45 lines
1.7 KiB
Diff
45 lines
1.7 KiB
Diff
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From 36fe38776bb6cec8f0ad04b9cca942b2f07f60b5 Mon Sep 17 00:00:00 2001
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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
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Date: Wed, 6 Jun 2018 15:31:31 +0200
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Subject: [PATCH 349/365] rcu: Suppress lockdep false-positive ->boost_mtx
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complaints
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[ Upstream commit 02a7c234e54052101164368ff981bd72f7acdd65 ]
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RCU priority boosting uses rt_mutex_init_proxy_locked() to initialize an
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rt_mutex structure in locked state held by some other task. When that
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other task releases it, lockdep complains (quite accurately, but a bit
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uselessly) that the other task never acquired it. This complaint can
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suppress other, more helpful, lockdep complaints, and in any case it is
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a false positive.
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This commit therefore switches from rt_mutex_unlock() to
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rt_mutex_futex_unlock(), thereby avoiding the lockdep annotations.
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Of course, if lockdep ever learns about rt_mutex_init_proxy_locked(),
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addtional adjustments will be required.
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Suggested-by: Peter Zijlstra <peterz@infradead.org>
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Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Signed-off-by: Julia Cartwright <julia@ni.com>
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---
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kernel/rcu/tree_plugin.h | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
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index 3d18d08e8382..510de72ad8a3 100644
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--- a/kernel/rcu/tree_plugin.h
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+++ b/kernel/rcu/tree_plugin.h
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@@ -486,7 +486,7 @@ void rcu_read_unlock_special(struct task_struct *t)
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/* Unboost if we were boosted. */
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if (IS_ENABLED(CONFIG_RCU_BOOST) && drop_boost_mutex)
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- rt_mutex_unlock(&rnp->boost_mtx);
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+ rt_mutex_futex_unlock(&rnp->boost_mtx);
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/*
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* If this was the last task on the expedited lists,
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--
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2.28.0
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