1 .. _submitchecklist:
2
3 =======================================
4 Linux Kernel patch submission checklist
5 =======================================
6
7 Here are some basic things that developers should do if they want to see their
8 kernel patch submissions accepted more quickly.
9
10 These are all above and beyond the documentation that is provided in
11 :ref:`Documentation/process/submitting-patches.rst <submittingpatches>`
12 and elsewhere regarding submitting Linux kernel patches.
13
14 Review your code
15 ================
16
17 1) If you use a facility then #include the file that defines/declares
18 that facility. Don't depend on other header files pulling in ones
19 that you use.
20
21 2) Check your patch for general style as detailed in
22 :ref:`Documentation/process/coding-style.rst <codingstyle>`.
23
24 3) All memory barriers {e.g., ``barrier()``, ``rmb()``, ``wmb()``} need a
25 comment in the source code that explains the logic of what they are doing
26 and why.
27
28 Review Kconfig changes
29 ======================
30
31 1) Any new or modified ``CONFIG`` options do not muck up the config menu and
32 default to off unless they meet the exception criteria documented in
33 ``Documentation/kbuild/kconfig-language.rst`` Menu attributes: default value.
34
35 2) All new ``Kconfig`` options have help text.
36
37 3) Has been carefully reviewed with respect to relevant ``Kconfig``
38 combinations. This is very hard to get right with testing---brainpower
39 pays off here.
40
41 Provide documentation
42 =====================
43
44 1) Include :ref:`kernel-doc <kernel_doc>` to document global kernel APIs.
45 (Not required for static functions, but OK there also.)
46
47 2) All new ``/proc`` entries are documented under ``Documentation/``
48
49 3) All new kernel boot parameters are documented in
50 ``Documentation/admin-guide/kernel-parameters.rst``.
51
52 4) All new module parameters are documented with ``MODULE_PARM_DESC()``
53
54 5) All new userspace interfaces are documented in ``Documentation/ABI/``.
55 See ``Documentation/ABI/README`` for more information.
56 Patches that change userspace interfaces should be CCed to
57 linux-api@vger.kernel.org.
58
59 6) If any ioctl's are added by the patch, then also update
60 ``Documentation/userspace-api/ioctl/ioctl-number.rst``.
61
62 Check your code with tools
63 ==========================
64
65 1) Check for trivial violations with the patch style checker prior to
66 submission (``scripts/checkpatch.pl``).
67 You should be able to justify all violations that remain in
68 your patch.
69
70 2) Check cleanly with sparse.
71
72 3) Use ``make checkstack`` and fix any problems that it finds.
73 Note that ``checkstack`` does not point out problems explicitly,
74 but any one function that uses more than 512 bytes on the stack is a
75 candidate for change.
76
77 Build your code
78 ===============
79
80 1) Builds cleanly:
81
82 a) with applicable or modified ``CONFIG`` options ``=y``, ``=m``, and
83 ``=n``. No ``gcc`` warnings/errors, no linker warnings/errors.
84
85 b) Passes ``allnoconfig``, ``allmodconfig``
86
87 c) Builds successfully when using ``O=builddir``
88
89 d) Any Documentation/ changes build successfully without new warnings/errors.
90 Use ``make htmldocs`` or ``make pdfdocs`` to check the build and
91 fix any issues.
92
93 2) Builds on multiple CPU architectures by using local cross-compile tools
94 or some other build farm. Note that ppc64 is a good architecture for
95 cross-compilation checking because it tends to use ``unsigned long`` for
96 64-bit quantities.
97
98 3) Newly-added code has been compiled with ``gcc -W`` (use
99 ``make KCFLAGS=-W``). This will generate lots of noise, but is good
100 for finding bugs like "warning: comparison between signed and unsigned".
101
102 4) If your modified source code depends on or uses any of the kernel
103 APIs or features that are related to the following ``Kconfig`` symbols,
104 then test multiple builds with the related ``Kconfig`` symbols disabled
105 and/or ``=m`` (if that option is available) [not all of these at the
106 same time, just various/random combinations of them]:
107
108 ``CONFIG_SMP``, ``CONFIG_SYSFS``, ``CONFIG_PROC_FS``, ``CONFIG_INPUT``,
109 ``CONFIG_PCI``, ``CONFIG_BLOCK``, ``CONFIG_PM``, ``CONFIG_MAGIC_SYSRQ``,
110 ``CONFIG_NET``, ``CONFIG_INET=n`` (but latter with ``CONFIG_NET=y``).
111
112 Test your code
113 ==============
114
115 1) Has been tested with ``CONFIG_PREEMPT``, ``CONFIG_DEBUG_PREEMPT``,
116 ``CONFIG_SLUB_DEBUG``, ``CONFIG_DEBUG_PAGEALLOC``, ``CONFIG_DEBUG_MUTEXES``,
117 ``CONFIG_DEBUG_SPINLOCK``, ``CONFIG_DEBUG_ATOMIC_SLEEP``,
118 ``CONFIG_PROVE_RCU`` and ``CONFIG_DEBUG_OBJECTS_RCU_HEAD`` all
119 simultaneously enabled.
120
121 2) Has been build- and runtime tested with and without ``CONFIG_SMP`` and
122 ``CONFIG_PREEMPT.``
123
124 3) All codepaths have been exercised with all lockdep features enabled.
125
126 4) Has been checked with injection of at least slab and page-allocation
127 failures. See ``Documentation/fault-injection/``.
128 If the new code is substantial, addition of subsystem-specific fault
129 injection might be appropriate.
130
131 5) Tested with the most recent tag of linux-next to make sure that it still
132 works with all of the other queued patches and various changes in the VM,
133 VFS, and other subsystems.
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