[PATCH v3] Documentation/process/coding-style.rst: space around const

[Max Kellermann]

There are currently no rules on the placement of "const", but a recent
code submission revealed that there is clearly a preference for spaces
around it.

checkpatch.pl has no check at all for this; though it does sometimes
complain, but only because it erroneously thinks that the "*" (on
local variables) is an unary dereference operator, not a pointer type.

Current coding style for const pointers-to-pointers:

 "*const*": 2 occurrences
 "* const*": 3
 "*const *": 182
 "* const *": 681

Just const pointers:

 "*const": 2833 occurrences
 "* const": 16615

Link: https://lore.kernel.org/r/264fa39d-aed6-4a54-a085-107997078f8d@xxxxxxxxxxxx/
Link: https://lore.kernel.org/r/f511170fe61d7e7214a3a062661cf4103980dad6.camel@xxxxxxxxxxx/
Signed-off-by: Max Kellermann <max.kellermann@xxxxxxxxx>
---
V1 -> V2: removed "volatile" on gregkh's request.
V2 -> V3: moved patch changelog below the "---" line
---
 Documentation/process/coding-style.rst | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Documentation/process/coding-style.rst b/Documentation/process/coding-style.rst
index 6db37a46d305..71d62d81e506 100644
--- a/Documentation/process/coding-style.rst
+++ b/Documentation/process/coding-style.rst
@@ -271,6 +271,17 @@ adjacent to the type name.  Examples:
 	unsigned long long memparse(char *ptr, char **retptr);
 	char *match_strdup(substring_t *s);
 
+Use space around the ``const`` keyword (except when adjacent to
+parentheses).  Example:
+
+.. code-block:: c
+
+	const void *a;
+	void * const b;
+	void ** const c;
+	void * const * const d;
+	int strcmp(const char *a, const char *b);
+
 Use one space around (on each side of) most binary and ternary operators,
 such as any of these::
 
-- 
2.39.2