aa95387774
The CPU hotplug locking was quite messy, with a recursive lock to handle the fact that both the actual up/down sequence wanted to protect itself from being re-entered, but the callbacks that it called also tended to want to protect themselves from CPU events. This splits the lock into two (one to serialize the whole hotplug sequence, the other to protect against the CPU present bitmaps changing). The latter still allows recursive usage because some subsystems (ondemand policy for cpufreq at least) had already gotten too used to the lax locking, but the locking mistakes are hopefully now less fundamental, and we now warn about recursive lock usage when we see it, in the hope that it can be fixed. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
93 lines
2.6 KiB
C
93 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 *cpu, int num);
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extern struct sys_device *get_cpu_sysdev(unsigned cpu);
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#ifdef CONFIG_HOTPLUG_CPU
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extern void unregister_cpu(struct cpu *cpu);
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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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#ifdef CONFIG_HOTPLUG_CPU
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extern void unregister_cpu_notifier(struct notifier_block *nb);
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#else
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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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#endif
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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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#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 void lock_cpu_hotplug(void);
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extern void unlock_cpu_hotplug(void);
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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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#define register_hotcpu_notifier(nb) register_cpu_notifier(nb)
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#define unregister_hotcpu_notifier(nb) unregister_cpu_notifier(nb)
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int cpu_down(unsigned 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) do { } while (0)
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#define register_hotcpu_notifier(nb) do { } while (0)
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#define unregister_hotcpu_notifier(nb) do { } while (0)
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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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