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Subject[PATCH tip/core/rcu 26/30] rcu: Tighten rcu_lockdep_assert_cblist_protected() check
Date
From: "Paul E. McKenney" <paulmck@kernel.org>

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>
---
kernel/rcu/tree_plugin.h | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 3846519..70b3c0f 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -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);
}

--
2.9.5
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