linux-kernel - [tip:locking/core] locking/rtmutex: Get rid of RT_MUTEX_OWNER

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Date:   Fri, 2 Dec 2016 02:46:16 -0800
From:   tip-bot for Thomas Gleixner <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     torvalds@...ux-foundation.org, hpa@...or.com, tglx@...utronix.de,
        rostedt@...dmis.org, mingo@...nel.org, ddaney@...iumnetworks.com,
        mark.rutland@....com, peterz@...radead.org,
        linux-kernel@...r.kernel.org, will.deacon@....com,
        bigeasy@...utronix.de
Subject: [tip:locking/core] locking/rtmutex: Get rid of
 RT_MUTEX_OWNER_MASKALL

Commit-ID:  b5016e8203003c44264ec88fe2276ff54a51f689
Gitweb:     http://git.kernel.org/tip/b5016e8203003c44264ec88fe2276ff54a51f689
Author:     Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Wed, 30 Nov 2016 21:04:44 +0000
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 2 Dec 2016 11:13:57 +0100

locking/rtmutex: Get rid of RT_MUTEX_OWNER_MASKALL

This is a left over from the original rtmutex implementation which used
both bit0 and bit1 in the owner pointer. Commit:

  8161239a8bcc ("rtmutex: Simplify PI algorithm and make highest prio task get lock")

... removed the usage of bit1, but kept the extra mask around. This is
confusing at best.

Remove it and just use RT_MUTEX_HAS_WAITERS for the masking.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: David Daney <ddaney@...iumnetworks.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Sebastian Siewior <bigeasy@...utronix.de>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Will Deacon <will.deacon@....com>
Link: http://lkml.kernel.org/r/20161130210030.509567906@linutronix.de
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/locking/rtmutex_common.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
index e317e1c..9901346 100644
--- a/kernel/locking/rtmutex_common.h
+++ b/kernel/locking/rtmutex_common.h
@@ -71,13 +71,12 @@ task_top_pi_waiter(struct task_struct *p)
  * lock->owner state tracking:
  */
 #define RT_MUTEX_HAS_WAITERS	1UL
-#define RT_MUTEX_OWNER_MASKALL	1UL
 
 static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
 {
 	unsigned long owner = (unsigned long) READ_ONCE(lock->owner);
 
-	return (struct task_struct *) (owner & ~RT_MUTEX_OWNER_MASKALL);
+	return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);
 }
 
 /*