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rcu/nocb: Set SEGCBLIST_SOFTIRQ_ONLY at the very last stage of de-offloading 

This commit sets SEGCBLIST_SOFTIRQ_ONLY once toggling is otherwise fully
complete, allowing further RCU callback manipulation to be carried out
locklessly and locally.

Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Frederic Weisbecker 2020-11-13 13:13:25 +01:00 committed by Paul E. McKenney
parent 314202f84d
commit b9ced9e1ab
1 changed files with 8 additions and 1 deletions
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9
kernel/rcu/tree_plugin.h
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@ -2352,7 +2352,14 @@ static int __rcu_nocb_rdp_deoffload(struct rcu_data *rdp)
*/
rcu_nocb_lock_irqsave(rdp, flags);
rcu_nocb_flush_bypass(rdp, NULL, jiffies);
rcu_nocb_unlock_irqrestore(rdp, flags);
rcu_segcblist_set_flags(cblist, SEGCBLIST_SOFTIRQ_ONLY);
/*
* With SEGCBLIST_SOFTIRQ_ONLY, we can't use
* rcu_nocb_unlock_irqrestore() anymore. Theoretically we
* could set SEGCBLIST_SOFTIRQ_ONLY with cb unlocked and IRQs
* disabled now, but let's be paranoid.
*/
raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
return ret;
}