Documentation/process/stable-kernel-rules.rst - linux - Git at Google

 .. _stable_kernel_rules:

 Everything you ever wanted to know about Linux -stable releases
 ===============================================================

 Rules on what kind of patches are accepted, and which ones are not, into the
 "-stable" tree:

  - It must be obviously correct and tested.
  - It cannot be bigger than 100 lines, with context.
  - It must fix only one thing.
  - It must fix a real bug that bothers people (not a, "This could be a
    problem..." type thing).
  - It must fix a problem that causes a build error (but not for things
    marked CONFIG_BROKEN), an oops, a hang, data corruption, a real
    security issue, or some "oh, that's not good" issue.  In short, something
    critical.
  - Serious issues as reported by a user of a distribution kernel may also
    be considered if they fix a notable performance or interactivity issue.
    As these fixes are not as obvious and have a higher risk of a subtle
    regression they should only be submitted by a distribution kernel
    maintainer and include an addendum linking to a bugzilla entry if it
    exists and additional information on the user-visible impact.
  - New device IDs and quirks are also accepted.
  - No "theoretical race condition" issues, unless an explanation of how the
    race can be exploited is also provided.
  - It cannot contain any "trivial" fixes in it (spelling changes,
    whitespace cleanups, etc).
  - It must follow the
    :ref:`Documentation/process/submitting-patches.rst <submittingpatches>`
    rules.
  - It or an equivalent fix must already exist in Linus' tree (upstream).


 Procedure for submitting patches to the -stable tree
 ----------------------------------------------------

 .. note::

    Security patches should not be handled (solely) by the -stable review
    process but should follow the procedures in
    :ref:`Documentation/process/security-bugs.rst <securitybugs>`.

 For all other submissions, choose one of the following procedures
 -----------------------------------------------------------------

 .. _option_1:

 Option 1
 ********

 To have the patch automatically included in the stable tree, add the tag

 .. code-block:: none

      Cc: stable@vger.kernel.org

 in the sign-off area. Once the patch is merged it will be applied to
 the stable tree without anything else needing to be done by the author
 or subsystem maintainer.

 .. _option_2:

 Option 2
 ********

 After the patch has been merged to Linus' tree, send an email to
 stable@vger.kernel.org containing the subject of the patch, the commit ID,
 why you think it should be applied, and what kernel version you wish it to
 be applied to.

 .. _option_3:

 Option 3
 ********

 Send the patch, after verifying that it follows the above rules, to
 stable@vger.kernel.org.  You must note the upstream commit ID in the
 changelog of your submission, as well as the kernel version you wish
 it to be applied to.

 :ref:`option_1` is **strongly** preferred, is the easiest and most common.
 :ref:`option_2` and :ref:`option_3` are more useful if the patch isn't deemed
 worthy at the time it is applied to a public git tree (for instance, because
 it deserves more regression testing first).  :ref:`option_3` is especially
 useful if the original upstream patch needs to be backported (for example
 the backport needs some special handling due to e.g. API changes).

 Note that for :ref:`option_3`, if the patch deviates from the original
 upstream patch (for example because it had to be backported) this must be very
 clearly documented and justified in the patch description.

 The upstream commit ID must be specified with a separate line above the commit
 text, like this:

 .. code-block:: none

     commit <sha1> upstream.

 or alternatively:

 .. code-block:: none

     [ Upstream commit <sha1> ]

 Additionally, some patches submitted via :ref:`option_1` may have additional
 patch prerequisites which can be cherry-picked. This can be specified in the
 following format in the sign-off area:

 .. code-block:: none

      Cc: <stable@vger.kernel.org> # 3.3.x: a1f84a3: sched: Check for idle
      Cc: <stable@vger.kernel.org> # 3.3.x: 1b9508f: sched: Rate-limit newidle
      Cc: <stable@vger.kernel.org> # 3.3.x: fd21073: sched: Fix affinity logic
      Cc: <stable@vger.kernel.org> # 3.3.x
      Signed-off-by: Ingo Molnar <mingo@elte.hu>

 The tag sequence has the meaning of:

 .. code-block:: none

      git cherry-pick a1f84a3
      git cherry-pick 1b9508f
      git cherry-pick fd21073
      git cherry-pick <this commit>

 Also, some patches may have kernel version prerequisites.  This can be
 specified in the following format in the sign-off area:

 .. code-block:: none

      Cc: <stable@vger.kernel.org> # 3.3.x

 The tag has the meaning of:

 .. code-block:: none

      git cherry-pick <this commit>

 For each "-stable" tree starting with the specified version.

