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authorPaul E. McKenney <paulmck@linux.ibm.com>2019-04-01 15:12:47 -0700
committerPaul E. McKenney <paulmck@linux.ibm.com>2019-05-25 14:50:48 -0700
commit385b599e8c04fa843c4d7f785478827cc512d720 (patch)
tree31ec5afef56e23943efcbf6c652059fd5e5cf73f /kernel
parent25102de65fdd246eb6801114ce6dfa3a076bb678 (diff)
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rcu: Allow rcu_read_unlock_special() to raise_softirq() if in_irq()
When running in an interrupt handler, raise_softirq() and raise_softirq_irqoff() have extremely low overhead: They simply set a bit in a per-CPU mask, which is checked upon exit from that interrupt handler. Therefore, if rcu_read_unlock_special() is invoked within an interrupt handler and RCU_SOFTIRQ is in use, this commit make use of raise_softirq_irqoff() even if there is no expedited grace period in flight and even if this is not a nohz_full CPU. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/rcu/tree_plugin.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index d15cdab6aeb4..e1005f5e8094 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -615,7 +615,7 @@ static void rcu_read_unlock_special(struct task_struct *t)
(rdp->grpmask & rnp->expmask) ||
tick_nohz_full_cpu(rdp->cpu);
// Need to defer quiescent state until everything is enabled.
- if (exp && irqs_were_disabled && use_softirq &&
+ if ((exp || in_irq()) && irqs_were_disabled && use_softirq &&
(in_irq() || !t->rcu_read_unlock_special.b.deferred_qs)) {
// Using softirq, safe to awaken, and we get
// no help from enabling irqs, unlike bh/preempt.