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Message-Id: <1408037251-45918-2-git-send-email-Waiman.Long@hp.com>
Date: Thu, 14 Aug 2014 13:27:30 -0400
From: Waiman Long <Waiman.Long@...com>
To: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...nel.org>,
"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
Peter Zijlstra <peterz@...radead.org>,
Scott J Norton <scott.norton@...com>,
Waiman Long <Waiman.Long@...com>
Subject: [PATCH 1/2] rwlock, x86: clean up asm/spinlock*.h to remove old rwlock code
As the x86 architecture now uses qrwlock for its read/write lock
implementation, it is no longer necessary to keep the old rwlock code
around. This patch removes the old rwlock code in the asm/spinlock.h
and asm/spinlock_types.h files. Now the ARCH_USE_QUEUE_RWLOCK
config parameter cannot be removed from x86/Kconfig or there will be
compilation error.
Signed-off-by: Waiman Long <Waiman.Long@...com>
---
arch/x86/include/asm/spinlock.h | 81 +--------------------------------
arch/x86/include/asm/spinlock_types.h | 4 --
2 files changed, 2 insertions(+), 83 deletions(-)
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index 54f1c80..9295016 100644
--- a/arch/x86/include/asm/spinlock.h
+++ b/arch/x86/include/asm/spinlock.h
@@ -187,7 +187,6 @@ 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.
@@ -198,91 +197,15 @@ static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
* irq-safe write-lock, but readers can get non-irqsafe
* read-locks.
*
- * On x86, we implement read-write locks as a 32-bit counter
- * with the high bit (sign) being the "contended" bit.
+ * On x86, we implement read-write locks using the generic qrwlock with
+ * x86 specific optimization.
*/
-/**
- * read_can_lock - would read_trylock() succeed?
- * @lock: the rwlock in question.
- */
-static inline int arch_read_can_lock(arch_rwlock_t *lock)
-{
- return lock->lock > 0;
-}
-
-/**
- * write_can_lock - would write_trylock() succeed?
- * @lock: the rwlock in question.
- */
-static inline int arch_write_can_lock(arch_rwlock_t *lock)
-{
- return lock->write == WRITE_LOCK_CMP;
-}
-
-static inline void arch_read_lock(arch_rwlock_t *rw)
-{
- asm volatile(LOCK_PREFIX READ_LOCK_SIZE(dec) " (%0)\n\t"
- "jns 1f\n"
- "call __read_lock_failed\n\t"
- "1:\n"
- ::LOCK_PTR_REG (rw) : "memory");
-}
-
-static inline void arch_write_lock(arch_rwlock_t *rw)
-{
- asm volatile(LOCK_PREFIX WRITE_LOCK_SUB(%1) "(%0)\n\t"
- "jz 1f\n"
- "call __write_lock_failed\n\t"
- "1:\n"
- ::LOCK_PTR_REG (&rw->write), "i" (RW_LOCK_BIAS)
- : "memory");
-}
-
-static inline int arch_read_trylock(arch_rwlock_t *lock)
-{
- READ_LOCK_ATOMIC(t) *count = (READ_LOCK_ATOMIC(t) *)lock;
-
- if (READ_LOCK_ATOMIC(dec_return)(count) >= 0)
- return 1;
- READ_LOCK_ATOMIC(inc)(count);
- return 0;
-}
-
-static inline int arch_write_trylock(arch_rwlock_t *lock)
-{
- atomic_t *count = (atomic_t *)&lock->write;
-
- if (atomic_sub_and_test(WRITE_LOCK_CMP, count))
- return 1;
- atomic_add(WRITE_LOCK_CMP, count);
- return 0;
-}
-
-static inline void arch_read_unlock(arch_rwlock_t *rw)
-{
- asm volatile(LOCK_PREFIX READ_LOCK_SIZE(inc) " %0"
- :"+m" (rw->lock) : : "memory");
-}
-
-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");
-}
-#else
#include <asm/qrwlock.h>
-#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)
-#undef READ_LOCK_SIZE
-#undef READ_LOCK_ATOMIC
-#undef WRITE_LOCK_ADD
-#undef WRITE_LOCK_SUB
-#undef WRITE_LOCK_CMP
-
#define arch_spin_relax(lock) cpu_relax()
#define arch_read_relax(lock) cpu_relax()
#define arch_write_relax(lock) cpu_relax()
diff --git a/arch/x86/include/asm/spinlock_types.h b/arch/x86/include/asm/spinlock_types.h
index 73c4c00..5f9d757 100644
--- a/arch/x86/include/asm/spinlock_types.h
+++ b/arch/x86/include/asm/spinlock_types.h
@@ -34,10 +34,6 @@ typedef struct arch_spinlock {
#define __ARCH_SPIN_LOCK_UNLOCKED { { 0 } }
-#ifdef CONFIG_QUEUE_RWLOCK
#include <asm-generic/qrwlock_types.h>
-#else
-#include <asm/rwlock.h>
-#endif
#endif /* _ASM_X86_SPINLOCK_TYPES_H */
--
1.7.1
--
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