ffdb5976c4
stop_machine creates a kthread which creates kernel threads. We can create those threads directly and simplify things a little. Some care must be taken with CPU hotunplug, which has special needs, but that code seems more robust than it was in the past. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
54 lines
1.7 KiB
C
54 lines
1.7 KiB
C
#ifndef _LINUX_STOP_MACHINE
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#define _LINUX_STOP_MACHINE
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/* "Bogolock": stop the entire machine, disable interrupts. This is a
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very heavy lock, which is equivalent to grabbing every spinlock
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(and more). So the "read" side to such a lock is anything which
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diables preeempt. */
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#include <linux/cpu.h>
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#include <asm/system.h>
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#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
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#define ALL_CPUS ~0U
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/**
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* stop_machine_run: freeze the machine on all CPUs and run this function
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* @fn: the function to run
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* @data: the data ptr for the @fn()
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* @cpu: if @cpu == n, run @fn() on cpu n
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* if @cpu == NR_CPUS, run @fn() on any cpu
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* if @cpu == ALL_CPUS, run @fn() on every online CPU.
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*
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* Description: This causes a thread to be scheduled on every cpu,
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* each of which disables interrupts. The result is that noone is
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* holding a spinlock or inside any other preempt-disabled region when
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* @fn() runs.
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*
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* This can be thought of as a very heavy write lock, equivalent to
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* grabbing every spinlock in the kernel. */
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int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu);
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/**
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* __stop_machine_run: freeze the machine on all CPUs and run this function
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* @fn: the function to run
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* @data: the data ptr for the @fn
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* @cpu: the cpu to run @fn on (or any, if @cpu == NR_CPUS.
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*
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* Description: This is a special version of the above, which assumes cpus
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* won't come or go while it's being called. Used by hotplug cpu.
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*/
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int __stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu);
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#else
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static inline int stop_machine_run(int (*fn)(void *), void *data,
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unsigned int cpu)
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{
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int ret;
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local_irq_disable();
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ret = fn(data);
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local_irq_enable();
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return ret;
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}
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#endif /* CONFIG_SMP */
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#endif /* _LINUX_STOP_MACHINE */
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