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Subject[patch 2.6.25-rc3] lockdep: add spin_lock_irq_nested()
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> > >     ==> LOCKDEP feature is evidently missing:
> > >             spin_lock_irq_nested(lock_ptr, lock_class)
> >
> > This rant is more lines than adding the API :-/ the reason for it not
> > being there is simple, it wasn't needed up until now.
>
> I suspected that was the case, but for all I knew there was some
> religious objection.

Does this look about right? Or, I suppose it could just call
the _spin_lock_irqsave_nested() routine and discard the result.

- Dave

========= CUT HERE
Add new spin_lock_irq_nested() call, so that lockdep can work with the
code which uses spin_*_irq() calls that don't save/restore flags.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
Against 2.6.25-rc3
include/linux/spinlock.h | 6 ++++++
include/linux/spinlock_api_smp.h | 2 ++
kernel/spinlock.c | 21 +++++++++++++++++++--
3 files changed, 27 insertions(+), 2 deletions(-)
--- a/include/linux/spinlock.h 2008-02-24 18:50:50.000000000 -0800
+++ b/include/linux/spinlock.h 2008-02-24 19:02:39.000000000 -0800
@@ -196,9 +196,13 @@ do { \
#define write_lock_irqsave(lock, flags) flags = _write_lock_irqsave(lock)

#ifdef CONFIG_DEBUG_LOCK_ALLOC
+#define spin_lock_irq_nested(lock, subclass) \
+ _spin_lock_irq_nested(lock, subclass)
#define spin_lock_irqsave_nested(lock, flags, subclass) \
flags = _spin_lock_irqsave_nested(lock, subclass)
#else
+#define spin_lock_irq_nested(lock, subclass) \
+ _spin_lock_irq(lock)
#define spin_lock_irqsave_nested(lock, flags, subclass) \
flags = _spin_lock_irqsave(lock)
#endif
@@ -208,6 +212,8 @@ do { \
#define spin_lock_irqsave(lock, flags) _spin_lock_irqsave(lock, flags)
#define read_lock_irqsave(lock, flags) _read_lock_irqsave(lock, flags)
#define write_lock_irqsave(lock, flags) _write_lock_irqsave(lock, flags)
+#define spin_lock_irq_nested(lock, subclass) \
+ spin_lock_irq(lock)
#define spin_lock_irqsave_nested(lock, flags, subclass) \
spin_lock_irqsave(lock, flags)

--- a/include/linux/spinlock_api_smp.h 2008-02-24 18:50:50.000000000 -0800
+++ b/include/linux/spinlock_api_smp.h 2008-02-24 19:02:39.000000000 -0800
@@ -28,6 +28,8 @@ void __lockfunc _spin_lock_bh(spinlock_t
void __lockfunc _read_lock_bh(rwlock_t *lock) __acquires(lock);
void __lockfunc _write_lock_bh(rwlock_t *lock) __acquires(lock);
void __lockfunc _spin_lock_irq(spinlock_t *lock) __acquires(lock);
+void __lockfunc _spin_lock_irq_nested(spinlock_t *lock, int subclass)
+ __acquires(lock);
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)
--- a/kernel/spinlock.c 2008-02-24 18:50:50.000000000 -0800
+++ b/kernel/spinlock.c 2008-02-24 19:02:39.000000000 -0800
@@ -290,8 +290,26 @@ void __lockfunc _spin_lock_nested(spinlo
spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
}
-
EXPORT_SYMBOL(_spin_lock_nested);
+
+void __lockfunc _spin_lock_irq_nested(spinlock_t *lock, int subclass)
+{
+ local_irq_disable();
+ 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_LOCKDEP
+ LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
+#else
+ _raw_spin_lock_flags(lock, &flags);
+#endif
+}
+EXPORT_SYMBOL(_spin_lock_irq_nested);
+
unsigned long __lockfunc _spin_lock_irqsave_nested(spinlock_t *lock, int subclass)
{
unsigned long flags;
@@ -311,7 +329,6 @@ unsigned long __lockfunc _spin_lock_irqs
#endif
return flags;
}
-
EXPORT_SYMBOL(_spin_lock_irqsave_nested);

#endif
--
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