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From: Arnd Bergmann <arnd@bergmann-dalldorf.de>
To: Jesse Barnes <jbarnes@sgi.com>, Daniel Phillips <phillips@arcor.de>
Subject: Re: spinlock assertion macros
Date: Thu, 11 Jul 2002 12:51:38 +0200
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On Thursday 11 July 2002 01:36, Jesse Barnes wrote:

+#define spin_assert_unlocked(lock) if (spin_is_locked(lock)) { printk("lock assertion failure: lock at %s:%d should be unlocked!\n", __FILE__, __LINE__); }

I suppose what would at least be as helpful is to check if _any_ 
lock is held, e.g. when calling a potentially sleeping function.

Something along these lines:

#ifdef CONFIG_DEBUG_SPINLOCK
extern char *volatile last_spinlock[NR_CPUS];

#define spin_assert_unlocked_all() ({ \
	char *lock = last_spinlock[smp_processor_id()]; \
	if (lock) { \
		printk (KERN_CRIT "%s:%d: lock %s is held\n", \
			__func__, __LINE__, lock); \
		BUG(); \
	} \
})

#define spin_lock(lock) ({ \
	last_spinlock[smp_processor_id()] = __stringify(lock) "@" \
		__FILE__ ":" __stringify(__LINE__); \
	__really_spin_lock(lock); \
})
#endif

probably, a per-cpu lock depth should be used to also catch
spin_lock(foo_lock); 
spin_lock(bar_lock); 
spin_unlock(bar_lock);
spin_assert_unlock_all();

	Arnd <><
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