Srivatsa S. Bhat [off-list ref] wrote:

We can use global rwlocks as shown below safely, without fear of deadlocks:

Readers:

         CPU 0                                CPU 1
         ------                               ------

1.    spin_lock(&random_lock);             read_lock(&my_rwlock);


2.    read_lock(&my_rwlock);               spin_lock(&random_lock);

The lock order on CPU 0 is unsafe if CPU2 can do:

	write_lock(&my_rwlock);
	spin_lock(&random_lock);

and on CPU 1 if CPU2 can do:

	spin_lock(&random_lock);
	write_lock(&my_rwlock);

I presume you were specifically excluding these situations?

David