Re: In defense of Link (was Re: [b4] initial "b4 dig" to supplant Link: trailers)

[Sasha Levin <sashal@kernel.org>]

On Mon, Oct 13, 2025 at 02:44:28PM -0700, Linus Torvalds wrote:
>For example, while I think that a "git rebase --keep-merges" workflow
>is a bit scary and opens you up to lots of possible things going
>wrong, having some way for "git rebase -i" to *add* merges
>interactively might be a nice option.
>
>I've personally had the situation where I created some series of
>patches and wanted to group them later. What I would do is then create
>a different branch, rebase the patches I wanted to keep in one series
>in that branch, and then go back, and rebase the original branch with
>the remaining commits.

[...]

>Having a linear series of patches delimited by merges to group them
>and document them would probably work really well, but it would need
>to fit in with all the other tools, and as mentioned, many tools
>really do just do "patch series".

[...]

>So rather than doing a separate branch, rebasing things there, and
>going back and rebasing away the things in my original branch, doing
>just 'git rebase -i" in the original branch and having some way to say
>"this is the start of this series", and a "this is the end of the
>series", and having git rebase create a set of linear series with
>merges that delineate them might be quite convenient.

I'm using such workflow for my backporting work: I often want to group the
patch I'm backporting along with it's dependencies into a single "atomic" unit
to make it easier to review those changes later.

It currently uses hackery like the one you've described. Something like this:

   N=$1
   saved=$(git rev-parse HEAD)
   temp="tmp-triangle-$(date +%s)"

   git branch $temp $saved
   git reset --hard HEAD~$N
   git merge --no-ff -m "${2:-Merge triangle of last $N commits}" $temp
   git branch -D $temp


Which creates a structure such as:

   $ git log -5 --oneline --graph 11faed99eb
   *   11faed99eb030 FAILED: 64e0d839c589 ("mfd: intel_soc_pmic_chtdc_ti: Set use_single_read regmap_config flag")
   |\  
   | * 3bc90aaf9933e mfd: intel_soc_pmic_chtdc_ti: Set use_single_read regmap_config flag
   | * 08b4fd511c7f9 mfd: intel_soc_pmic_chtdc_ti: Drop unneeded assignment for cache_type
   | * f6d0ec2c9ccb4 mfd: intel_soc_pmic_chtdc_ti: Fix invalid regmap-config max_register value
   |/  
   * 2b2cbdcede387 (tag: v6.12.52, stable/linux-6.12.y) Linux 6.12.52


If you want to use it as part of your git-rebase workflow, just call the script during rebase:

   pick c3c4268124d22 # kbuild: Use '--strip-unneeded-symbol' for removing module device table symbols
   pick 4ee16af35eb65 # tracing: Fix tracing_mark_raw_write() to use buf and not ubuf
   pick 88d5c7c180dfc # tracing: Stop fortify-string from warning in tracing_mark_raw_write()
   x stable-make-triangle 2
   pick ed5afe51ba32e # irqchip/aspeed-scu-ic: Fix an IS_ERR() vs NULL check
   pick 89d38b0392fa4 # irqchip/sifive-plic: Avoid interrupt ID 0 handling during suspend/resume
   pick 3897851fae349 # Revert "i2c: boardinfo: Annotate code used in init phase only"
   pick 49a451202c681 # Linux 6.18-rc1


Which results in something like what you were looking for?

   $ git log --oneline --graph -10
   * 53cb9bf28b1b7 (HEAD) Linux 6.18-rc1
   * d6f9a71712aff Revert "i2c: boardinfo: Annotate code used in init phase only"
   * 8943a4934a860 irqchip/sifive-plic: Avoid interrupt ID 0 handling during suspend/resume
   * 12257b8fccebf irqchip/aspeed-scu-ic: Fix an IS_ERR() vs NULL check
   *   decf0198935a6 Merge triangle of last 2 commits
   |\  
   | * 88d5c7c180dfc tracing: Stop fortify-string from warning in tracing_mark_raw_write()
   | * 4ee16af35eb65 tracing: Fix tracing_mark_raw_write() to use buf and not ubuf
   |/  
   * c3c4268124d22 kbuild: Use '--strip-unneeded-symbol' for removing module device table symbols
   * 0f43fbd0b759c s390/vmlinux.lds.S: Move .vmlinux.info to end of allocatable sections

-- 
Thanks,
Sasha