Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull core locking updates from Ingo Molnar:
 "The main updates in this cycle were:

   - mutex MCS refactoring finishing touches: improve comments, refactor
     and clean up code, reduce debug data structure footprint, etc.

   - qrwlock finishing touches: remove old code, self-test updates.

   - small rwsem optimization

   - various smaller fixes/cleanups"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/lockdep: Revert qrwlock recusive stuff
  locking/rwsem: Avoid double checking before try acquiring write lock
  locking/rwsem: Move EXPORT_SYMBOL() lines to follow function definition
  locking/rwlock, x86: Delete unused asm/rwlock.h and rwlock.S
  locking/rwlock, x86: Clean up asm/spinlock*.h to remove old rwlock code
  locking/semaphore: Resolve some shadow warnings
  locking/selftest: Support queued rwlock
  locking/lockdep: Restrict the use of recursive read_lock() with qrwlock
  locking/spinlocks: Always evaluate the second argument of spin_lock_nested()
  locking/Documentation: Update locking/mutex-design.txt disadvantages
  locking/Documentation: Move locking related docs into Documentation/locking/
  locking/mutexes: Use MUTEX_SPIN_ON_OWNER when appropriate
  locking/mutexes: Refactor optimistic spinning code
  locking/mcs: Remove obsolete comment
  locking/mutexes: Document quick lock release when unlocking
  locking/mutexes: Standardize arguments in lock/unlock slowpaths
  locking: Remove deprecated smp_mb__() barriers

Documentation/00-INDEX

@@ -287,6 +287,8 @@ local_ops.txt
 	- semantics and behavior of local atomic operations.
 lockdep-design.txt
 	- documentation on the runtime locking correctness validator.
+locking/
+	- directory with info about kernel locking primitives
 lockstat.txt
 	- info on collecting statistics on locks (and contention).
 lockup-watchdogs.txt

Documentation/DocBook/kernel-locking.tmpl

@@ -1972,7 +1972,7 @@ machines due to caching.
    <itemizedlist>
     <listitem>
      <para>
-       <filename>Documentation/spinlocks.txt</filename>: 
+       <filename>Documentation/locking/spinlocks.txt</filename>:
        Linus Torvalds' spinlocking tutorial in the kernel sources.
      </para>
     </listitem>

Documentation/locking/lockstat.txt

@@ -12,7 +12,7 @@ Because things like lock contention can severely impact performance.
 - HOW
 
 Lockdep already has hooks in the lock functions and maps lock instances to
-lock classes. We build on that (see Documentation/lockdep-design.txt).
+lock classes. We build on that (see Documentation/lokcing/lockdep-design.txt).
 The graph below shows the relation between the lock functions and the various
 hooks therein.
 

Documentation/locking/mutex-design.txt

@@ -145,9 +145,9 @@ Disadvantages
 
 Unlike its original design and purpose, 'struct mutex' is larger than
 most locks in the kernel. E.g: on x86-64 it is 40 bytes, almost twice
-as large as 'struct semaphore' (24 bytes) and 8 bytes shy of the
+as large as 'struct semaphore' (24 bytes) and tied, along with rwsems,
-'struct rw_semaphore' variant. Larger structure sizes mean more CPU
+for the largest lock in the kernel. Larger structure sizes mean more
-cache and memory footprint.
+CPU cache and memory footprint.
 
 When to use mutexes
 -------------------

MAINTAINERS

@@ -5680,8 +5680,8 @@ M:	Ingo Molnar <mingo@redhat.com>
 L:	linux-kernel@vger.kernel.org
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core/locking
 S:	Maintained
-F:	Documentation/lockdep*.txt
+F:	Documentation/locking/lockdep*.txt
-F:	Documentation/lockstat.txt
+F:	Documentation/locking/lockstat.txt
 F:	include/linux/lockdep.h
 F:	kernel/locking/
 

