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SubjectRe: [PATCH 2/6] locking: Introduce range reader/writer lock
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On 20/04/2017 18:01, Davidlohr Bueso wrote:
>>> +int range_read_trylock(struct range_rwlock_tree *tree, struct
>>> range_rwlock *lock)
>>> +{
>>> + int ret = true;
>>> + unsigned long flags;
>>> + struct interval_tree_node *node;
>>> +
>>> + spin_lock_irqsave(&tree->lock, flags);
>>> +
>>> + if (!__range_intersects_intree(tree, lock))
>>> + goto insert;
>>> +
>>> + /*
>>> + * We have overlapping ranges in the tree, ensure that we can
>>> + * in fact share the lock.
>>> + */
>>> + range_interval_tree_foreach(node, &tree->root,
>>> + lock->node.start, lock->node.last) {
>>> + struct range_rwlock *blocked_lock;
>>> + blocked_lock = range_entry(node, struct range_rwlock, node);
>>> +
>>> + if (!range_lock_is_reader(blocked_lock)) {
>>> + ret = false;
>>> + goto unlock;
>>> + }
>>> + }
>>> +insert:
>>> + range_lock_set_reader(lock);
>>
>> Here, the lock->waiter field should have been set to current before
>> calling range_lock_set_reader()
>
> But this is a trylock attempt, there is no waiting going on.

Agreed, this one is useless.

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