linux-kernel - [PATCH v7 2/4] qrwlock x86: Enable x86 to use queue read/write lock

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: <1385147087-26588-3-git-send-email-Waiman.Long@hp.com>
Date:	Fri, 22 Nov 2013 14:04:45 -0500
From:	Waiman Long <Waiman.Long@...com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Arnd Bergmann <arnd@...db.de>
Cc:	linux-arch@...r.kernel.org, x86@...nel.org,
	linux-kernel@...r.kernel.org,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Michel Lespinasse <walken@...gle.com>,
	Andi Kleen <andi@...stfloor.org>,
	Rik van Riel <riel@...hat.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>,
	George Spelvin <linux@...izon.com>,
	Tim Chen <tim.c.chen@...ux.intel.com>,
	"Aswin Chandramouleeswaran\"" <aswin@...com>,
	Scott J Norton <scott.norton@...com>,
	Waiman Long <Waiman.Long@...com>
Subject: [PATCH v7 2/4] qrwlock x86: Enable x86 to use queue read/write lock

This patch makes the necessary changes at the x86 architecture specific
layer to enable the presence of the CONFIG_QUEUE_RWLOCK kernel option
to replace the read/write lock by the queue read/write lock.

It also enables the CONFIG_QUEUE_RWLOCK option by default for x86 which
will force the use of queue read/write lock. That will greatly improve
the fairness of read/write lock and eliminate live-lock situation
where one task may not get the lock for an indefinite period of time.

Signed-off-by: Waiman Long <Waiman.Long@...com>
---
 arch/x86/Kconfig                      |    1 +
 arch/x86/include/asm/spinlock.h       |    2 ++
 arch/x86/include/asm/spinlock_types.h |    4 ++++
 3 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e903c71..c4a9c54 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -124,6 +124,7 @@ config X86
 	select RTC_LIB
 	select HAVE_DEBUG_STACKOVERFLOW
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
+	select QUEUE_RWLOCK
 
 config INSTRUCTION_DECODER
 	def_bool y
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index bf156de..8fb88c5 100644
--- a/arch/x86/include/asm/spinlock.h
+++ b/arch/x86/include/asm/spinlock.h
@@ -188,6 +188,7 @@ static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
 		cpu_relax();
 }
 
+#ifndef CONFIG_QUEUE_RWLOCK
 /*
  * Read-write spinlocks, allowing multiple readers
  * but only one writer.
@@ -270,6 +271,7 @@ static inline void arch_write_unlock(arch_rwlock_t *rw)
 	asm volatile(LOCK_PREFIX WRITE_LOCK_ADD(%1) "%0"
 		     : "+m" (rw->write) : "i" (RW_LOCK_BIAS) : "memory");
 }
+#endif /* CONFIG_QUEUE_RWLOCK */
 
 #define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
 #define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
diff --git a/arch/x86/include/asm/spinlock_types.h b/arch/x86/include/asm/spinlock_types.h
index 4f1bea1..a585635 100644
--- a/arch/x86/include/asm/spinlock_types.h
+++ b/arch/x86/include/asm/spinlock_types.h
@@ -34,6 +34,10 @@ typedef struct arch_spinlock {
 
 #define __ARCH_SPIN_LOCK_UNLOCKED	{ { 0 } }
 
+#ifdef CONFIG_QUEUE_RWLOCK
+#include <asm-generic/qrwlock.h>
+#else
 #include <asm/rwlock.h>
+#endif
 
 #endif /* _ASM_X86_SPINLOCK_TYPES_H */
-- 
1.7.1

--
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/