David Howells [off-list ref] wrote:

quoted

Any reason why you're setting up your own style of waitqueue in
mutex-simple.c instead of just using the kernel's style of waitqueue?

Because I can steal the code from FRV's semaphores or rw-semaphores, and this
way I can be sure of what I'm doing.

And because:

	struct mutex {
		int			state;
		wait_queue_head_t	wait_queue;
	};

Wastes 8 more bytes of memory than:

	struct mutex {
		int			state;
		spinlock_t		wait_lock;
		struct list_head	wait_list;
	};

on a 64-bit machine if spinlock_t is 4 bytes. Both waste 4 bytes if spinlock_t
is 8 bytes.

David