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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
	Waiman Long <longman@redhat.com>,
	Boqun Feng <boqun.feng@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH] locking: Remove rt_rwlock_is_contended()
Date: Tue, 7 Sep 2021 12:34:58 +0200	[thread overview]
Message-ID: <20210907103458.l2iyvjps5bjwnzng@linutronix.de> (raw)
In-Reply-To: <20210907100944.7qu3frjuuty3oi3d@linutronix.de>

rt_rwlock_is_contended() has not users. It makes no sense to use it as
rwlock_is_contended() because it is a sleeping lock on RT and preemption
is possible. It reports always != 0 if used by a writer and even if
there is a waiter then the lock might not be handed over if the
current owner has the highest priority.

Remove rt_rwlock_is_contended().

Reported-by: kernel test robot <lkp@intel.com>
Fixes: 8282947f67345 ("locking/rwlock: Provide RT variant")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 kernel/locking/spinlock_rt.c |    6 ------
 1 file changed, 6 deletions(-)

--- a/kernel/locking/spinlock_rt.c
+++ b/kernel/locking/spinlock_rt.c
@@ -246,12 +246,6 @@ void __sched rt_write_unlock(rwlock_t *r
 }
 EXPORT_SYMBOL(rt_write_unlock);
 
-int __sched rt_rwlock_is_contended(rwlock_t *rwlock)
-{
-	return rw_base_is_contended(&rwlock->rwbase);
-}
-EXPORT_SYMBOL(rt_rwlock_is_contended);
-
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 void __rt_rwlock_init(rwlock_t *rwlock, const char *name,
 		      struct lock_class_key *key)

  reply	other threads:[~2021-09-07 10:35 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-06 14:30 [PATCH 0/2] locking: Provide {rwlock|spin}_is_contended on PREEMPT_RT Sebastian Andrzej Siewior
2021-09-06 14:30 ` [PATCH 1/2] locking: Wire up rwlock_is_contended() " Sebastian Andrzej Siewior
2021-09-06 14:30 ` [PATCH 2/2] locking: Provide spin_is_contended() " Sebastian Andrzej Siewior
2021-09-07 10:09 ` [PATCH 0/2] locking: Provide {rwlock|spin}_is_contended " Sebastian Andrzej Siewior
2021-09-07 10:34   ` Sebastian Andrzej Siewior [this message]
2021-09-10 16:16     ` [PATCH] locking: Remove rt_rwlock_is_contended() Peter Zijlstra
2021-09-10 16:37       ` Sebastian Andrzej Siewior
2021-09-13 11:20         ` Peter Zijlstra

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