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| author | Paul E. McKenney <paulmck@linux.ibm.com> | 2019-04-17 00:15:24 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.ibm.com> | 2019-08-13 23:35:49 +0200 |
| commit | ca5c8258081178c60b27e3532d9ea95b6eaa7040 (patch) | |
| tree | 485d5a3e770c0fbb1611313696d0ff264c186f47 /kernel/rcu | |
| parent | rcu/nocb: Check for deferred nocb wakeups before nohz_full early exit (diff) | |
| download | linux-ca5c8258081178c60b27e3532d9ea95b6eaa7040.tar.xz linux-ca5c8258081178c60b27e3532d9ea95b6eaa7040.zip | |
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')
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 10 |
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; } |