Re: [PATCH v2 1/2] Documentation: dev-tools: Add a section for static analysis tools

[Julia Lawall <julia.lawall@inria.fr>]

On Tue, 29 Mar 2022, Marcelo Schmitt wrote:

> Complement the Kernel Testing Guide documentation page by adding a
> section about static analysis tools.
>
> Signed-off-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com>
> Acked-by: Daniel Latypov <dlatypov@google.com>
> Acked-by: Dan Carpenter <dan.carpenter@oracle.com>
> Reviewed-by: David Gow <davidgow@google.com>
> Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>

Acked-by: Julia Lawall <julia.lawall@inria.fr>

> ---
> Change log:
> - Brought generic tool characteristics to the intro paragraph
> - Made explicit that these tools run at compile time
> - Added a note of caution about false positives
> - Updated Coccinelle info to make it sound better and be more skimmable
>
>  Documentation/dev-tools/testing-overview.rst | 31 ++++++++++++++++++++
>  1 file changed, 31 insertions(+)
>
> diff --git a/Documentation/dev-tools/testing-overview.rst b/Documentation/dev-tools/testing-overview.rst
> index 65feb81edb14..b5e02dd3fd94 100644
> --- a/Documentation/dev-tools/testing-overview.rst
> +++ b/Documentation/dev-tools/testing-overview.rst
> @@ -115,3 +115,34 @@ that none of these errors are occurring during the test.
>  Some of these tools integrate with KUnit or kselftest and will
>  automatically fail tests if an issue is detected.
>
> +Static Analysis Tools
> +=====================
> +
> +In addition to testing a running kernel, one can also analyze kernel source code
> +directly (**at compile time**) using **static analysis** tools. The tools
> +commonly used in the kernel allow one to inspect the whole source tree or just
> +specific files within it. They make it easier to detect and fix problems during
> +the development process.
> +
> +Sparse can help test the kernel by performing type-checking, lock checking,
> +value range checking, in addition to reporting various errors and warnings while
> +examining the code. See the Documentation/dev-tools/sparse.rst documentation
> +page for details on how to use it.
> +
> +Smatch extends Sparse and provides additional checks for programming logic
> +mistakes such as missing breaks in switch statements, unused return values on
> +error checking, forgetting to set an error code in the return of an error path,
> +etc. Smatch also has tests against more serious issues such as integer
> +overflows, null pointer dereferences, and memory leaks. See the project page at
> +http://smatch.sourceforge.net/.
> +
> +Coccinelle is another static analyzer at our disposal. Coccinelle is often used
> +to aid refactoring and collateral evolution of source code, but it can also help
> +to avoid certain bugs that occur in common code patterns. The types of tests
> +available include API tests, tests for correct usage of kernel iterators, checks
> +for the soundness of free operations, analysis of locking behavior, and further
> +tests known to help keep consistent kernel usage. See the
> +Documentation/dev-tools/coccinelle.rst documentation page for details.
> +
> +Beware, though, that static analysis tools suffer from **false positives**.
> +Errors and warns need to be evaluated carefully before attempting to fix them.
> --
> 2.35.1
>
>