linux-kernel - [patch V5 47/72] locking/ww_mutex: Abstract mutex accessors

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Message-ID: <20210815211304.622477030@linutronix.de>
Date:   Sun, 15 Aug 2021 23:28:49 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Will Deacon <will@...nel.org>,
        Waiman Long <longman@...hat.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Davidlohr Bueso <dave@...olabs.net>,
        Mike Galbraith <efault@....de>
Subject: [patch V5 47/72] locking/ww_mutex: Abstract mutex accessors

From: Peter Zijlstra <peterz@...radead.org>

Move the mutex related access from various ww_mutex functions into helper
functions so they can be substituted for rtmutex based ww_mutex later.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

---
 kernel/locking/ww_mutex.h |   16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)
---
--- a/kernel/locking/ww_mutex.h
+++ b/kernel/locking/ww_mutex.h
@@ -53,6 +53,18 @@ static inline void
 	__mutex_add_waiter(lock, waiter, p);
 }
 
+static inline struct task_struct *
+__ww_mutex_owner(struct mutex *lock)
+{
+	return __mutex_owner(lock);
+}
+
+static inline bool
+__ww_mutex_has_waiters(struct mutex *lock)
+{
+	return atomic_long_read(&lock->owner) & MUTEX_FLAG_WAITERS;
+}
+
 /*
  * Wait-Die:
  *   The newer transactions are killed when:
@@ -157,7 +169,7 @@ static bool __ww_mutex_wound(struct mute
 			     struct ww_acquire_ctx *ww_ctx,
 			     struct ww_acquire_ctx *hold_ctx)
 {
-	struct task_struct *owner = __mutex_owner(lock);
+	struct task_struct *owner = __ww_mutex_owner(lock);
 
 	lockdep_assert_held(&lock->wait_lock);
 
@@ -253,7 +265,7 @@ ww_mutex_set_context_fastpath(struct ww_
 	 * __ww_mutex_add_waiter() and makes sure we either observe ww->ctx
 	 * and/or !empty list.
 	 */
-	if (likely(!(atomic_long_read(&lock->base.owner) & MUTEX_FLAG_WAITERS)))
+	if (likely(!__ww_mutex_has_waiters(&lock->base)))
 		return;
 
 	/*