Hello Willy,
On Sat, 20 Mar 2021 at 10:09, Willy Tarreau <w...@1wt.eu> wrote:
> > 1.6 was EOL last year, I don't understand why there is a last release.
>
> There were some demands late last year and early this year to issue a
> last one with pending fixes to "flush the pipe" but it was terribly
> difficult to find enough time to go through the whole chain with the
> other nasty bugs that kept us busy.
>
> > Both 1.6 and 1.7 are marked for critical fixes but many fixes are pushed
> > in it. The risk is to introduce a late regression in this last version.
>
> There's always such a risk when doing backports unfortunately and it's
> always difficult to set the boundary between what is needed and what
> not. A lot of the issues I'm seeing there are crash-related, and
> others address not-so-funny recent changes in compilers behaviors
> leading to bad code generation. There are also some that were possibly
> not strictly necessary, but then they're obvious fixes (like the one
> on the timer that's incorrectly compared), and whose possible
> consequences are not always trivial to imagine (such as checks looping
> at 100% CPU every 24 days maybe depending on the tick's sign).
I agree that finding the sweet spot can be difficult, but I have to
say I share Vincent's concerns. I do feel like currently we backport
*a lot*, especially on those near-EOLed trees. When looking at the
list of backported patches, I don't feel like the age and remaining
lifetime is taken into consideration.
I don't want to be the monday morning quarterback, but in 1.7 we have
853926a9ac ("BUG/MEDIUM: ebtree: use a byte-per-byte memcmp() to
compare memory blocks") and I quote from the commit message:
> This is not correct and definitely confuses address sanitizers. In real
> life the problem doesn't have visible consequences.
> [...]
> there is no way such a multi-byte access will cross a page boundary
> and end up reading from an unallocated zone. This is why it was
> never noticed before.
This sounds like a backport candidate for "warm" stable branches
(maybe), but 1.7 and 1.8 feel too "cold" for this, even 8 - 9 months
ago.
This backport specifically causes a build failure of 1.7.13 on musl
(#760) - because of a missing backport, but that's just an example. 39
"MINOR" patches made it into 1.6.16, 62 patches in 1.7.13. While it is
true that a lot of "MINOR" tagged patches are actually important, this
is still a large number for a tree that is supposed to die so soon.
Very rarely do users build from source from such old trees anyway (and
those users would be especially conservative, definitely not
interested in generic, non-important improvements).
> But with this in mind, there were two options:
> - not releasing the latest fixes
You are talking about whether to publish a release or not for tree
X.Y, with the backports that are already in the tree. I don't think
that's the issue.
I think the discussion should be about what commits land in those old
trees in the first place. And I don't believe it is scalable to make
those decisions during your backporting sessions. Instead I believe we
should be more conservative when suggesting backports in the commit
message. Currently, we say "should/can be backported to X.Y" based on
whether it is *technically* possible to do so for supported trees, not
if it makes sense considering the age and lifetime of the suggested
tree. This is why I'm proposing a commit author should make such
considerations when suggesting backports. Avoiding backports to cold
trees of no-impact improvements and minor fixes for rare corner cases
should be a goal.
Unless we insist every single bug needs to be fixed on every single
supported release branch.
lukas
