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authorPaul E. McKenney <paulmck@linux.ibm.com>2019-04-16 15:15:24 -0700
committerPaul E. McKenney <paulmck@linux.ibm.com>2019-08-13 14:35:49 -0700
commitca5c8258081178c60b27e3532d9ea95b6eaa7040 (patch)
tree485d5a3e770c0fbb1611313696d0ff264c186f47 /kernel/rcu/tree_plugin.h
parent85f69b32126dcf798f2c8d69a7957ba990bc2e02 (diff)
downloadlinux-ca5c8258081178c60b27e3532d9ea95b6eaa7040.tar.bz2
rcu/nocb: Remove deferred wakeup checks for extended quiescent states
The idea behind the checks for extended quiescent states at the end of __call_rcu_nocb() is to handle cases where call_rcu() is invoked directly from within an extended quiescent state, for example, from the idle loop. However, this will result in a timer-mediated deferred wakeup, which will cause the needed wakeup to happen within a jiffy or thereabouts. There should be no forward-progress concerns, and if there are, the proper response is to exit the extended quiescent state while executing the endless blast of call_rcu() invocations, for example, using RCU_NONIDLE(). Given the more realistic case of an isolated call_rcu() invocation, there should be no problem. This commit therefore removes the checks for invoking call_rcu() within an extended quiescent state for on no-CBs CPUs. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Diffstat (limited to 'kernel/rcu/tree_plugin.h')
-rw-r--r--kernel/rcu/tree_plugin.h10
1 files changed, 0 insertions, 10 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index fc6133eed50a..9936a66b80bb 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1709,16 +1709,6 @@ static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp,
-atomic_long_read(&rdp->nocb_q_count_lazy),
-rcu_get_n_cbs_nocb_cpu(rdp));
- /*
- * If called from an extended quiescent state with interrupts
- * disabled, invoke the RCU core in order to allow the idle-entry
- * deferred-wakeup check to function.
- */
- if (irqs_disabled_flags(flags) &&
- !rcu_is_watching() &&
- cpu_online(smp_processor_id()))
- invoke_rcu_core();
-
return true;
}