netdev - Re: [PATCH net-next 2/4] selftests: tc-testing: rework namespaces and devices setup

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Message-ID: <20231116141129.GB109951@vergenet.net>
Date: Thu, 16 Nov 2023 14:11:29 +0000
From: Simon Horman <horms@...nel.org>
To: Pedro Tammela <pctammela@...atatu.com>
Cc: netdev@...r.kernel.org, jhs@...atatu.com, xiyou.wangcong@...il.com,
	jiri@...nulli.us, davem@...emloft.net, edumazet@...gle.com,
	kuba@...nel.org, pabeni@...hat.com, shuah@...nel.org,
	victor@...atatu.com
Subject: Re: [PATCH net-next 2/4] selftests: tc-testing: rework namespaces
 and devices setup

On Tue, Nov 14, 2023 at 01:04:40PM -0300, Pedro Tammela wrote:
> As mentioned in the TC Workshop 0x17, our recent changes to tdc broke
> downstream CI systems like tuxsuite. The issue is the classic problem
> with rcu/workqueue objects where you can miss them if not enough wall time
> has passed. The latter is subjective to the system and kernel config,
> in my machine could be nanoseconds while in another could be microseconds
> or more.
> 
> In order to make the suite deterministic, poll for the existence
> of the objects in a reasonable manner. Talking netlink directly is the
> the best solution in order to avoid paying the cost of multiple
> 'fork()' calls, so introduce a netlink based setup routine using
> pyroute2. We leave the iproute2 one as a fallback when pyroute2 is not
> available.
> 
> Also rework the iproute2 side to mimic the netlink routine where it
> creates DEV0 as the peer of DEV1 and moves DEV1 into the net namespace.
> This way when the namespace is deleted DEV0 is also deleted
> automatically, leaving no margin for resource leaks.
> 
> Another bonus of this change is that our setup time sped up by a factor
> of 2 when using netlink.
> 
> Signed-off-by: Pedro Tammela <pctammela@...atatu.com>

Reviewed-by: Simon Horman <horms@...nel.org>