Commit 13817dd5 authored Feb 04, 2020 by Paul E. McKenney

rcu: Tighten rcu_lockdep_assert_cblist_protected() check

The ->nocb_lock lockdep assertion is currently guarded by cpu_online(),
which is incorrect for no-CBs CPUs, whose callback lists must be
protected by ->nocb_lock regardless of whether or not the corresponding
CPU is online. This situation could result in failure to detect bugs
resulting from failing to hold ->nocb_lock for offline CPUs.

This commit therefore removes the cpu_online() guard.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

parent faa059c3

kernel/rcu/tree_plugin.h

+1 −2

Original line number	Diff line number	Diff line
		@@ -1579,8 +1579,7 @@ static void rcu_nocb_unlock_irqrestore(struct rcu_data *rdp,
		static void rcu_lockdep_assert_cblist_protected(struct rcu_data *rdp)
		{
		lockdep_assert_irqs_disabled();
		if (rcu_segcblist_is_offloaded(&rdp->cblist) &&
		cpu_online(rdp->cpu))
		if (rcu_segcblist_is_offloaded(&rdp->cblist))
		lockdep_assert_held(&rdp->nocb_lock);
		}

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