[patch 2/2] locking: Reduce ifdefs in kernel/spinlock.c

Thomas Gleixner
2009-11-09T15:22:03Z

[-- Attachment #1: locking-simplify-spinlock-c.patch --]
[-- Type: text/plain, Size: 9262 bytes --]

With the Kconfig based inline decisions we can remove extra ifdefs in
kernel/spinlock.c by creating the complex lockbreak functions as
inlines which are inserted into the non inlined lock functions.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: linux-arch@vger.kernel.org
---
kernel/spinlock.c | 260 ++++++++++++++++++++++++++----------------------------
1 file changed, 128 insertions(+), 132 deletions(-)

Index: linux-2.6/kernel/spinlock.c
===================================================================
--- linux-2.6.orig/kernel/spinlock.c
+++ linux-2.6/kernel/spinlock.c
@@ -21,6 +21,133 @@
#include <linux/debug_locks.h>
#include <linux/module.h>

+/*
+ * If lockdep is enabled then we use the non-preemption spin-ops
+ * even on CONFIG_PREEMPT, because lockdep assumes that interrupts are
+ * not re-enabled during lock-acquire (which the preempt-spin-ops do):
+ */
+#if !defined(CONFIG_GENERIC_LOCKBREAK) || defined(CONFIG_DEBUG_LOCK_ALLOC)
+/*
+ * The __lock_function inlines are taken from
+ * include/linux/spinlock_api_smp.h
+ */
+#else
+/*
+ * We build the __lock_function inlines here. They are too large for
+ * inlining all over the place, but here is only one user per function
+ * which embedds them into the calling _lock_function below.
+ *
+ * This could be a long-held lock. We both prepare to spin for a long
+ * time (making _this_ CPU preemptable if possible), and we also signal
+ * towards that other CPU that it should break the lock ASAP.
+ */
+#define BUILD_LOCK_OPS(op, locktype) \
+void __lockfunc __##op##_lock(locktype##_t *lock) \
+{ \
+ for (;;) { \
+ preempt_disable(); \
+ if (likely(_raw_##op##_trylock(lock))) \
+ break; \
+ preempt_enable(); \
+ \
+ if (!(lock)->break_lock) \
+ (lock)->break_lock = 1; \
+ while (!op##_can_lock(lock) && (lock)->break_lock) \
+ _raw_##op##_relax(&lock->raw_lock); \
+ } \
+ (lock)->break_lock = 0; \
+} \
+ \
+unsigned long __lockfunc __##op##_lock_irqsave(locktype##_t *lock) \
+{ \
+ unsigned long flags; \
+ \
+ for (;;) { \
+ preempt_disable(); \
+ local_irq_save(flags); \
+ if (likely(_raw_##op##_trylock(lock))) \
+ break; \
+ local_irq_restore(flags); \
+ preempt_enable(); \
+ \
+ if (!(lock)->break_lock) \
+ (lock)->break_lock = 1; \
+ while (!op##_can_lock(lock) && (lock)->break_lock) \
+ _raw_##op##_relax(&lock->raw_lock); \
+ } \
+ (lock)->break_lock = 0; \
+ return flags; \
+} \
+ \
+void __lockfunc __##op##_lock_irq(locktype##_t *lock) \
+{ \
+ _##op##_lock_irqsave(lock); \
+} \
+ \
+void __lockfunc __##op##_lock_bh(locktype##_t *lock) \
+{ \
+ unsigned long flags; \
+ \
+ /* */ \
+ /* Careful: we must exclude softirqs too, hence the */ \
+ /* irq-disabling. We use the generic preemption-aware */ \
+ /* function: */ \
+ /**/ \
+ flags = _##op##_lock_irqsave(lock); \
+ local_bh_disable(); \
+ local_irq_restore(flags); \
+} \
+
+/*
+ * Build preemption-friendly versions of the following
+ * lock-spinning functions:
+ *
+ * __[spin|read|write]_lock()
+ * __[spin|read|write]_lock_irq()
+ * __[spin|read|write]_lock_irqsave()
+ * __[spin|read|write]_lock_bh()
+ */
+BUILD_LOCK_OPS(spin, spinlock);
+BUILD_LOCK_OPS(read, rwlock);
+BUILD_LOCK_OPS(write, rwlock);
+
+#endif
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+
+void __lockfunc _spin_lock_nested(spinlock_t *lock, int subclass)
+{
+ preempt_disable();
+ spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
+ LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
+}
+EXPORT_SYMBOL(_spin_lock_nested);
+
+unsigned long __lockfunc _spin_lock_irqsave_nested(spinlock_t *lock,
+ int subclass)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ preempt_disable();
+ spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
+ LOCK_CONTENDED_FLAGS(lock, _raw_spin_trylock, _raw_spin_lock,
+ _raw_spin_lock_flags, &flags);
+ return flags;
+}
+EXPORT_SYMBOL(_spin_lock_irqsave_nested);
+
+void __lockfunc _spin_lock_nest_lock(spinlock_t *lock,
+ struct lockdep_map *nest_lock)
+{
+ preempt_disable();
+ spin_acquire_nest(&lock->dep_map, 0, 0, nest_lock, _RET_IP_);
+ LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
+}
+EXPORT_SYMBOL(_spin_lock_nest_lock);
+
+#endif
+
#ifndef CONFIG_INLINE_SPIN_TRYLOCK
int __lockfunc _spin_trylock(spinlock_t *lock)
{
@@ -45,13 +172,6 @@ int __lockfunc _write_trylock(rwlock_t *
EXPORT_SYMBOL(_write_trylock);
#endif

