[PATCHSET v2] Fix DEFER_TASKRUN ring resize flag manipulation

[Jens Axboe <axboe@kernel.dk>]

Hi,

Two patches here:

1) Fix adding local task_work during ring resize. There's a tiny gap
   where a NULL pointer would be used.

2) Same issue exists in the eventfd handling, so apply the same kind of
   fix there.

Thanks to Hao-Yu Yang for the report and initial fix attempt, and Pavel
for a good suggestion on how best to handle this.

Changes since v1:
- Don't clear -rings_rcu during resize, old rings remain valid until
  post RCU synchronize anyway (Pavel)

-- 
Jens Axboe