question about one of your ubuntu patch

[David Lee]

Hi Thadeu,

I just found a patch in
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1857158, "rtc: disable
uie before setting time and enable after"--7e7c005b4b1f1f169bcc. It's
in v4.19.89. But it's not patched in Ubuntu-4.15.0-76.86,which is issued at
Jan 17 2020.
Ubuntu-4.15.0-76.86 contains the commit in the "Fixes:"
in 7e7c005b4b1f1f169bcc, which means that ubuntu introduces the bug. It's
necessary to be patched. And the patch is also in the list of
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1857158. I thought all
the patches
in that website are to be added in ubuntu. Why is not it added in ubuntu?
Is there any other rules?

Thanks

On Wed, Aug 12, 2020 at 9:42 PM David Lee <saynice111 at gmail.com> wrote:

> Hi Thadeu,
>
> we have Kamal do the
> great job of tracking commits to 4.14 and 4.19 and make pull requests so
> those
> can be included in Ubuntu's kernel.
>
> I just measured that there are 13007 commits from 4.15.18 which is
> end-of-life in 4.15 stable branch to a specific ubuntu-bionic
> version, Ubuntu-4.15.0-76.86. 9830 commits in 13007 also exist in 4.14 lts.
> But there is 0 commit which exist in 4.19 lts. Is there anything wrong?
> Can you give me more guidance on this?
> Thanks
>
>
> On Tue, Aug 11, 2020 at 12:49 PM David Lee <saynice111 at gmail.com> wrote:
>
>> Hi,
>>
>> Thanks for your reply. Very helpful to me.
>>
>> There is no upstream Linux 4.15 stable branch.
>>
>> There is no upstream linux 4.15 long term support branch. But there is a
>> Linux stable branch
>> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/log/?h=linux-4.15.y
>> .
>>
>> Ubuntu's bionic is based on Linux 4.15. But there is also linux
>> 4.15-linux 4.15.18 branch in ubuntu-bionic. And commits in Linux
>> 4.15-4.15.18 in ubuntu git is the same as it in Linux git except some
>> ubuntu sauce patches.
>>
>> Besides, how does ubuntu know if there is a new patch added in upstream?
>> And how do ubuntu determine if a patch is necessary for ubuntu?
>> Thanks
>>
>> On Tue, Aug 11, 2020 at 4:32 AM Thadeu Lima de Souza Cascardo <
>> cascardo at canonical.com> wrote:
>>
>>> On Tue, Aug 11, 2020 at 12:33:17AM -0700, David Lee wrote:
>>> > Hi,
>>> >
>>> > I saw your email in the patch "serdev: Fix serdev_uevent failure on
>>> ACPI
>>> > enumerated serdev-controllers
>>> 586ca5b1a90b66eb0a2805c9419683e33d1d418b" in
>>> > ubuntu's git repository.
>>> > I am surprised to find that this patch in ubuntu git is committed on
>>> Apr 12
>>> > 10:06:37 2018. But this patch is committed to linux 4.15 stable branch
>>> > on Apr 12 12:31:11 2018.
>>> > In ubuntu git repository, this patch is also in Linux 4.15 stable
>>> branch.
>>> > Why a patch is committed before it's added in Linux 4.15 stable branch?
>>> >
>>> > Thanks
>>>
>>> Hi, David.
>>>
>>> There is no upstream Linux 4.15 stable branch. Upstream kernel.org git
>>> trees
>>> closest to 4.15 are 4.14 and 4.19. Kamal Mostafa, from the Ubuntu Kernel
>>> team
>>> picks up commits from those trees in order to apply them to Ubuntu bionic
>>> kernel tree, which is based on 4.15. As upstream has stopped publishing
>>> updates
>>> to 4.15 and Ubuntu picked up 4.15 for its Bionic release, we have Kamal
>>> do the
>>> great job of tracking commits to 4.14 and 4.19 and make pull requests so
>>> those
>>> can be included in Ubuntu's kernel.
>>>
>>> But patches are also submitted to Ubuntu's kernel through other ways and
>>> for
>>> other reasons, like when they fix specific bugs tracked at launchpad. It
>>> may
>>> happen that such patches match upstream commits that have both landed on
>>> Kamal's tree and directly on Ubuntu's tree.
>>>
>>> And by git's distributed nature, the same patch may be applied on
>>> different
>>> dates, or it may happen that they are rebased or reapplied, causing them
>>> to
>>> have different commit ids, and even different commit dates or commit
>>> authors,
>>> or have had their messages changed because of sign-offs.
>>>
>>> I didn't investigate the specific case you pointed out, but it may be
>>> that with
>>> the explanations above, you may find other differences between those two
>>> commits that might explain what might have happened.
>>>
>>> Regards.
>>> Thadeu Cascardo.
>>>
>>
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