* Keith Owens <[email protected]> wrote:
> 2.6.13-rc1 built with SMP=Y and DEBUG_SPINLOCK=y. That uses
> kernel/spinlock.c instead of the inline definitions of the spinlock
> functions. Alas only the inline definitions test for
> DEBUG_SPINLOCK=y, none of the code in in spinlock.c has any debug
> facilities.
the spinlock cleanups in -mm (not yet in -git) obsolete most of the
debugging approach of the current kernel.
but even in terms of 2.6.13-rc1, i'm not completely sure what you mean.
Yes, there's no debugging code in kernel/spinlock.c because much of the
DEBUG_SPINLOCK code (under the old method) is located in the arch
spinlock.h files. I.e. on x86 you'll get SMP spinlock debugging from
asm-i386/spinlock.h:
static inline void _raw_spin_lock(spinlock_t *lock)
{
#ifdef CONFIG_DEBUG_SPINLOCK
if (unlikely(lock->magic != SPINLOCK_MAGIC)) {
printk("eip: %p\n", __builtin_return_address(0));
BUG();
}
#endif
the only practical exception is when CONFIG_PREEMPT is enabled: the arch
level trylock, upon which the PREEMPT spinlocks rely on heavily, has no
meaningful DEBUG_SPINLOCK checks. (but PREEMPT has other checks which
partly offset this.) In any case, this too is fixed by my spinlock
cleanups - there all debugging is done centrally in
lib/spinlock_debug.c.
Ingo
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