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authorPaul E. McKenney <paul.mckenney@linaro.org>2011-11-22 20:43:02 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-12-11 10:32:02 -0800
commitf535a607c13c7b674e0788ca5765779aa74a01c3 (patch)
tree433a07d16ff11d9f67e7991831cebf3cadfd9939 /kernel/rcutree.h
parent84ad00cb61f1cb21f0b63bc6f7dc254399eb3830 (diff)
downloadop-kernel-dev-f535a607c13c7b674e0788ca5765779aa74a01c3.zip
op-kernel-dev-f535a607c13c7b674e0788ca5765779aa74a01c3.tar.gz
rcu: Eliminate RCU_FAST_NO_HZ grace-period hang
With the new implementation of RCU_FAST_NO_HZ, it was possible to hang RCU grace periods as follows: o CPU 0 attempts to go idle, cycles several times through the rcu_prepare_for_idle() loop, then goes dyntick-idle when RCU needs nothing more from it, while still having at least on RCU callback pending. o CPU 1 goes idle with no callbacks. Both CPUs can then stay in dyntick-idle mode indefinitely, preventing the RCU grace period from ever completing, possibly hanging the system. This commit therefore prevents CPUs that have RCU callbacks from entering dyntick-idle mode. This approach also eliminates the need for the end-of-grace-period IPIs used previously. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree.h')
-rw-r--r--kernel/rcutree.h3
1 files changed, 0 insertions, 3 deletions
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index ea32405..70d8a55 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -88,7 +88,6 @@ struct rcu_dynticks {
/* Process level is worth LLONG_MAX/2. */
int dynticks_nmi_nesting; /* Track NMI nesting level. */
atomic_t dynticks; /* Even value for idle, else odd. */
- int wake_gp_end; /* A GP ended, need to wake up CPUs. */
};
/* RCU's kthread states for tracing. */
@@ -469,7 +468,5 @@ static void rcu_yield(void (*f)(unsigned long), unsigned long arg);
static void rcu_cpu_kthread_setrt(int cpu, int to_rt);
static void __cpuinit rcu_prepare_kthreads(int cpu);
static void rcu_prepare_for_idle(int cpu);
-static void rcu_wake_cpus_for_gp_end(void);
-static void rcu_schedule_wake_gp_end(void);
#endif /* #ifndef RCU_TREE_NONCORE */
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