[tip/core/rcu,26/30] rcu: Tighten rcu_lockdep_assert_cblist_protected() check
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Message ID 20200214235607.13749-26-paulmck@kernel.org
State In Next
Commit a66534f90e54c5914f2b73351e628ac4a7da24bf
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Series
  • Miscellaneous fixes for v5.7
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Commit Message

Paul E. McKenney Feb. 14, 2020, 11:56 p.m. UTC
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(-)

Patch
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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);
 }