[PATCH] lockdep: spin_lock_irqsave_nested()

Introduce spin_lock_irqsave_nested(); implementation from:
 http://lkml.org/lkml/2006/6/1/122
Patch from:
 http://lkml.org/lkml/2006/9/13/258

[akpm@osdl.org: two compile fixes]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Jiri Kosina <jikos@jikos.cz>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/spinlock.h

@@ -199,6 +199,21 @@ do {								\
 		BUILD_CHECK_IRQ_FLAGS(flags);		\
 		flags = _write_lock_irqsave(lock);	\
 	} while (0)
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+#define spin_lock_irqsave_nested(lock, flags, subclass)			\
+	do {								\
+		BUILD_CHECK_IRQ_FLAGS(flags);				\
+		flags = _spin_lock_irqsave_nested(lock, subclass);	\
+	} while (0)
+#else
+#define spin_lock_irqsave_nested(lock, flags, subclass)			\
+	do {								\
+		BUILD_CHECK_IRQ_FLAGS(flags);				\
+		flags = _spin_lock_irqsave(lock);			\
+	} while (0)
+#endif
+
 #else
 #define spin_lock_irqsave(lock, flags)			\
 	do {						\
@@ -215,6 +230,9 @@ do {								\
 		BUILD_CHECK_IRQ_FLAGS(flags);		\
 		_write_lock_irqsave(lock, flags);	\
 	} while (0)
+#define spin_lock_irqsave_nested(lock, flags, subclass)	\
+	spin_lock_irqsave(lock, flags)
+
 #endif
 
 #define spin_lock_irq(lock)		_spin_lock_irq(lock)

include/linux/spinlock_api_smp.h

@@ -32,6 +32,8 @@ void __lockfunc _read_lock_irq(rwlock_t *lock)		__acquires(lock);
 void __lockfunc _write_lock_irq(rwlock_t *lock)		__acquires(lock);
 unsigned long __lockfunc _spin_lock_irqsave(spinlock_t *lock)
 							__acquires(lock);
+unsigned long __lockfunc _spin_lock_irqsave_nested(spinlock_t *lock, int subclass)
+							__acquires(lock);
 unsigned long __lockfunc _read_lock_irqsave(rwlock_t *lock)
 							__acquires(lock);
 unsigned long __lockfunc _write_lock_irqsave(rwlock_t *lock)

kernel/spinlock.c

@@ -293,6 +293,27 @@ void __lockfunc _spin_lock_nested(spinlock_t *lock, int subclass)
 }
 
 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_);
+	/*
+	 * On lockdep we dont want the hand-coded irq-enable of
+	 * _raw_spin_lock_flags() code, because lockdep assumes
+	 * that interrupts are not re-enabled during lock-acquire:
+	 */
+#ifdef CONFIG_PROVE_SPIN_LOCKING
+	_raw_spin_lock(lock);
+#else
+	_raw_spin_lock_flags(lock, &flags);
+#endif
+	return flags;
+}
+
+EXPORT_SYMBOL(_spin_lock_irqsave_nested);
 
 #endif