On Thu, 31 Jan 2013 22:49:49 +0100
Jan Kara <jack@xxxxxxx> wrote:
> Implement range locking using interval tree.
>
> ...
>
> +void range_lock(struct range_lock_tree *tree, struct range_lock *lock)
> +{
> + struct interval_tree_node *node;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&tree->lock, flags);
> + node = interval_tree_iter_first(&tree->root, lock->node.start,
> + lock->node.last);
> + while (node) {
> + lock->blocking_ranges++;
> + node = interval_tree_iter_next(node, lock->node.start,
> + lock->node.last);
> + }
> + interval_tree_insert(&lock->node, &tree->root);
> + /* Do we need to go to sleep? */
> + while (lock->blocking_ranges) {
> + lock->task = current;
> + __set_current_state(TASK_UNINTERRUPTIBLE);
> + spin_unlock_irqrestore(&tree->lock, flags);
> + schedule();
> + spin_lock_irqsave(&tree->lock, flags);
> + }
> + spin_unlock_irqrestore(&tree->lock, flags);
> +}
>
> ...
>
> +void range_unlock(struct range_lock_tree *tree, struct range_lock *lock)
> +{
> + struct interval_tree_node *node;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&tree->lock, flags);
> + interval_tree_remove(&lock->node, &tree->root);
> + node = interval_tree_iter_first(&tree->root, lock->node.start,
> + lock->node.last);
> + while (node) {
> + range_lock_unblock((struct range_lock *)node);
> + node = interval_tree_iter_next(node, lock->node.start,
> + lock->node.last);
> + }
> + spin_unlock_irqrestore(&tree->lock, flags);
> +}
What are the worst-case interrupt-off durations here?
I note that the new exported functions in this patchset are
refreshingly free of documentation ;)
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