 Following the submission:

  - The sender will receive an ACK when the patch has been accepted into the
    queue, or a NAK if the patch is rejected.  This response might take a few
    days, according to the developer's schedules.
  - If accepted, the patch will be added to the -stable queue, for review by
    other developers and by the relevant subsystem maintainer.


 Review cycle
 ------------

  - When the -stable maintainers decide for a review cycle, the patches will be
    sent to the review committee, and the maintainer of the affected area of
    the patch (unless the submitter is the maintainer of the area) and CC: to
    the linux-kernel mailing list.
  - The review committee has 48 hours in which to ACK or NAK the patch.
  - If the patch is rejected by a member of the committee, or linux-kernel
    members object to the patch, bringing up issues that the maintainers and
    members did not realize, the patch will be dropped from the queue.
  - The ACKed patches will be posted again as part of release candidate (-rc)
    to be tested by developers and testers.
  - Usually only one -rc release is made, however if there are any outstanding
    issues, some patches may be modified or dropped or additional patches may
    be queued. Additional -rc releases are then released and tested until no
    issues are found.
  - Responding to the -rc releases can be done on the mailing list by sending
    a "Tested-by:" email with any testing information desired. The "Tested-by:"
    tags will be collected and added to the release commit.
  - At the end of the review cycle, the new -stable release will be released
    containing all the queued and tested patches.
  - Security patches will be accepted into the -stable tree directly from the
    security kernel team, and not go through the normal review cycle.
    Contact the kernel security team for more details on this procedure.

 Trees
 -----

  - The queues of patches, for both completed versions and in progress
    versions can be found at:

 	https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git

  - The finalized and tagged releases of all stable kernels can be found
    in separate branches per version at:

 	https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

  - The release candidate of all stable kernel versions can be found at:

         https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/

    .. warning::
       The -stable-rc tree is a snapshot in time of the stable-queue tree and
       will change frequently, hence will be rebased often. It should only be
       used for testing purposes (e.g. to be consumed by CI systems).


 Review committee
 ----------------

  - This is made up of a number of kernel developers who have volunteered for
    this task, and a few that haven't.
	.. _stable_kernel_rules:

	Everything you ever wanted to know about Linux -stable releases
	===============================================================

	Rules on what kind of patches are accepted, and which ones are not, into the
	"-stable" tree:

	- It must be obviously correct and tested.
	- It cannot be bigger than 100 lines, with context.
	- It must fix only one thing.
	- It must fix a real bug that bothers people (not a, "This could be a
	problem..." type thing).
	- It must fix a problem that causes a build error (but not for things
	marked CONFIG_BROKEN), an oops, a hang, data corruption, a real
	security issue, or some "oh, that's not good" issue. In short, something
	critical.
	- Serious issues as reported by a user of a distribution kernel may also
	be considered if they fix a notable performance or interactivity issue.
	As these fixes are not as obvious and have a higher risk of a subtle
	regression they should only be submitted by a distribution kernel
	maintainer and include an addendum linking to a bugzilla entry if it
	exists and additional information on the user-visible impact.
	- New device IDs and quirks are also accepted.
	- No "theoretical race condition" issues, unless an explanation of how the
	race can be exploited is also provided.
	- It cannot contain any "trivial" fixes in it (spelling changes,
	whitespace cleanups, etc).
	- It must follow the
	:ref:`Documentation/process/submitting-patches.rst <submittingpatches>`
	rules.
	- It or an equivalent fix must already exist in Linus' tree (upstream).


	Procedure for submitting patches to the -stable tree
	----------------------------------------------------

	.. note::

	Security patches should not be handled (solely) by the -stable review
	process but should follow the procedures in
	:ref:`Documentation/process/security-bugs.rst <securitybugs>`.

	For all other submissions, choose one of the following procedures
	-----------------------------------------------------------------

	.. _option_1:

	Option 1
	********

	To have the patch automatically included in the stable tree, add the tag

	.. code-block:: none

	Cc: stable@vger.kernel.org

	in the sign-off area. Once the patch is merged it will be applied to
	the stable tree without anything else needing to be done by the author
	or subsystem maintainer.

	.. _option_2:

	Option 2
	********

	After the patch has been merged to Linus' tree, send an email to
	stable@vger.kernel.org containing the subject of the patch, the commit ID,
	why you think it should be applied, and what kernel version you wish it to
	be applied to.

