linux-kernel - [PATCH 04/14] x86/ticketlock: make large and small ticket versions of spin

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <3d2038044efd253450b17dc9df70a35d43e48bb9.1289940821.git.jeremy.fitzhardinge@citrix.com>
Date:	Tue, 16 Nov 2010 13:08:35 -0800
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Nick Piggin <npiggin@...nel.dk>,
	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	Américo Wang <xiyou.wangcong@...il.com>,
	Eric Dumazet <dada1@...mosbay.com>,
	Jan Beulich <JBeulich@...ell.com>, Avi Kivity <avi@...hat.com>,
	Xen-devel <xen-devel@...ts.xensource.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Linux Virtualization <virtualization@...ts.linux-foundation.org>,
	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
Subject: [PATCH 04/14] x86/ticketlock: make large and small ticket versions of spin_lock the same

From: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>

Make the bulk of __ticket_spin_lock look identical for large and small
number of cpus.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
---
 arch/x86/include/asm/spinlock.h |   23 ++++++++---------------
 1 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index 0170ba9..1b81809 100644
--- a/arch/x86/include/asm/spinlock.h
+++ b/arch/x86/include/asm/spinlock.h
@@ -70,19 +70,16 @@ static __always_inline void __ticket_unlock_release(struct arch_spinlock *lock)
 #if (NR_CPUS < 256)
 static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock)
 {
-	register union {
-		struct __raw_tickets tickets;
-		unsigned short slock;
-	} inc = { .slock = 1 << TICKET_SHIFT };
+	register struct __raw_tickets inc = { .tail = 1 };
 
 	asm volatile (LOCK_PREFIX "xaddw %w0, %1\n"
-		      : "+Q" (inc), "+m" (lock->slock) : : "memory", "cc");
+		      : "+r" (inc), "+m" (lock->tickets) : : "memory", "cc");
 
 	for (;;) {
-		if (inc.tickets.head == inc.tickets.tail)
+		if (inc.head == inc.tail)
 			goto out;
 		cpu_relax();
-		inc.tickets.head = ACCESS_ONCE(lock->tickets.head);
+		inc.head = ACCESS_ONCE(lock->tickets.head);
 	}
 out:	barrier();		/* make sure nothing creeps before the lock is taken */
 }
@@ -108,21 +105,17 @@ static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock)
 #else
 static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock)
 {
-	unsigned inc = 1 << TICKET_SHIFT;
-	__ticket_t tmp;
+	register struct __raw_tickets inc = { .tail = 1 };
 
 	asm volatile(LOCK_PREFIX "xaddl %0, %1\n\t"
-		     : "+r" (inc), "+m" (lock->slock)
+		     : "+r" (inc), "+m" (lock->tickets)
 		     : : "memory", "cc");
 
-	tmp = inc;
-	inc >>= TICKET_SHIFT;
-
 	for (;;) {
-		if ((__ticket_t)inc == tmp)
+		if (inc.head == inc.tail)
 			goto out;
 		cpu_relax();
-		tmp = ACCESS_ONCE(lock->tickets.head);
+		inc.head = ACCESS_ONCE(lock->tickets.head);
 	}
 out:	barrier();		/* make sure nothing creeps before the lock is taken */
 }
-- 
1.7.2.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/