arch/x86/include/asm/rwlock.h

@@ -1,49 +0,0 @@
-#ifndef _ASM_X86_RWLOCK_H
-#define _ASM_X86_RWLOCK_H
-
-#include <asm/asm.h>
-
-#if CONFIG_NR_CPUS <= 2048
-
-#ifndef __ASSEMBLY__
-typedef union {
-	s32 lock;
-	s32 write;
-} arch_rwlock_t;
-#endif
-
-#define RW_LOCK_BIAS		0x00100000
-#define READ_LOCK_SIZE(insn)	__ASM_FORM(insn##l)
-#define READ_LOCK_ATOMIC(n)	atomic_##n
-#define WRITE_LOCK_ADD(n)	__ASM_FORM_COMMA(addl n)
-#define WRITE_LOCK_SUB(n)	__ASM_FORM_COMMA(subl n)
-#define WRITE_LOCK_CMP		RW_LOCK_BIAS
-
-#else /* CONFIG_NR_CPUS > 2048 */
-
-#include <linux/const.h>
-
-#ifndef __ASSEMBLY__
-typedef union {
-	s64 lock;
-	struct {
-		u32 read;
-		s32 write;
-	};
-} arch_rwlock_t;
-#endif
-
-#define RW_LOCK_BIAS		(_AC(1,L) << 32)
-#define READ_LOCK_SIZE(insn)	__ASM_FORM(insn##q)
-#define READ_LOCK_ATOMIC(n)	atomic64_##n
-#define WRITE_LOCK_ADD(n)	__ASM_FORM(incl)
-#define WRITE_LOCK_SUB(n)	__ASM_FORM(decl)
-#define WRITE_LOCK_CMP		1
-
-#endif /* CONFIG_NR_CPUS */
-
-#define __ARCH_RW_LOCK_UNLOCKED		{ RW_LOCK_BIAS }
-
-/* Actual code is in asm/spinlock.h or in arch/x86/lib/rwlock.S */
-
-#endif /* _ASM_X86_RWLOCK_H */

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
+ * On x86, we implement read-write locks using the generic qrwlock with
- * with the high bit (sign) being the "contended" bit.
+ * 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()

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 */

arch/x86/lib/Makefile

@@ -20,7 +20,6 @@ lib-y := delay.o misc.o cmdline.o
 lib-y += thunk_$(BITS).o
 lib-y += usercopy_$(BITS).o usercopy.o getuser.o putuser.o
 lib-y += memcpy_$(BITS).o
-lib-$(CONFIG_SMP) += rwlock.o
 lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
 lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o
 

arch/x86/lib/rwlock.S

@@ -1,44 +0,0 @@
-/* Slow paths of read/write spinlocks. */
-
-#include <linux/linkage.h>
-#include <asm/alternative-asm.h>
-#include <asm/frame.h>
-#include <asm/rwlock.h>
-
-#ifdef CONFIG_X86_32
-# define __lock_ptr eax
-#else
-# define __lock_ptr rdi
-#endif
-
-ENTRY(__write_lock_failed)
-	CFI_STARTPROC
-	FRAME
-0:	LOCK_PREFIX
-	WRITE_LOCK_ADD($RW_LOCK_BIAS) (%__lock_ptr)
-1:	rep; nop
-	cmpl	$WRITE_LOCK_CMP, (%__lock_ptr)
-	jne	1b
-	LOCK_PREFIX
-	WRITE_LOCK_SUB($RW_LOCK_BIAS) (%__lock_ptr)
-	jnz	0b
-	ENDFRAME
-	ret
-	CFI_ENDPROC
-END(__write_lock_failed)
-
-ENTRY(__read_lock_failed)
-	CFI_STARTPROC
-	FRAME
-0:	LOCK_PREFIX
-	READ_LOCK_SIZE(inc) (%__lock_ptr)
-1:	rep; nop
-	READ_LOCK_SIZE(cmp) $1, (%__lock_ptr)
-	js	1b
-	LOCK_PREFIX
-	READ_LOCK_SIZE(dec) (%__lock_ptr)
-	js	0b
-	ENDFRAME
-	ret
-	CFI_ENDPROC
-END(__read_lock_failed)

