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From:   "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To:     linux-kernel@vger.kernel.org
Cc:     mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com,
        akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
        josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
        rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
        fweisbec@gmail.com, oleg@redhat.com, joel.opensrc@gmail.com,
        Boqun Feng <boqun.feng@gmail.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 22/22] rcu: Use the proper lockdep annotation in dump_blkd_tasks()
Date:   Sun, 22 Apr 2018 19:32:27 -0700
In-Reply-To: <20180423023150.GA21533@linux.vnet.ibm.com>
References: <20180423023150.GA21533@linux.vnet.ibm.com>
Message-Id: <1524450747-22778-22-git-send-email-paulmck@linux.vnet.ibm.com>
Sender: linux-kernel-owner@vger.kernel.org
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From: Boqun Feng <boqun.feng@gmail.com>

Sparse reported this:

| kernel/rcu/tree_plugin.h:814:9: warning: incorrect type in argument 1 (different modifiers)
| kernel/rcu/tree_plugin.h:814:9:    expected struct lockdep_map const *lock
| kernel/rcu/tree_plugin.h:814:9:    got struct lockdep_map [noderef] *<noident>

This is caused by using vanilla lockdep annotations on rcu_node::lock,
and that requires accessing ->lock of rcu_node directly. However we need
to keep rcu_node::lock __private to avoid breaking its extra ordering
guarantee. And we have a dedicated lockdep annotation for
rcu_node::lock, so use it.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcu/tree_plugin.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 8014a09a5c9b..52bd92acbe6b 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -855,7 +855,7 @@ static void dump_blkd_tasks(struct rcu_node *rnp, int ncheck)
 	int i;
 	struct list_head *lhp;
 
-	lockdep_assert_held(&rnp->lock);
+	raw_lockdep_assert_held_rcu_node(rnp);
 	pr_info("%s: grp: %d-%d level: %d ->qamask %#lx ->gp_tasks %p ->boost_tasks %p ->exp_tasks %p &->blkd_tasks: %p offset: %u\n", __func__, rnp->grplo, rnp->grphi, rnp->level, rnp->qsmask, rnp->gp_tasks, rnp->boost_tasks, rnp->exp_tasks, &rnp->blkd_tasks, (unsigned int)offsetof(typeof(*rnp), blkd_tasks));
 	pr_cont("\t->blkd_tasks");
 	i = 0;
-- 
2.5.2