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author | Paul E. McKenney <paul.mckenney@linaro.org> | 2011-11-23 04:43:02 (GMT) |
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committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2011-12-11 18:32:02 (GMT) |
commit | f535a607c13c7b674e0788ca5765779aa74a01c3 (patch) | |
tree | 433a07d16ff11d9f67e7991831cebf3cadfd9939 /kernel/rcutree.c | |
parent | 84ad00cb61f1cb21f0b63bc6f7dc254399eb3830 (diff) | |
download | linux-fsl-qoriq-f535a607c13c7b674e0788ca5765779aa74a01c3.tar.xz |
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.c')
-rw-r--r-- | kernel/rcutree.c | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 7fb8b0e..13fab4a 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1086,7 +1086,6 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags) * callbacks are waiting on the grace period that just now * completed. */ - rcu_schedule_wake_gp_end(); if (*rdp->nxttail[RCU_WAIT_TAIL] == NULL) { raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ @@ -1672,7 +1671,6 @@ static void rcu_process_callbacks(struct softirq_action *unused) &__get_cpu_var(rcu_sched_data)); __rcu_process_callbacks(&rcu_bh_state, &__get_cpu_var(rcu_bh_data)); rcu_preempt_process_callbacks(); - rcu_wake_cpus_for_gp_end(); trace_rcu_utilization("End RCU core"); } |