[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>

3 files changed, 41 insertions, 0 deletions

diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
index 54ad37089c49..57f670d78f7c 100644
--- a/include/linux/spinlock.h
+++ b/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)
diff --git a/include/linux/spinlock_api_smp.h b/include/linux/spinlock_api_smp.h
index 8828b8155e9c..8a2307ce7296 100644
--- a/include/linux/spinlock_api_smp.h
+++ b/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)
diff --git a/kernel/spinlock.c b/kernel/spinlock.c
index 476c3741511b..2c6c2bf85514 100644
--- a/kernel/spinlock.c
+++ b/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