[PATCH 03/10] docs: sphinxify sparse.txt and move to dev-tools

From: Jonathan Corbet
Date: Mon Aug 08 2016 - 19:37:36 EST


Fold the sparse document into the development tools set; no changes to the
text itself beyond formatting.

Signed-off-by: Jonathan Corbet <corbet@xxxxxxx>
---
Documentation/{sparse.txt => dev-tools/sparse.rst} | 61 +++++++++++++---------
Documentation/dev-tools/tools.rst | 1 +
2 files changed, 36 insertions(+), 26 deletions(-)
rename Documentation/{sparse.txt => dev-tools/sparse.rst} (61%)

diff --git a/Documentation/sparse.txt b/Documentation/dev-tools/sparse.rst
similarity index 61%
rename from Documentation/sparse.txt
rename to Documentation/dev-tools/sparse.rst
index eceab13..ebb6087 100644
--- a/Documentation/sparse.txt
+++ b/Documentation/dev-tools/sparse.rst
@@ -1,11 +1,20 @@
-Copyright 2004 Linus Torvalds
-Copyright 2004 Pavel Machek <pavel@xxxxxx>
-Copyright 2006 Bob Copeland <me@xxxxxxxxxxxxxxx>
+.. Copyright 2004 Linus Torvalds
+.. Copyright 2004 Pavel Machek <pavel@xxxxxx>
+.. Copyright 2006 Bob Copeland <me@xxxxxxxxxxxxxxx>
+
+Sparse
+======
+
+Sparse is a semantic checker for C programs; it can be used to find a
+number of potential problems with kernel code. See
+https://lwn.net/Articles/689907/ for an overview of sparse; this document
+contains some kernel-specific sparse information.
+

Using sparse for typechecking
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+-----------------------------

-"__bitwise" is a type attribute, so you have to do something like this:
+``__bitwise`` is a type attribute, so you have to do something like this::

typedef int __bitwise pm_request_t;

@@ -14,19 +23,19 @@ Using sparse for typechecking
PM_RESUME = (__force pm_request_t) 2
};

-which makes PM_SUSPEND and PM_RESUME "bitwise" integers (the "__force" is
+which makes PM_SUSPEND and PM_RESUME ``bitwise`` integers (the ``__force`` is
there because sparse will complain about casting to/from a bitwise type,
but in this case we really _do_ want to force the conversion). And because
-the enum values are all the same type, now "enum pm_request" will be that
+the enum values are all the same type, now ``enum pm_request`` will be that
type too.

-And with gcc, all the __bitwise/__force stuff goes away, and it all ends
-up looking just like integers to gcc.
+And with gcc, all the ``__bitwise``/``__force stuff`` goes away, and it all
+ends up looking just like integers to gcc.

Quite frankly, you don't need the enum there. The above all really just
-boils down to one special "int __bitwise" type.
+boils down to one special ``int __bitwise`` type.

-So the simpler way is to just do
+So the simpler way is to just do::

typedef int __bitwise pm_request_t;

@@ -35,11 +44,11 @@ So the simpler way is to just do

and you now have all the infrastructure needed for strict typechecking.

-One small note: the constant integer "0" is special. You can use a
+One small note: the constant integer ``0`` is special. You can use a
constant zero as a bitwise integer type without sparse ever complaining.
-This is because "bitwise" (as the name implies) was designed for making
+This is because ``bitwise`` (as the name implies) was designed for making
sure that bitwise types don't get mixed up (little-endian vs big-endian
-vs cpu-endian vs whatever), and there the constant "0" really _is_
+vs cpu-endian vs whatever), and there the constant ``0`` really _is_
special.

__bitwise__ - to be used for relatively compact stuff (gfp_t, etc.) that
@@ -50,18 +59,18 @@ __bitwise - noisy stuff; in particular, __le*/__be* are that. We really
don't want to drown in noise unless we'd explicitly asked for it.

Using sparse for lock checking
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+------------------------------

The following macros are undefined for gcc and defined during a sparse
run to use the "context" tracking feature of sparse, applied to
locking. These annotations tell sparse when a lock is held, with
regard to the annotated function's entry and exit.

-__must_hold - The specified lock is held on function entry and exit.
+``__must_hold`` - The specified lock is held on function entry and exit.

-__acquires - The specified lock is held on function exit, but not entry.
+``__acquires`` - The specified lock is held on function exit, but not entry.

-__releases - The specified lock is held on function entry, but not exit.
+``__releases`` - The specified lock is held on function entry, but not exit.

If the function enters and exits without the lock held, acquiring and
releasing the lock inside the function in a balanced way, no
@@ -69,22 +78,22 @@ annotation is needed. The tree annotations above are for cases where
sparse would otherwise report a context imbalance.

Getting sparse
-~~~~~~~~~~~~~~
+--------------

You can get latest released versions from the Sparse homepage at
https://sparse.wiki.kernel.org/index.php/Main_Page

Alternatively, you can get snapshots of the latest development version
-of sparse using git to clone..
+of sparse using git to clone::

git://git.kernel.org/pub/scm/devel/sparse/sparse.git

-DaveJ has hourly generated tarballs of the git tree available at..
+DaveJ has hourly generated tarballs of the git tree available at::

http://www.codemonkey.org.uk/projects/git-snapshots/sparse/


-Once you have it, just do
+Once you have it, just do::

make
make install
@@ -92,16 +101,16 @@ Once you have it, just do
as a regular user, and it will install sparse in your ~/bin directory.

Using sparse
-~~~~~~~~~~~~
+------------

-Do a kernel make with "make C=1" to run sparse on all the C files that get
-recompiled, or use "make C=2" to run sparse on the files whether they need to
+Do a kernel make with ``make C=1`` to run sparse on all the C files that get
+recompiled, or use ``make C=2`` to run sparse on the files whether they need to
be recompiled or not. The latter is a fast way to check the whole tree if you
have already built it.

The optional make variable CF can be used to pass arguments to sparse. The
build system passes -Wbitwise to sparse automatically. To perform endianness
-checks, you may define __CHECK_ENDIAN__:
+checks, you may define ``__CHECK_ENDIAN__``::

make C=2 CF="-D__CHECK_ENDIAN__"

diff --git a/Documentation/dev-tools/tools.rst b/Documentation/dev-tools/tools.rst
index ae0c58c..d4bbda3 100644
--- a/Documentation/dev-tools/tools.rst
+++ b/Documentation/dev-tools/tools.rst
@@ -15,3 +15,4 @@ whole; patches welcome!
:maxdepth: 2

coccinelle
+ sparse
--
2.9.2