On 09/23/2015 08:23 PM, Ming Lei wrote:
IMO, mq_freeze_depth should only be accessed in slow path, and looks
the race just happens during the small window between increasing
'mq_freeze_depth' and killing the percpu counter.
Hello Ming,
My concern is that *not* checking mq_freeze_depth in the hot path can
cause a livelock. If there is a software layer, e.g. multipathd, that
periodically submits new commands and if these commands take time to
process e.g. because the transport layer is unavailable, how to
guarantee that freezing ever succeeds without checking mq_freeze_depth
in the hot path ?
Thanks,
Bart.
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