Goglin@ens-lyon.org> Build fix (akpm: this patch is still unpleasant. Ashok continues to look for a cleaner solution, doesn't he? ;)) Signed-off-by: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Brice Goglin <Brice.Goglin@ens-lyon.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
90 lines
2.6 KiB
C
90 lines
2.6 KiB
C
/*
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* include/linux/cpu.h - generic cpu definition
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*
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* This is mainly for topological representation. We define the
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* basic 'struct cpu' here, which can be embedded in per-arch
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* definitions of processors.
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*
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* Basic handling of the devices is done in drivers/base/cpu.c
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* and system devices are handled in drivers/base/sys.c.
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*
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* CPUs are exported via sysfs in the class/cpu/devices/
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* directory.
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*
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* Per-cpu interfaces can be implemented using a struct device_interface.
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* See the following for how to do this:
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* - drivers/base/intf.c
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* - Documentation/driver-model/interface.txt
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*/
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#ifndef _LINUX_CPU_H_
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#define _LINUX_CPU_H_
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#include <linux/sysdev.h>
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#include <linux/node.h>
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#include <linux/compiler.h>
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#include <linux/cpumask.h>
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#include <asm/semaphore.h>
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struct cpu {
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int node_id; /* The node which contains the CPU */
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int no_control; /* Should the sysfs control file be created? */
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struct sys_device sysdev;
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};
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extern int register_cpu(struct cpu *, int, struct node *);
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extern struct sys_device *get_cpu_sysdev(int cpu);
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#ifdef CONFIG_HOTPLUG_CPU
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extern void unregister_cpu(struct cpu *, struct node *);
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#endif
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struct notifier_block;
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#ifdef CONFIG_SMP
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/* Need to know about CPUs going up/down? */
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extern int register_cpu_notifier(struct notifier_block *nb);
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extern void unregister_cpu_notifier(struct notifier_block *nb);
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extern int current_in_cpu_hotplug(void);
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int cpu_up(unsigned int cpu);
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#else
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static inline int register_cpu_notifier(struct notifier_block *nb)
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{
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return 0;
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}
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static inline void unregister_cpu_notifier(struct notifier_block *nb)
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{
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}
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static inline int current_in_cpu_hotplug(void)
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{
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return 0;
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}
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#endif /* CONFIG_SMP */
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extern struct sysdev_class cpu_sysdev_class;
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#ifdef CONFIG_HOTPLUG_CPU
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/* Stop CPUs going up and down. */
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extern struct semaphore cpucontrol;
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#define lock_cpu_hotplug() down(&cpucontrol)
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#define unlock_cpu_hotplug() up(&cpucontrol)
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#define lock_cpu_hotplug_interruptible() down_interruptible(&cpucontrol)
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#define hotcpu_notifier(fn, pri) { \
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static struct notifier_block fn##_nb = \
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{ .notifier_call = fn, .priority = pri }; \
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register_cpu_notifier(&fn##_nb); \
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}
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int cpu_down(unsigned int cpu);
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extern int __attribute__((weak)) smp_prepare_cpu(int cpu);
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#define cpu_is_offline(cpu) unlikely(!cpu_online(cpu))
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#else
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#define lock_cpu_hotplug() do { } while (0)
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#define unlock_cpu_hotplug() do { } while (0)
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#define lock_cpu_hotplug_interruptible() 0
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#define hotcpu_notifier(fn, pri)
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/* CPUs don't go offline once they're online w/o CONFIG_HOTPLUG_CPU */
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static inline int cpu_is_offline(int cpu) { return 0; }
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#endif
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#endif /* _LINUX_CPU_H_ */
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