linux-kernel - [PATCH] x86: eliminate TICKET

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Date:	Fri, 03 Feb 2012 15:06:26 +0000
From:	"Jan Beulich" <JBeulich@...e.com>
To:	<mingo@...e.hu>, <tglx@...utronix.de>, <hpa@...or.com>
Cc:	"Jeremy Fitzhardinge" <jeremy@...p.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH] x86: eliminate TICKET_MASK

The definition of it being questionable already (unnecessarily
including a cast), and it being used in a single place that can be
written shorter without it, remove this #define.

Along the same lines, simplify __ticket_spin_is_locked()'s main
expression, which was the more convoluted way because of needs that
went away with the recent type changes by Jeremy.

This is pure cleanup, no functional change intended.

Signed-off-by: Jan Beulich <jbeulich@...e.com>
Cc: Jeremy Fitzhardinge <jeremy@...p.org>

---
 arch/x86/include/asm/spinlock.h       |    4 ++--
 arch/x86/include/asm/spinlock_types.h |    1 -
 2 files changed, 2 insertions(+), 3 deletions(-)

--- 3.3-rc2/arch/x86/include/asm/spinlock.h
+++ 3.3-rc2-x86-ticket-mask/arch/x86/include/asm/spinlock.h
@@ -88,14 +88,14 @@ static inline int __ticket_spin_is_locke
 {
 	struct __raw_tickets tmp = ACCESS_ONCE(lock->tickets);
 
-	return !!(tmp.tail ^ tmp.head);
+	return tmp.tail != tmp.head;
 }
 
 static inline int __ticket_spin_is_contended(arch_spinlock_t *lock)
 {
 	struct __raw_tickets tmp = ACCESS_ONCE(lock->tickets);
 
-	return ((tmp.tail - tmp.head) & TICKET_MASK) > 1;
+	return (__ticket_t)(tmp.tail - tmp.head) > 1;
 }
 
 #ifndef CONFIG_PARAVIRT_SPINLOCKS
--- 3.3-rc2/arch/x86/include/asm/spinlock_types.h
+++ 3.3-rc2-x86-ticket-mask/arch/x86/include/asm/spinlock_types.h
@@ -16,7 +16,6 @@ typedef u32 __ticketpair_t;
 #endif
 
 #define TICKET_SHIFT	(sizeof(__ticket_t) * 8)
-#define TICKET_MASK	((__ticket_t)((1 << TICKET_SHIFT) - 1))
 
 typedef struct arch_spinlock {
 	union {



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