Re: [PATCH v2] Introduce a description of a new optional tag for Backports

[George Dunlap <George.Dunlap@xxxxxxxxxx>]

> On Apr 15, 2020, at 10:49 AM, Julien Grall <julien@xxxxxxx> wrote:
> 
> 
> 
> On 15/04/2020 10:43, George Dunlap wrote:
>>> On Apr 15, 2020, at 7:23 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>> 
>>> On 14.04.2020 18:54, Stefano Stabellini wrote:
>>>> On Tue, 14 Apr 2020, Jan Beulich wrote:
>>>>> On 10.04.2020 18:49, Stefano Stabellini wrote:
>>>> 
>> [snip]
>>>>>> +    Backport: all
>>>>>> +
>>>>>> +It marks a commit for being a candidate for backports to all relevant
>>>>>> +trees.
>>>>> 
>>>>> I'm unconvinced of the utility of this form - what "all" resolves to
>>>>> changes over time. There's almost always a first version where a
>>>>> particular issue was introduced. If we want this to be generally
>>>>> useful, imo we shouldn't limit the scope of the tag to the upstream
>>>>> maintained stable trees.
>>>> 
>>>> The reason why I suggested also to have a "wildcard" version of this
>>>> tag, is that the person adding the tag (could be the contributor trying
>>>> to be helpful) might not know exactly to which stable trees the patch
>>>> should be backported to.
>>>> 
>>>> Writing this sentence, I realize that I really meant "any" rather than
>>>> "all". Would you prefer if I used "any"? Or we could even suggest to leave
>>>> it black like this:
>>>> 
>>>>  Backport:
>>>> 
>>>> But it looks a bit weird.
>>> 
>>> Indeed. Instead of "all" or "any", how about "yes", "unspecified", or
>>> "unknown"? Nevertheless, I still think people asking for a backport
>>> should be nudged towards determining the applicable range; them not
>>> doing so effectively pushes the burden to the general maintainers or
>>> the stable tree ones, both of which scales less well. Omitting the
>>> tag if they don't want to invest the time would to me then seem to
>>> be the cleanest alternative. Albeit I'm sure views here will vary.
>> FWIW asking people adding the tag to do the work of figuring out which 
>> versions to backport to makes sense to me.
> 
> If you ask the contributor to do the work then you need to give guidance on 
> the "older" version you can specify in Backport.
> 
> For instance, let say the bug was introduced in Xen 4.2. Are we allowing the 
> user to specify Backport: 4.2+ or should it be 4.11+?
> 
> I would favor the former as this helps for downstream user which haven't yet 
> moved to the supported stable tree.

I agree that specifying the oldest revision possible would be helpful.

However, I don’t think finding the absolute oldest revision should be 
*required* — imagine a bug that was introduced between 3.2 and 3.3.  It’s also 
perfectly fine if you go all the way back to 4.2 and stop because you get 
bored, not because you found out that 4.1 didn’t need it.

On the other hand, contributors should be expected to find out if it needs to 
be backported *at least* to fully-supported releases.

I think whatever text we come up with should probably say that contributors are 
“expected” (or “required”) to specify which currently-supported releases need 
the backport;  but “encouraged” to specify a release as far back as possible.

 -George