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authorTejun Heo <tj@kernel.org>2011-06-23 11:19:28 -0700
committerH. Peter Anvin <hpa@linux.intel.com>2011-06-27 15:17:08 -0700
commitf740e6cd0cb5e7468e46831aeb4d9c30e03d5ebc (patch)
tree83d81928de5d3ebc3b325f633dddd77a0e6ad662 /include/linux/stop_machine.h
parentfd7355ba1e936487f5aae6fc058c6cb300e44a64 (diff)
downloadlinux-linaro-stable-f740e6cd0cb5e7468e46831aeb4d9c30e03d5ebc.tar.gz
stop_machine: implement stop_machine_from_inactive_cpu()
Currently, mtrr wants stop_machine functionality while a CPU is being brought up. As stop_machine() requires the calling CPU to be active, mtrr implements its own stop_machine using stop_one_cpu() on each online CPU. This doesn't only unnecessarily duplicate complex logic but also introduces a possibility of deadlock when it races against the generic stop_machine(). This patch implements stop_machine_from_inactive_cpu() to serve such use cases. Its functionality is basically the same as stop_machine(); however, it should be called from a CPU which isn't active and doesn't depend on working scheduling on the calling CPU. This is achieved by using busy loops for synchronization and open-coding stop_cpus queuing and waiting with direct invocation of fn() for local CPU inbetween. Signed-off-by: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20110623182056.982526827@sbsiddha-MOBL3.sc.intel.com Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'include/linux/stop_machine.h')
-rw-r--r--include/linux/stop_machine.h14
1 files changed, 12 insertions, 2 deletions
diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h
index 14d3524d1274..e0f2da25d751 100644
--- a/include/linux/stop_machine.h
+++ b/include/linux/stop_machine.h
@@ -126,15 +126,19 @@ int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
*/
int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
+int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
+ const struct cpumask *cpus);
+
#else /* CONFIG_STOP_MACHINE && CONFIG_SMP */
static inline int __stop_machine(int (*fn)(void *), void *data,
const struct cpumask *cpus)
{
+ unsigned long flags;
int ret;
- local_irq_disable();
+ local_irq_save(flags);
ret = fn(data);
- local_irq_enable();
+ local_irq_restore(flags);
return ret;
}
@@ -144,5 +148,11 @@ static inline int stop_machine(int (*fn)(void *), void *data,
return __stop_machine(fn, data, cpus);
}
+static inline int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
+ const struct cpumask *cpus)
+{
+ return __stop_machine(fn, data, cpus);
+}
+
#endif /* CONFIG_STOP_MACHINE && CONFIG_SMP */
#endif /* _LINUX_STOP_MACHINE */