	.. _option_3:

	Option 3
	********

	Send the patch, after verifying that it follows the above rules, to
	stable@vger.kernel.org. You must note the upstream commit ID in the
	changelog of your submission, as well as the kernel version you wish
	it to be applied to.

	:ref:`option_1` is strongly preferred, is the easiest and most common.
	:ref:`option_2` and :ref:`option_3` are more useful if the patch isn't deemed
	worthy at the time it is applied to a public git tree (for instance, because
	it deserves more regression testing first). :ref:`option_3` is especially
	useful if the original upstream patch needs to be backported (for example
	the backport needs some special handling due to e.g. API changes).

	Note that for :ref:`option_3`, if the patch deviates from the original
	upstream patch (for example because it had to be backported) this must be very
	clearly documented and justified in the patch description.

	The upstream commit ID must be specified with a separate line above the commit
	text, like this:

	.. code-block:: none

	commit <sha1> upstream.

	or alternatively:

	.. code-block:: none

	[ Upstream commit <sha1> ]

	Additionally, some patches submitted via :ref:`option_1` may have additional
	patch prerequisites which can be cherry-picked. This can be specified in the
	following format in the sign-off area:

	.. code-block:: none

	Cc: <stable@vger.kernel.org> # 3.3.x: a1f84a3: sched: Check for idle
	Cc: <stable@vger.kernel.org> # 3.3.x: 1b9508f: sched: Rate-limit newidle
	Cc: <stable@vger.kernel.org> # 3.3.x: fd21073: sched: Fix affinity logic
	Cc: <stable@vger.kernel.org> # 3.3.x
	Signed-off-by: Ingo Molnar <mingo@elte.hu>

	The tag sequence has the meaning of:

	.. code-block:: none

	git cherry-pick a1f84a3
	git cherry-pick 1b9508f
	git cherry-pick fd21073
	git cherry-pick <this commit>

	Also, some patches may have kernel version prerequisites. This can be
	specified in the following format in the sign-off area:

	.. code-block:: none

	Cc: <stable@vger.kernel.org> # 3.3.x

	The tag has the meaning of:

	.. code-block:: none

	git cherry-pick <this commit>

	For each "-stable" tree starting with the specified version.

	Following the submission:

	- The sender will receive an ACK when the patch has been accepted into the
	queue, or a NAK if the patch is rejected. This response might take a few
	days, according to the developer's schedules.
	- If accepted, the patch will be added to the -stable queue, for review by
	other developers and by the relevant subsystem maintainer.


	Review cycle
	------------

	- When the -stable maintainers decide for a review cycle, the patches will be
	sent to the review committee, and the maintainer of the affected area of
	the patch (unless the submitter is the maintainer of the area) and CC: to
	the linux-kernel mailing list.
	- The review committee has 48 hours in which to ACK or NAK the patch.
	- If the patch is rejected by a member of the committee, or linux-kernel
	members object to the patch, bringing up issues that the maintainers and
	members did not realize, the patch will be dropped from the queue.
	- The ACKed patches will be posted again as part of release candidate (-rc)
	to be tested by developers and testers.
	- Usually only one -rc release is made, however if there are any outstanding
	issues, some patches may be modified or dropped or additional patches may
	be queued. Additional -rc releases are then released and tested until no
	issues are found.
	- Responding to the -rc releases can be done on the mailing list by sending
	a "Tested-by:" email with any testing information desired. The "Tested-by:"
	tags will be collected and added to the release commit.
	- At the end of the review cycle, the new -stable release will be released
	containing all the queued and tested patches.
	- Security patches will be accepted into the -stable tree directly from the
	security kernel team, and not go through the normal review cycle.
	Contact the kernel security team for more details on this procedure.

	Trees
	-----

	- The queues of patches, for both completed versions and in progress
	versions can be found at:

	https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git

	- The finalized and tagged releases of all stable kernels can be found
	in separate branches per version at:

	https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

	- The release candidate of all stable kernel versions can be found at:

	https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/

	.. warning::
	The -stable-rc tree is a snapshot in time of the stable-queue tree and
	will change frequently, hence will be rebased often. It should only be
	used for testing purposes (e.g. to be consumed by CI systems).


	Review committee
	----------------

	- This is made up of a number of kernel developers who have volunteered for
	this task, and a few that haven't.