Re: [dpdk-dev] [PATCH] eal: register rte_panic user callback

[Thomas Monjalon <thomas@monjalon.net>]

07/03/2018 10:05, Burakov, Anatoly:
> On 07-Mar-18 8:32 AM, Thomas Monjalon wrote:
> > Hi,
> > 
> > 06/03/2018 19:28, Arnon Warshavsky:
> >> The use case addressed here is dpdk environment init
> >> aborting the process due to panic,
> >> preventing the calling process from running its own tear-down actions.
> > 
> > Thank you for working on this long standing issue.
> > 
> >> A preferred, though ABI breaking solution would be
> >> to have the environment init always return a value
> >> rather than abort upon distress.
> > 
> > Yes, it is the preferred solution.
> > We should not use exit (panic & co) inside a library.
> > It is important enough to break the API.
> 
> +1, panic exists mostly for historical reasons AFAIK. it's a pity i 
> didn't think of it at the time of submitting the memory hotplug RFC, 
> because i now hit the same issue with the v1 - we might panic while 
> holding a lock, and didn't realize that it was an API break to change 
> this behavior.
> 
> Can this really go into current release without deprecation notices?

If such an exception is done, it must be approved by the technical board.
We need to check few criterias:
	- which functions need to be changed
	- how the application is impacted
	- what is the urgency

If a panic is removed and the application is not already checking some
error code, the execution will continue without considering the error.

Some rte_panic could be probably removed without any impact on applications.
Some rte_panic could wait for 18.08 with a notice in 18.05.
If some rte_panic cannot wait, it must be discussed specifically.