From: Waiman Long <Waiman.Long@hp.com>
Date: Thu, 14 Aug 2014 17:27:30 +0000 (-0400)
Subject: locking/rwlock, x86: Clean up asm/spinlock*.h to remove old rwlock code
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=2ff810a7ef38b55ba6c7b80bb7ff22847fd3be69;p=linux-beck.git

locking/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
a compilation error.

Signed-off-by: Waiman Long <Waiman.Long@hp.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Waiman Long <Waiman.Long@hp.com>
Link: http://lkml.kernel.org/r/1408037251-45918-2-git-send-email-Waiman.Long@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index 54f1c8068c02..9295016485c9 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 73c4c007200f..5f9d7572d82b 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 */