The following commit has been merged into the core/rcu branch of tip: Commit-ID: b9ced9e1ab51ed6057ac8198fd1eeb404a32a867 Gitweb: https://git.kernel.org/tip/b9ced9e1ab51ed6057ac8198fd1eeb404a32a867 Author: Frederic Weisbecker <frederic@xxxxxxxxxx> AuthorDate: Fri, 13 Nov 2020 13:13:25 +01:00 Committer: Paul E. McKenney <paulmck@xxxxxxxxxx> CommitterDate: Wed, 06 Jan 2021 16:24:59 -08:00 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@xxxxxxxxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx> Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> Cc: Neeraj Upadhyay <neeraju@xxxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Inspired-by: Paul E. McKenney <paulmck@xxxxxxxxxx> Tested-by: Boqun Feng <boqun.feng@xxxxxxxxx> Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> --- kernel/rcu/tree_plugin.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 35dc9b3..8641b72 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -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; }
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