[LEDE-DEV] [PATCH] ubus cli: wait_for: fix race causing false timeouts

[Zefir Kurtisi]

On 10/07/2016 02:15 PM, Alexandru Ardelean wrote:
> On Fri, Oct 7, 2016 at 3:09 PM, Felix Fietkau <nbd at nbd.name> wrote:
>> Instead of introducing yet another timer, wouldn't it also be possible
>> to close this race window by registering the event handler before
>> attempting the lookup?
>>
>> - Felix
>>
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> 
> I've also seen this race.
> I tried something like this:
> https://github.com/commodo/ubus/commit/8c3986caaa7cd2c12f2b8907ceea54c5bdce3bd2
> 
> But never got around to doing much testing to see if the race goes
> away completely.
> So, I never pushed it upstream.
> 
> @Zefir, maybe you could try it ?
> 
> Thanks
> Alex
> 
Hi Alex,

your assumption is right, that's the root cause for the random timeouts.

Unfortunately, it is hard to provide a positive proof, since for me the effect
went away when I added some logging in between.

My patch made it disappear, but of course what Felix suggests and you already
implemented is the better approach. I'll take your commit instead and test it.
>From looking at the changes it should do, but to get some confidence it will take
some time.


Cheers,
Zefir