Re: [PATCH] i386 spinlocks should use the full 32 bits, not only 8 bits

[Ingo Molnar <mingo@elte.hu>]

* Linus Torvalds <torvalds@osdl.org> wrote:

> 
> 
> On Fri, 21 Oct 2005, Ingo Molnar wrote:
> > 
> > the unlock is simple even in the preemption case
> 
> No it's not. It needs to decrement the preemption counter and test it.

arghhh. Right you are. I even had the proper solution coded up initially 
(i had || defined(CONFIG_PREEMPT)) but dropped it due to fatal brain 
error. Been hacking on way too much ktimer code today ... Hopefully 
better patch attached. Booted on SMP+PREEMPT x86. But i'd really advise 
you against taking patches from me tonight :-|

	Ingo

Signed-off-by: Ingo Molnar <mingo@elte.hu>

 include/linux/spinlock.h |   15 ++++++++++++---
 1 files changed, 12 insertions(+), 3 deletions(-)

Index: linux/include/linux/spinlock.h
===================================================================
--- linux.orig/include/linux/spinlock.h
+++ linux/include/linux/spinlock.h
@@ -171,9 +171,18 @@ extern int __lockfunc generic__raw_read_
 #define write_lock_irq(lock)		_write_lock_irq(lock)
 #define write_lock_bh(lock)		_write_lock_bh(lock)
 
-#define spin_unlock(lock)		_spin_unlock(lock)
-#define write_unlock(lock)		_write_unlock(lock)
-#define read_unlock(lock)		_read_unlock(lock)
+/*
+ * We inline the unlock functions in the nondebug case:
+ */
+#if defined(CONFIG_DEBUG_SPINLOCK) || defined(CONFIG_PREEMPT)
+# define spin_unlock(lock)		_spin_unlock(lock)
+# define read_unlock(lock)		_read_unlock(lock)
+# define write_unlock(lock)		_write_unlock(lock)
+#else
+# define spin_unlock(lock)		__raw_spin_unlock(&(lock)->raw_lock)
+# define read_unlock(lock)		__raw_read_unlock(&(lock)->raw_lock)
+# define write_unlock(lock)		__raw_write_unlock(&(lock)->raw_lock)
+#endif
 
 #define spin_unlock_irqrestore(lock, flags) \
 					_spin_unlock_irqrestore(lock, flags)