-/*
- * If lockdep is enabled then we use the non-preemption spin-ops
- * even on CONFIG_PREEMPT, because lockdep assumes that interrupts are
- * not re-enabled during lock-acquire (which the preempt-spin-ops do):
- */
-#if !defined(CONFIG_GENERIC_LOCKBREAK) || defined(CONFIG_DEBUG_LOCK_ALLOC)
-
#ifndef CONFIG_INLINE_READ_LOCK
void __lockfunc _read_lock(rwlock_t *lock)
{
@@ -148,130 +268,6 @@ void __lockfunc _write_lock(rwlock_t *lo
EXPORT_SYMBOL(_write_lock);
#endif

-#else /* CONFIG_PREEMPT: */
-
-/*
- * This could be a long-held lock. We both prepare to spin for a long
- * time (making _this_ CPU preemptable if possible), and we also signal
- * towards that other CPU that it should break the lock ASAP.
- *
- * (We do this in a function because inlining it would be excessive.)
- */
-
-#define BUILD_LOCK_OPS(op, locktype) \
-void __lockfunc _##op##_lock(locktype##_t *lock) \
-{ \
- for (;;) { \
- preempt_disable(); \
- if (likely(_raw_##op##_trylock(lock))) \
- break; \
- preempt_enable(); \
- \
- if (!(lock)->break_lock) \
- (lock)->break_lock = 1; \
- while (!op##_can_lock(lock) && (lock)->break_lock) \
- _raw_##op##_relax(&lock->raw_lock); \
- } \
- (lock)->break_lock = 0; \
-} \
- \
-EXPORT_SYMBOL(_##op##_lock); \
- \
-unsigned long __lockfunc _##op##_lock_irqsave(locktype##_t *lock) \
-{ \
- unsigned long flags; \
- \
- for (;;) { \
- preempt_disable(); \
- local_irq_save(flags); \
- if (likely(_raw_##op##_trylock(lock))) \
- break; \
- local_irq_restore(flags); \
- preempt_enable(); \
- \
- if (!(lock)->break_lock) \
- (lock)->break_lock = 1; \
- while (!op##_can_lock(lock) && (lock)->break_lock) \
- _raw_##op##_relax(&lock->raw_lock); \
- } \
- (lock)->break_lock = 0; \
- return flags; \
-} \
- \
-EXPORT_SYMBOL(_##op##_lock_irqsave); \
- \
-void __lockfunc _##op##_lock_irq(locktype##_t *lock) \
-{ \
- _##op##_lock_irqsave(lock); \
-} \
- \
-EXPORT_SYMBOL(_##op##_lock_irq); \
- \
-void __lockfunc _##op##_lock_bh(locktype##_t *lock) \
-{ \
- unsigned long flags; \
- \
- /* */ \
- /* Careful: we must exclude softirqs too, hence the */ \
- /* irq-disabling. We use the generic preemption-aware */ \
- /* function: */ \
- /**/ \
- flags = _##op##_lock_irqsave(lock); \
- local_bh_disable(); \
- local_irq_restore(flags); \
-} \
- \
-EXPORT_SYMBOL(_##op##_lock_bh)
-
-/*
- * Build preemption-friendly versions of the following
- * lock-spinning functions:
- *
- * _[spin|read|write]_lock()
- * _[spin|read|write]_lock_irq()
- * _[spin|read|write]_lock_irqsave()
- * _[spin|read|write]_lock_bh()
- */
-BUILD_LOCK_OPS(spin, spinlock);
-BUILD_LOCK_OPS(read, rwlock);
-BUILD_LOCK_OPS(write, rwlock);
-
-#endif /* CONFIG_PREEMPT */
-
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-
-void __lockfunc _spin_lock_nested(spinlock_t *lock, int subclass)
-{
- preempt_disable();
- spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
- LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
-}
-EXPORT_SYMBOL(_spin_lock_nested);
-
-unsigned long __lockfunc _spin_lock_irqsave_nested(spinlock_t *lock, int subclass)
-{
- unsigned long flags;
-
- local_irq_save(flags);
- preempt_disable();
- spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
- LOCK_CONTENDED_FLAGS(lock, _raw_spin_trylock, _raw_spin_lock,
- _raw_spin_lock_flags, &flags);
- return flags;
-}
-EXPORT_SYMBOL(_spin_lock_irqsave_nested);
-
-void __lockfunc _spin_lock_nest_lock(spinlock_t *lock,
- struct lockdep_map *nest_lock)
-{
- preempt_disable();
- spin_acquire_nest(&lock->dep_map, 0, 0, nest_lock, _RET_IP_);
- LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
-}
-EXPORT_SYMBOL(_spin_lock_nest_lock);
-
-#endif
-
#ifndef CONFIG_INLINE_SPIN_UNLOCK
void __lockfunc _spin_unlock(spinlock_t *lock)
{
@@ -296,7 +292,7 @@ void __lockfunc _read_unlock(rwlock_t *l
EXPORT_SYMBOL(_read_unlock);
#endif

-#ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQRESTORE
+#ifndef CONFIG_INLINE_SPIN_UNLOCK_RESTORE
void __lockfunc _spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
{
__spin_unlock_irqrestore(lock, flags);