Minutes for 0319: Race condition in 802.1Q-2018 between List Config state machine (clause 8.6.9.3) and Cycle Timer state machine (clause 8.6.9.1)

Standard: IEEE Std. 802.1Q-2018 Clause: 8.6.9.3 Draft with fix: Q-Rev/D?.? Submitted: 2021-04-15
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Date Meeting Text Status
2021-06-01 Jun 2021 Concall The request as briefly reviewed and it was agreed to requestor to attend the next maintenance call to further explain the request. At first glance others did not see or understand the described race condition. Technical experts review
2021-06-08 8 Jun 2021 Concall A contribution describing the issue further is available at: https://www.ieee802.org/1/files/public/docs2021/maint-regev-scheduled-traffic-race-condition-0421-v02.pdf. It was agreed that there are issues with the state machines that need to be addressed. One suggestion was to break apart the SET_CYCLE_START_TIME state in the 8.6.9.1 Cycle Timer state machine into new states for each of the conditions described in the SetCycleStartTime() procedure. Then an explicit (non-UTC) transition into those states could be identified. It was also pointed out that Figure 8-18, which shows the high-level relationship between state machines in this area of the document is incomplete. The 8.6.9.3 List Config state machine is not shown in this figure and it is precisely the variables used to interlock this machine with the Cycle Timer state machine that is creating the issue. So, Figure 8-18 must also be updated. A final suggestion was made that text should be included that describes the expectations and assumptions about timing delays in reacting to events that trigger state machine transitions. It was agreed to continue discussing the issue and a future contribution will be created to reflect the current ideas discussed on the issue. Technical experts review
2021-08-11 11 Aug 2021 Concall Another contribution was provided to discuss the issue: https://www.ieee802.org/1/files/public/docs2021/maint-regev-scheduled-traffic-race-condition-0821-v01.pdf. Two solutions are proposed in the contribution. Technical experts review
2021-09-22 20 Sep 2021 Interim The request was presented to the TSN TG during the September Interim using https://www.ieee802.org/1/files/public/docs2021/maint-regev-scheduled-traffic-race-condition-0921-v01.pdf. Solution #1 was agreed by the TG and the requestor will submit a comment against Q-Rev for the initial SA ballot. Complete then Ballot

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