linux/Documentation/stable_kernel_rules.txt
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   1.. _stable_kernel_rules:
   2
   3Everything you ever wanted to know about Linux -stable releases
   4===============================================================
   5
   6Rules on what kind of patches are accepted, and which ones are not, into the
   7"-stable" tree:
   8
   9 - It must be obviously correct and tested.
  10 - It cannot be bigger than 100 lines, with context.
  11 - It must fix only one thing.
  12 - It must fix a real bug that bothers people (not a, "This could be a
  13   problem..." type thing).
  14 - It must fix a problem that causes a build error (but not for things
  15   marked CONFIG_BROKEN), an oops, a hang, data corruption, a real
  16   security issue, or some "oh, that's not good" issue.  In short, something
  17   critical.
  18 - Serious issues as reported by a user of a distribution kernel may also
  19   be considered if they fix a notable performance or interactivity issue.
  20   As these fixes are not as obvious and have a higher risk of a subtle
  21   regression they should only be submitted by a distribution kernel
  22   maintainer and include an addendum linking to a bugzilla entry if it
  23   exists and additional information on the user-visible impact.
  24 - New device IDs and quirks are also accepted.
  25 - No "theoretical race condition" issues, unless an explanation of how the
  26   race can be exploited is also provided.
  27 - It cannot contain any "trivial" fixes in it (spelling changes,
  28   whitespace cleanups, etc).
  29 - It must follow the
  30   :ref:`Documentation/SubmittingPatches <submittingpatches>`
  31   rules.
  32 - It or an equivalent fix must already exist in Linus' tree (upstream).
  33
  34
  35Procedure for submitting patches to the -stable tree
  36----------------------------------------------------
  37
  38 - If the patch covers files in net/ or drivers/net please follow netdev stable
  39   submission guidelines as described in
  40   Documentation/networking/netdev-FAQ.txt
  41 - Security patches should not be handled (solely) by the -stable review
  42   process but should follow the procedures in
  43   :ref:`Documentation/SecurityBugs <securitybugs>`.
  44
  45For all other submissions, choose one of the following procedures
  46-----------------------------------------------------------------
  47
  48.. _option_1:
  49
  50Option 1
  51********
  52
  53To have the patch automatically included in the stable tree, add the tag
  54
  55.. code-block:: none
  56
  57     Cc: stable@vger.kernel.org
  58
  59in the sign-off area. Once the patch is merged it will be applied to
  60the stable tree without anything else needing to be done by the author
  61or subsystem maintainer.
  62
  63.. _option_2:
  64
  65Option 2
  66********
  67
  68After the patch has been merged to Linus' tree, send an email to
  69stable@vger.kernel.org containing the subject of the patch, the commit ID,
  70why you think it should be applied, and what kernel version you wish it to
  71be applied to.
  72
  73.. _option_3:
  74
  75Option 3
  76********
  77
  78Send the patch, after verifying that it follows the above rules, to
  79stable@vger.kernel.org.  You must note the upstream commit ID in the
  80changelog of your submission, as well as the kernel version you wish
  81it to be applied to.
  82
  83:ref:`option_1` is **strongly** preferred, is the easiest and most common.
  84:ref:`option_2` and :ref:`option_3` are more useful if the patch isn't deemed
  85worthy at the time it is applied to a public git tree (for instance, because
  86it deserves more regression testing first).  :ref:`option_3` is especially
  87useful if the patch needs some special handling to apply to an older kernel
  88(e.g., if API's have changed in the meantime).
  89
  90Note that for :ref:`option_3`, if the patch deviates from the original
  91upstream patch (for example because it had to be backported) this must be very
  92clearly documented and justified in the patch description.
  93
  94The upstream commit ID must be specified with a separate line above the commit
  95text, like this:
  96
  97.. code-block:: none
  98
  99    commit <sha1> upstream.
 100
 101Additionally, some patches submitted via Option 1 may have additional patch
 102prerequisites which can be cherry-picked. This can be specified in the following
 103format in the sign-off area:
 104
 105.. code-block:: none
 106
 107     Cc: <stable@vger.kernel.org> # 3.3.x: a1f84a3: sched: Check for idle
 108     Cc: <stable@vger.kernel.org> # 3.3.x: 1b9508f: sched: Rate-limit newidle
 109     Cc: <stable@vger.kernel.org> # 3.3.x: fd21073: sched: Fix affinity logic
 110     Cc: <stable@vger.kernel.org> # 3.3.x
 111     Signed-off-by: Ingo Molnar <mingo@elte.hu>
 112
 113The tag sequence has the meaning of:
 114
 115.. code-block:: none
 116
 117     git cherry-pick a1f84a3
 118     git cherry-pick 1b9508f
 119     git cherry-pick fd21073
 120     git cherry-pick <this commit>
 121
 122Also, some patches may have kernel version prerequisites.  This can be
 123specified in the following format in the sign-off area:
 124
 125.. code-block:: none
 126
 127     Cc: <stable@vger.kernel.org> # 3.3.x-
 128
 129The tag has the meaning of:
 130
 131.. code-block:: none
 132
 133     git cherry-pick <this commit>
 134
 135For each "-stable" tree starting with the specified version.
 136
 137Following the submission:
 138
 139 - The sender will receive an ACK when the patch has been accepted into the
 140   queue, or a NAK if the patch is rejected.  This response might take a few
 141   days, according to the developer's schedules.
 142 - If accepted, the patch will be added to the -stable queue, for review by
 143   other developers and by the relevant subsystem maintainer.
 144
 145
 146Review cycle
 147------------
 148
 149 - When the -stable maintainers decide for a review cycle, the patches will be
 150   sent to the review committee, and the maintainer of the affected area of
 151   the patch (unless the submitter is the maintainer of the area) and CC: to
 152   the linux-kernel mailing list.
 153 - The review committee has 48 hours in which to ACK or NAK the patch.
 154 - If the patch is rejected by a member of the committee, or linux-kernel
 155   members object to the patch, bringing up issues that the maintainers and
 156   members did not realize, the patch will be dropped from the queue.
 157 - At the end of the review cycle, the ACKed patches will be added to the
 158   latest -stable release, and a new -stable release will happen.
 159 - Security patches will be accepted into the -stable tree directly from the
 160   security kernel team, and not go through the normal review cycle.
 161   Contact the kernel security team for more details on this procedure.
 162
 163Trees
 164-----
 165
 166 - The queues of patches, for both completed versions and in progress
 167   versions can be found at:
 168
 169        http://git.kernel.org/?p=linux/kernel/git/stable/stable-queue.git
 170
 171 - The finalized and tagged releases of all stable kernels can be found
 172   in separate branches per version at:
 173
 174        http://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git
 175
 176
 177Review committee
 178----------------
 179
 180 - This is made up of a number of kernel developers who have volunteered for
 181   this task, and a few that haven't.
 182