Re: [PATCH net-next 4/6] ionic: add queue lock around open and stop

On 8/27/21 5:39 PM, Jakub Kicinski wrote:

On Fri, 27 Aug 2021 11:55:10 -0700 Shannon Nelson wrote:

quoted

Add the queue configuration lock to ionic_open() and
ionic_stop() so that they don't collide with other in parallel
queue configuration actions such as MTU changes as can be
demonstrated with a tight loop of ifup/change-mtu/ifdown.

Say more? how are up/down/change mtu not under rtnl_lock?

Sorry, that commit message didn't get updated as it should have. The MTU change played with the timing of actions just right, but wasn't the culprit.  The actual issue was that the watchdog and the ionic_stop collided: ionic_stop had started taking the queues down but without grabbing the mutex, and the watchdog timer went off and ran the link_check which grabbed the mutex and tried to bring them back up again.  This didn't break anything in the driver, but confused the NIC firmware and left the interface non-operational. This was cleared with another ifdown/ifup cycle.

I can repost with a better commit description.

sln