[dm-devel] [PATCH 6/6] multipathd: Remove a busy-waiting loop

[Bart Van Assche]

On 08/17/2016 07:44 AM, Hannes Reinecke wrote:
> On 08/16/2016 10:11 PM, Bart Van Assche wrote:
>> On 08/15/2016 11:31 PM, Hannes Reinecke wrote:
>>> Makes one wonder: what happens to the waitevent threads?
>>> We won't be waiting for them after applying this patch, right?
>>> So why did we ever had this busy loop here?
>>> Ben?
>>>
>>> (And while we're at the subject: can't we drop the waitevent threads
>>> altogether? We're listening to uevents nowadays, so we should be
>>> notified if something happened to the device-mapper tables. Which should
>>> make the waitevent threads unnecessary, right?)
>>
>> Hello Hannes,
>>
>> Maybe this is not what you had in mind, but would you agree with the
>> attached two patches?
>>
> Well, yes, sort of.
> However, it still would mean that the main multipath daemon thread might
> terminate before the event threads have completed, though.
>
> Not sure if it matters, just wanted to bring is up.

Hello Hannes,

I think that for the tur checker the libcheck_free() function should 
wait until the tur thread has finished. multipathd calls 
remove_maps_and_stop_waiters() during shutdown and that function calls 
libcheck_free() for all checkers that were loaded.

Regarding the waiter threads: stop_waiter_thread() is called by 
_remove_map() so the waiter threads are also stopped during multipathd 
shutdown.

Bart.