On Fri, Jul 15, 2016 at 05:26:40AM +0800, Wanpeng Li wrote: > 2016-07-14 22:52 GMT+08:00 Waiman Long <[email protected]>: > [...] > > 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. > */
So I'm not sure. Yes it was a bug, but its fairly 'obvious' it should be vcpu_hashed, we did after all hash the thing. > Btw, do you think patch title should be improved, what do you like? I changed it to: "locking/pvqspinlock: Fix double hash race"
