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Subject[PATCH 2/3] Synaptics - fix lockdep warnings
This patch introduces spin_lock_irqsave_nested(), as it is needed when 
annotating nested irqsave-spinlocks for lockdep.

This is needed to cope with serio_interrupt() being recursively called
from synaptics_pass_pt_packet(). More users could arise.

Implementation stolen from Arjan [1], whose patch didn't make it neither
into mainline nor -mm.

If applicable, please apply.

[1] http://lkml.org/lkml/2006/6/1/122

Signed-off-by: Jiri Kosina <jikos@jikos.cz>

diff -rup linux-2.6.18-rc6-mm2.orig/include/linux/spinlock_api_smp.h linux-2.6.18-rc6-mm2/include/linux/spinlock_api_smp.h
--- linux-2.6.18-rc6-mm2.orig/include/linux/spinlock_api_smp.h 2006-09-14 00:49:35.000000000 +0200
+++ linux-2.6.18-rc6-mm2/include/linux/spinlock_api_smp.h 2006-09-14 01:24:08.000000000 +0200
@@ -32,6 +32,8 @@ void __lockfunc _read_lock_irq(rwlock_t
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(spinlock_t);
unsigned long __lockfunc _read_lock_irqsave(rwlock_t *lock)
__acquires(lock);
unsigned long __lockfunc _write_lock_irqsave(rwlock_t *lock)
diff -rup linux-2.6.18-rc6-mm2.orig/include/linux/spinlock_api_up.h linux-2.6.18-rc6-mm2/include/linux/spinlock_api_up.h
--- linux-2.6.18-rc6-mm2.orig/include/linux/spinlock_api_up.h 2006-09-04 04:19:48.000000000 +0200
+++ linux-2.6.18-rc6-mm2/include/linux/spinlock_api_up.h 2006-09-14 01:24:05.000000000 +0200
@@ -59,6 +59,7 @@
#define _read_lock_irq(lock) __LOCK_IRQ(lock)
#define _write_lock_irq(lock) __LOCK_IRQ(lock)
#define _spin_lock_irqsave(lock, flags) __LOCK_IRQSAVE(lock, flags)
+#define _spin_lock_irqsave_nested(lock, flags, subclass) __LOCK_IRQSAVE(lock, flags, subclass)
#define _read_lock_irqsave(lock, flags) __LOCK_IRQSAVE(lock, flags)
#define _write_lock_irqsave(lock, flags) __LOCK_IRQSAVE(lock, flags)
#define _spin_trylock(lock) ({ __LOCK(lock); 1; })
diff -rup linux-2.6.18-rc6-mm2.orig/include/linux/spinlock.h linux-2.6.18-rc6-mm2/include/linux/spinlock.h
--- linux-2.6.18-rc6-mm2.orig/include/linux/spinlock.h 2006-09-14 00:49:35.000000000 +0200
+++ linux-2.6.18-rc6-mm2/include/linux/spinlock.h 2006-09-14 01:24:12.000000000 +0200
@@ -186,6 +186,11 @@ do { \
#define spin_lock_irqsave(lock, flags) flags = _spin_lock_irqsave(lock)
#define read_lock_irqsave(lock, flags) flags = _read_lock_irqsave(lock)
#define write_lock_irqsave(lock, flags) flags = _write_lock_irqsave(lock)
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+#define spin_lock_irqsave_nested(lock, flags, subclass) flags = _spin_lock_irqsave_nested(lock, subclass)
+#else
+#define spin_lock_irqsave_nested(lock, flags, subclass) flags = _spin_lock_irqsave(lock)
+#endif
#else
#define spin_lock_irqsave(lock, flags) _spin_lock_irqsave(lock, flags)
#define read_lock_irqsave(lock, flags) _read_lock_irqsave(lock, flags)
diff -rup linux-2.6.18-rc6-mm2.orig/kernel/spinlock.c linux-2.6.18-rc6-mm2/kernel/spinlock.c
--- linux-2.6.18-rc6-mm2.orig/kernel/spinlock.c 2006-09-14 00:49:35.000000000 +0200
+++ linux-2.6.18-rc6-mm2/kernel/spinlock.c 2006-09-14 01:27:17.000000000 +0200
@@ -304,6 +304,27 @@ void __lockfunc _spin_lock_nested(spinlo
}

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, subtype, 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

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