drivers/gpu/drm/drm_modeset_lock.c

@@ -35,7 +35,7 @@
  * of extra utility/tracking out of our acquire-ctx.  This is provided
  * by drm_modeset_lock / drm_modeset_acquire_ctx.
  *
- * For basic principles of ww_mutex, see: Documentation/ww-mutex-design.txt
+ * For basic principles of ww_mutex, see: Documentation/locking/ww-mutex-design.txt
  *
  * The basic usage pattern is to:
  *

include/linux/atomic.h

@@ -3,42 +3,6 @@
 #define _LINUX_ATOMIC_H
 #include <asm/atomic.h>
 
-/*
- * Provide __deprecated wrappers for the new interface, avoid flag day changes.
- * We need the ugly external functions to break header recursion hell.
- */
-#ifndef smp_mb__before_atomic_inc
-static inline void __deprecated smp_mb__before_atomic_inc(void)
-{
-	extern void __smp_mb__before_atomic(void);
-	__smp_mb__before_atomic();
-}
-#endif
-
-#ifndef smp_mb__after_atomic_inc
-static inline void __deprecated smp_mb__after_atomic_inc(void)
-{
-	extern void __smp_mb__after_atomic(void);
-	__smp_mb__after_atomic();
-}
-#endif
-
-#ifndef smp_mb__before_atomic_dec
-static inline void __deprecated smp_mb__before_atomic_dec(void)
-{
-	extern void __smp_mb__before_atomic(void);
-	__smp_mb__before_atomic();
-}
-#endif
-
-#ifndef smp_mb__after_atomic_dec
-static inline void __deprecated smp_mb__after_atomic_dec(void)
-{
-	extern void __smp_mb__after_atomic(void);
-	__smp_mb__after_atomic();
-}
-#endif
-
 /**
  * atomic_add_unless - add unless the number is already a given value
  * @v: pointer of type atomic_t

include/linux/bitops.h

@@ -32,26 +32,6 @@ extern unsigned long __sw_hweight64(__u64 w);
  */
 #include <asm/bitops.h>
 
-/*
- * Provide __deprecated wrappers for the new interface, avoid flag day changes.
- * We need the ugly external functions to break header recursion hell.
- */
-#ifndef smp_mb__before_clear_bit
-static inline void __deprecated smp_mb__before_clear_bit(void)
-{
-	extern void __smp_mb__before_atomic(void);
-	__smp_mb__before_atomic();
-}
-#endif
-
-#ifndef smp_mb__after_clear_bit
-static inline void __deprecated smp_mb__after_clear_bit(void)
-{
-	extern void __smp_mb__after_atomic(void);
-	__smp_mb__after_atomic();
-}
-#endif
-
 #define for_each_set_bit(bit, addr, size) \
 	for ((bit) = find_first_bit((addr), (size));		\
 	     (bit) < (size);					\

include/linux/lockdep.h

@@ -4,7 +4,7 @@
  *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
  *
- * see Documentation/lockdep-design.txt for more details.
+ * see Documentation/locking/lockdep-design.txt for more details.
  */
 #ifndef __LINUX_LOCKDEP_H
 #define __LINUX_LOCKDEP_H

include/linux/mutex.h

@@ -52,7 +52,7 @@ struct mutex {
 	atomic_t		count;
 	spinlock_t		wait_lock;
 	struct list_head	wait_list;
-#if defined(CONFIG_DEBUG_MUTEXES) || defined(CONFIG_SMP)
+#if defined(CONFIG_DEBUG_MUTEXES) || defined(CONFIG_MUTEX_SPIN_ON_OWNER)
 	struct task_struct	*owner;
 #endif
 #ifdef CONFIG_MUTEX_SPIN_ON_OWNER
@@ -133,7 +133,7 @@ static inline int mutex_is_locked(struct mutex *lock)
 
 /*
  * See kernel/locking/mutex.c for detailed documentation of these APIs.
- * Also see Documentation/mutex-design.txt.
+ * Also see Documentation/locking/mutex-design.txt.
  */
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);