diff options
Diffstat (limited to 'Documentation/dev-tools')
| -rw-r--r-- | Documentation/dev-tools/ktap.rst | 18 | ||||
| -rw-r--r-- | Documentation/dev-tools/kunit/architecture.rst | 2 | ||||
| -rw-r--r-- | Documentation/dev-tools/testing-overview.rst | 63 |
3 files changed, 72 insertions, 11 deletions
diff --git a/Documentation/dev-tools/ktap.rst b/Documentation/dev-tools/ktap.rst index 5ee735c6687f..d0a9565b0f44 100644 --- a/Documentation/dev-tools/ktap.rst +++ b/Documentation/dev-tools/ktap.rst @@ -115,34 +115,32 @@ The diagnostic data field is optional, and results which have neither a directive nor any diagnostic data do not need to include the "#" field separator. -Example result lines include: - -.. code-block:: none +Example result lines include:: ok 1 test_case_name The test "test_case_name" passed. -.. code-block:: none +:: not ok 1 test_case_name The test "test_case_name" failed. -.. code-block:: none +:: ok 1 test # SKIP necessary dependency unavailable The test "test" was SKIPPED with the diagnostic message "necessary dependency unavailable". -.. code-block:: none +:: not ok 1 test # TIMEOUT 30 seconds The test "test" timed out, with diagnostic data "30 seconds". -.. code-block:: none +:: ok 5 check return code # rcode=0 @@ -202,7 +200,7 @@ allowed to be either indented or not indented. An example of a test with two nested subtests: -.. code-block:: none +:: KTAP version 1 1..1 @@ -215,7 +213,7 @@ An example of a test with two nested subtests: An example format with multiple levels of nested testing: -.. code-block:: none +:: KTAP version 1 1..2 @@ -250,7 +248,7 @@ nested version line, uses a line of the form Example KTAP output -------------------- -.. code-block:: none +:: KTAP version 1 1..1 diff --git a/Documentation/dev-tools/kunit/architecture.rst b/Documentation/dev-tools/kunit/architecture.rst index ff9c85a0bff2..cf9e6e3eeae4 100644 --- a/Documentation/dev-tools/kunit/architecture.rst +++ b/Documentation/dev-tools/kunit/architecture.rst @@ -125,7 +125,7 @@ All expectations/assertions are formatted as: ``void __noreturn kunit_try_catch_throw(struct kunit_try_catch *try_catch)``. - ``kunit_try_catch_throw`` calls function: - ``void complete_and_exit(struct completion *, long) __noreturn;`` + ``void kthread_complete_and_exit(struct completion *, long) __noreturn;`` and terminates the special thread context. - ``<op>`` denotes a check with options: ``TRUE`` (supplied property diff --git a/Documentation/dev-tools/testing-overview.rst b/Documentation/dev-tools/testing-overview.rst index 65feb81edb14..0aaf6ea53608 100644 --- a/Documentation/dev-tools/testing-overview.rst +++ b/Documentation/dev-tools/testing-overview.rst @@ -115,3 +115,66 @@ 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. + +When to use Sparse and Smatch +----------------------------- + +Sparse does type checking, such as verifying that annotated variables do not +cause endianness bugs, detecting places that use ``__user`` pointers improperly, +and analyzing the compatibility of symbol initializers. + +Smatch does flow analysis and, if allowed to build the function database, it +also does cross function analysis. Smatch tries to answer questions like where +is this buffer allocated? How big is it? Can this index be controlled by the +user? Is this variable larger than that variable? + +It's generally easier to write checks in Smatch than it is to write checks in +Sparse. Nevertheless, there are some overlaps between Sparse and Smatch checks. + +Strong points of Smatch and Coccinelle +-------------------------------------- + +Coccinelle is probably the easiest for writing checks. It works before the +pre-processor so it's easier to check for bugs in macros using Coccinelle. +Coccinelle also creates patches for you, which no other tool does. + +For example, with Coccinelle you can do a mass conversion from +``kmalloc(x * size, GFP_KERNEL)`` to ``kmalloc_array(x, size, GFP_KERNEL)``, and +that's really useful. If you just created a Smatch warning and try to push the +work of converting on to the maintainers they would be annoyed. You'd have to +argue about each warning if can really overflow or not. + +Coccinelle does no analysis of variable values, which is the strong point of +Smatch. On the other hand, Coccinelle allows you to do simple things in a simple +way. |