pull-requests.rst (7880B)
1.. _pullrequests: 2 3Creating Pull Requests 4====================== 5 6This chapter describes how maintainers can create and submit pull requests 7to other maintainers. This is useful for transferring changes from one 8maintainers tree to another maintainers tree. 9 10This document was written by Tobin C. Harding (who at that time, was not an 11experienced maintainer) primarily from comments made by Greg Kroah-Hartman 12and Linus Torvalds on LKML. Suggestions and fixes by Jonathan Corbet and 13Mauro Carvalho Chehab. Misrepresentation was unintentional but inevitable, 14please direct abuse to Tobin C. Harding <me@tobin.cc>. 15 16Original email thread:: 17 18 https://lore.kernel.org/r/20171114110500.GA21175@kroah.com 19 20 21Create Branch 22------------- 23 24To start with you will need to have all the changes you wish to include in 25the pull request on a separate branch. Typically you will base this branch 26off of a branch in the developers tree whom you intend to send the pull 27request to. 28 29In order to create the pull request you must first tag the branch that you 30have just created. It is recommended that you choose a meaningful tag name, 31in a way that you and others can understand, even after some time. A good 32practice is to include in the name an indicator of the subsystem of origin 33and the target kernel version. 34 35Greg offers the following. A pull request with miscellaneous stuff for 36drivers/char, to be applied at the Kernel version 4.15-rc1 could be named 37as ``char-misc-4.15-rc1``. If such tag would be produced from a branch 38named ``char-misc-next``, you would be using the following command:: 39 40 git tag -s char-misc-4.15-rc1 char-misc-next 41 42that will create a signed tag called ``char-misc-4.15-rc1`` based on the 43last commit in the ``char-misc-next`` branch, and sign it with your gpg key 44(see :ref:`Documentation/maintainer/configure-git.rst <configuregit>`). 45 46Linus will only accept pull requests based on a signed tag. Other 47maintainers may differ. 48 49When you run the above command ``git`` will drop you into an editor and ask 50you to describe the tag. In this case, you are describing a pull request, 51so outline what is contained here, why it should be merged, and what, if 52any, testing has been done. All of this information will end up in the tag 53itself, and then in the merge commit that the maintainer makes if/when they 54merge the pull request. So write it up well, as it will be in the kernel 55tree for forever. 56 57As said by Linus:: 58 59 Anyway, at least to me, the important part is the *message*. I want 60 to understand what I'm pulling, and why I should pull it. I also 61 want to use that message as the message for the merge, so it should 62 not just make sense to me, but make sense as a historical record 63 too. 64 65 Note that if there is something odd about the pull request, that 66 should very much be in the explanation. If you're touching files 67 that you don't maintain, explain _why_. I will see it in the 68 diffstat anyway, and if you didn't mention it, I'll just be extra 69 suspicious. And when you send me new stuff after the merge window 70 (or even bug-fixes, but ones that look scary), explain not just 71 what they do and why they do it, but explain the _timing_. What 72 happened that this didn't go through the merge window.. 73 74 I will take both what you write in the email pull request _and_ in 75 the signed tag, so depending on your workflow, you can either 76 describe your work in the signed tag (which will also automatically 77 make it into the pull request email), or you can make the signed 78 tag just a placeholder with nothing interesting in it, and describe 79 the work later when you actually send me the pull request. 80 81 And yes, I will edit the message. Partly because I tend to do just 82 trivial formatting (the whole indentation and quoting etc), but 83 partly because part of the message may make sense for me at pull 84 time (describing the conflicts and your personal issues for sending 85 it right now), but may not make sense in the context of a merge 86 commit message, so I will try to make it all make sense. I will 87 also fix any speeling mistaeks and bad grammar I notice, 88 particularly for non-native speakers (but also for native ones 89 ;^). But I may miss some, or even add some. 90 91 Linus 92 93Greg gives, as an example pull request:: 94 95 Char/Misc patches for 4.15-rc1 96 97 Here is the big char/misc patch set for the 4.15-rc1 merge window. 98 Contained in here is the normal set of new functions added to all 99 of these crazy drivers, as well as the following brand new 100 subsystems: 101 - time_travel_controller: Finally a set of drivers for the 102 latest time travel bus architecture that provides i/o to 103 the CPU before it asked for it, allowing uninterrupted 104 processing 105 - relativity_shifters: due to the affect that the 106 time_travel_controllers have on the overall system, there 107 was a need for a new set of relativity shifter drivers to 108 accommodate the newly formed black holes that would 109 threaten to suck CPUs into them. This subsystem handles 110 this in a way to successfully neutralize the problems. 111 There is a Kconfig option to force these to be enabled 112 when needed, so problems should not occur. 113 114 All of these patches have been successfully tested in the latest 115 linux-next releases, and the original problems that it found have 116 all been resolved (apologies to anyone living near Canberra for the 117 lack of the Kconfig options in the earlier versions of the 118 linux-next tree creations.) 119 120 Signed-off-by: Your-name-here <your_email@domain> 121 122 123The tag message format is just like a git commit id. One line at the top 124for a "summary subject" and be sure to sign-off at the bottom. 125 126Now that you have a local signed tag, you need to push it up to where it 127can be retrieved:: 128 129 git push origin char-misc-4.15-rc1 130 131 132Create Pull Request 133------------------- 134 135The last thing to do is create the pull request message. ``git`` handily 136will do this for you with the ``git request-pull`` command, but it needs a 137bit of help determining what you want to pull, and on what to base the pull 138against (to show the correct changes to be pulled and the diffstat). The 139following command(s) will generate a pull request:: 140 141 git request-pull master git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git/ char-misc-4.15-rc1 142 143Quoting Greg:: 144 145 This is asking git to compare the difference from the 146 'char-misc-4.15-rc1' tag location, to the head of the 'master' 147 branch (which in my case points to the last location in Linus's 148 tree that I diverged from, usually a -rc release) and to use the 149 git:// protocol to pull from. If you wish to use https://, that 150 can be used here instead as well (but note that some people behind 151 firewalls will have problems with https git pulls). 152 153 If the char-misc-4.15-rc1 tag is not present in the repo that I am 154 asking to be pulled from, git will complain saying it is not there, 155 a handy way to remember to actually push it to a public location. 156 157 The output of 'git request-pull' will contain the location of the 158 git tree and specific tag to pull from, and the full text 159 description of that tag (which is why you need to provide good 160 information in that tag). It will also create a diffstat of the 161 pull request, and a shortlog of the individual commits that the 162 pull request will provide. 163 164Linus responded that he tends to prefer the ``git://`` protocol. Other 165maintainers may have different preferences. Also, note that if you are 166creating pull requests without a signed tag then ``https://`` may be a 167better choice. Please see the original thread for the full discussion. 168 169 170Submit Pull Request 171------------------- 172 173A pull request is submitted in the same way as an ordinary patch. Send as 174inline email to the maintainer and CC LKML and any sub-system specific 175lists if required. Pull requests to Linus typically have a subject line 176something like:: 177 178 [GIT PULL] <subsystem> changes for v4.15-rc1