Re: [Ksummit-discuss] [CORE TOPIC] stable workflow

[Vinod Koul <vinod.koul@intel.com>]

On Mon, Jul 11, 2016 at 01:13:35AM -0400, Theodore Ts'o wrote:
> On Mon, Jul 11, 2016 at 10:30:00AM +0530, Vinod Koul wrote:
> > > There are **eleven** stable or longterm trees listed on kernel.org.
> > > If you are going to ask patch submitters to test on all of the stable
> > > trees, that pretty much guarantees that nothing at all will be cc'ed
> > > to stable.
> > 
> > Isn't that a part of problem as well. If I am submitting a fix,
> > shouldn't I be able to backport and validate the fix on stable kernels?
> 
> You might be *able* to pay me a $1000 dollars (e.g., you have that
> much in your savings account).  That doesn't mean that you *will*, or
> that you *should*, or have any moral *obligation* to pay me $1000
> dollars.  (But if you do want to write me a check, feel free....  :-)
> 
> If a developer at Facebook finds a bug, and they fix it for upstream,
> they do so partially out of the goodness of their hearts, and
> partially because that way they don't have to do extra work to forward
> port a private patch when they move to a newer upstream kernel.  But
> the GPL doesn't require that they share bug fixes with upstream ---
> it's just in their economic incentive to do so.  (Even if it does help
> their competitors who might now not have to do the same bug report.
> And since developers at Google are also doing the same thing, it all
> works well.)
> 
> Ok, now let's grant that the same Facebook developer is *able* to
> backport the same patch to 11 different stable kernels, and do a full
> QA validation on all of these different stable.  Now the extra 15-30
> minutes that it might take to prepare the patch for upstream might now
> take a day or two.  What benefit does the Facebook developer have
> doing that?  Almost none.  By what moral or legal right do you have to
> demand that the Facebook developer do all of that extra work?  Exactly
> zero.
> 
> Now, suppose *you* are under a tight deadline to get work done for
> your company's shipping product.  How do you think your manager would
> react if you tell her, I'm sorry, but our competitors at Qualcomm are
> demanding that I take my upstream patch contribution and backport and
> QA it on a dozen different stable kernels so they can more easily put
> out BSP kernels for products that directly complete with Intel's?  Let
> me guess that the answer might very well be, "not well".

Ted,

I do whole heartedly agree to your arguments and yes that is a big
issue. *BUT* what is the solution then, Maintainers do not even have
hardware to test.

> > > And if device kernels or BSP kernels aren't bothering to track
> > > -stable, it becomes even more unfair to force that work on the
> > > maintainers or patch submitters.  If they are just going to be cherry
> > > picking random patches out of the -stable kernel when they notice a
> > > problem, does it make sense to do invest in doing full QA's for every
> > > single commit before it goes into -stable?
> > 
> > And IMO since submitter know the target and has the hardware for test,
> > it would be more easy for that person to verify..
> 
> The submitter is not necessarily going to have all of the hardware to
> test.  Heck, Intel has shipped i915 drivers that have broken my
> Thinkpad dock (in fact the video out on my dock has been mostly
> useless for the past year), multiple times in the past and so I'm
> pretty sure Intel isn't testing their i915 driver on all of the
> different hardware connected to the i915 chipset --- and this is
> regressions on the *HEAD* of the Linux tree, never mind backports into
> stable....

But the person might be slightly better off than you or me :-)

-- 
~Vinod