rcu: add support for dynamic ticks and preempt rcu
The PREEMPT-RCU can get stuck if a CPU goes idle and NO_HZ is set. The idle CPU will not progress the RCU through its grace period and a synchronize_rcu my get stuck. Without this patch I have a box that will not boot when PREEMPT_RCU and NO_HZ are set. That same box boots fine with this patch. This patch comes from the -rt kernel where it has been tested for several months. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Ingo Molnar
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c0f4133b8f
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2232c2d8e0
@@ -160,5 +160,8 @@ extern void rcu_restart_cpu(int cpu);
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extern long rcu_batches_completed(void);
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extern long rcu_batches_completed_bh(void);
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#define rcu_enter_nohz() do { } while (0)
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#define rcu_exit_nohz() do { } while (0)
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#endif /* __KERNEL__ */
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#endif /* __LINUX_RCUCLASSIC_H */
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