Add a description to the MACRO_ARG_REUSE check.
I feel like this is also a good place to put a workaround although I'm
not sure if there is a cannonical way to solve those kinds of issues.
Signed-off-by: Martin Fernandez <martin.fernandez@xxxxxxxxxxxxx>
---
Documentation/dev-tools/checkpatch.rst | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/Documentation/dev-tools/checkpatch.rst b/Documentation/dev-tools/checkpatch.rst
index b52452bc2963..43fa99f188f5 100644
--- a/Documentation/dev-tools/checkpatch.rst
+++ b/Documentation/dev-tools/checkpatch.rst
@@ -759,6 +759,21 @@ Indentation and Line Breaks
Macros, Attributes and Symbols
------------------------------
+ **ARG_REUSE**
+ Using the same argument multiple times in the macro definition
+ would lead to unwanted side-effects.
+
+ For example, given a `min` macro defined like::
+
+ #define min(x, y) ((x) < (y) ? (x) : (y))
+
+ If you call it with `min(foo(x), 0)` would expand to::
+
+ foo(x) < 0 ? foo(x) : 0
+
+ If `foo` have side-effects or it's an expensive calculation the
+ results might not be what the user inteded.
+
**ARRAY_SIZE**
The ARRAY_SIZE(foo) macro should be preferred over
sizeof(foo)/sizeof(foo[0]) for finding number of elements in an
--
2.30.2
