This was actually done with a Coccinelle patch after finding plain
free() calls out of tree:

    $ cat >free_obj.cocci <<EOF
    @@
    expression obj, objp, magic;
    @@

    (
    TAKE_OBJ_NOTNULL(obj, objp, magic);
    |
    CAST_OBJ_NOTNULL(obj, objp, magic);
    |
    CHECK_OBJ_NOTNULL(obj, magic);
    |
    CHECK_OBJ_ORNULL(obj, magic);
    |
    CHECK_OBJ(obj, magic);
    )
    ...
    - free(obj);
    + FREE_OBJ(obj);
    $ spatch --dir . --in-place --sp-file free_obj.cocci

Asking again, could we consider keeping Coccinelle patches around?

Submitted by:	@tnn2

Fixes #2954

Fixes #2953

on ppc64 fedora, the thread_pool_stack minimum is 128kb due to
sysconf(_SC_THREAD_STACK_MIN) = 131072

It does not harm the test to use a larger stacksize, so we adjust it to
this requirement for consistency and simplicity

It is now safe to assume that a constructor is always called with proper
values or never called to begin with, and as such to panic if it's not
the case.

Bonus polish in the files I visited.

Refs #2297

not even in vmod_debug because it sets the only catflap example for the
time being.

Happy new year!

This reverts commit de3e581e.

tests/saintmode/test04.vtc from varnish-modules revealed that there may
be use cases where it is implied that vcl_backend_error will leave a
ttl=0 object and the sale object will remain in place.

This can be resolved by:

	- return(abandon) for these cases or
	- making the HSH_Kill conditional on bo->fetch_objcore->ttl > 0

but I already has concerns regarding the impact of this change and have
them even more now.

We need time to ponder about the consequences and a documented
inefficiency is better than unexpected behaviour in a release.

Our stack space canary in v00004.vtc fell off the twig on fedora rawhide
i686

Thank you to @ingvarha for testing, reporting and all your support
overall!

Fixes #2946 in the sense that we want to treat backend synth like any
other object and kill the stale object it replaces.

The two HSH_Kill calls could also be subsumed in vbf_fetch_thread(),
but after an irc discussion, phk decided that he wanted to aim for even
more consolidation later.

The test checks that we remove the stale_oc, but not when abandoning the
bereq.

I'm keeping that information in both the changes and upgrading documents
to increase the chances that people will notice it.

The imprecise "changes" statement predated the decision to drop Python 2
entirely and was spotted by Geoff.

Reported by coverity.

Unless we think of something else to add, this version of the docs
is suitable for the 6.2 release.