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Simplify stop_machine

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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>
This commit is contained in:
Rusty Russell
2008-07-28 12:16:28 -05:00
parent 5c2aed6225
commit ffdb5976c4
3 changed files with 144 additions and 198 deletions
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20
include/linux/stop_machine.h
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@ -17,13 +17,12 @@
* @data: the data ptr for the @fn()
* @cpu: if @cpu == n, run @fn() on cpu n
* if @cpu == NR_CPUS, run @fn() on any cpu
* if @cpu == ALL_CPUS, run @fn() first on the calling cpu, and then
* concurrently on all the other cpus
* if @cpu == ALL_CPUS, run @fn() on every online CPU.
*
* Description: This causes a thread to be scheduled on every other cpu,
* each of which disables interrupts, and finally interrupts are disabled
* on the current CPU. The result is that noone is holding a spinlock
* or inside any other preempt-disabled region when @fn() runs.
* Description: This causes a thread to be scheduled on every cpu,
* each of which disables interrupts. The result is that noone is
* holding a spinlock or inside any other preempt-disabled region when
* @fn() runs.
*
* This can be thought of as a very heavy write lock, equivalent to
* grabbing every spinlock in the kernel. */
@ -35,13 +34,10 @@ int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu);
* @data: the data ptr for the @fn
* @cpu: the cpu to run @fn on (or any, if @cpu == NR_CPUS.
*
* Description: This is a special version of the above, which returns the
* thread which has run @fn(): kthread_stop will return the return value
* of @fn(). Used by hotplug cpu.
* Description: This is a special version of the above, which assumes cpus
* won't come or go while it's being called. Used by hotplug cpu.
*/
struct task_struct *__stop_machine_run(int (*fn)(void *), void *data,
unsigned int cpu);
int __stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu);
#else
static inline int stop_machine_run(int (*fn)(void *), void *data,