Re: [PATCH v3] locking/pvqspinlock: restore/set vcpu_hashed state after failing adaptive locking spinning

[Wanpeng Li]

2016-07-14 22:52 GMT+08:00 Waiman Long <waiman.long@xxxxxxx>:
[...]
> As pv_kick_node() is called immediately after designating the next node as
> the queue head, the chance of this racing is possible, but is not likely
> unless the lock holder vCPU gets preempted for a long time at that right
> moment. This change does not do any harm though, so I am OK with that.
> However, I do want you to add a comment about the possible race in the code
> as it isn't that obvious or likely.

How about something like:

/*
 * If the lock holder vCPU gets preempted for a long time, pv_kick_node will
 * advance its state and hash the lock, restore/set the vcpu_hashed state to
 * avoid the race.
 */

Btw, do you think patch title should be improved, what do you like?

Regards,
Wanpeng Li