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