Re: [coccicheck Linux 3.14-rc5 PATCH 4 of 5] Deletion of unnecessary checks before specific function

SF Markus Elfring
2014-03-05T22:55:49Z

>> If you are convinced that dropping the null tests is a good idea, then you
>> can submit the patch that makes the change to the relevant maintainers and
>> mailing lists.

From e6a21b920fcca2f6f01c9528909dc036a9b3bc41 Mon Sep 17 00:00:00 2001
From: Markus Elfring <elfring@users.sourceforge.net>
Date: Wed, 5 Mar 2014 19:10:32 +0100
Subject: [PATCH 4/5] Addition of a semantic patch file for listing of
unnecessary checks before a few known functions

This semantic patch pattern tries to find source code places where a check
is performed for an expression that is passed to a function (like "kfree")
which checks this single parameter itself for usability.
Redundant value or pointer checks can be avoided here.

The pattern contains a special comment in a regular expression for a SmPL
constraint which supports extensions.

It uses Python statements to write information about the found places in
a data format that is a variant of a CSV text file.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
...nctions_with_unnecessary_checks_template1.cocci | 59 ++++++++++++++++++++++
1 file changed, 59 insertions(+)
create mode 100644
scripts/coccinelle/deletions/list_functions_with_unnecessary_checks_template1.cocci

diff --git
a/scripts/coccinelle/deletions/list_functions_with_unnecessary_checks_template1.cocci
b/scripts/coccinelle/deletions/list_functions_with_unnecessary_checks_template1.cocci
new file mode 100644
index 0000000..d2637e8
--- /dev/null
+++
b/scripts/coccinelle/deletions/list_functions_with_unnecessary_checks_template1.cocci
@@ -0,0 +1,59 @@
+@initialize:python@
+@@
+import sys
+result = []
+mark = ['"', '', '"']
+delimiter = '|'
+
+def store_positions(fun, point, places):
+ """Add source code positions to an internal list."""
+ for place in places:
+ fields = []
+ fields.append(fun)
+
+ fields.append(point)
+
+ mark[1] = place.file.replace('"', '""')
+ fields.append(''.join(mark))
+
+ fields.append(place.line)
+ fields.append(str(int(place.column) + 1))
+ result.append(delimiter.join(fields))
+
+@is_unnecessary_check@
+expression data;
+identifier work;
+identifier release =~ "^(?x)
+(?:
+ (?:kz?|slob_)free
+|
+ (?:
+# Alternation placeholder
+ )
+)$";
+position pos;
+type t;
+@@
+ t work@pos(...)
+ {
+ ... when any
+( if (data) release(data);
+| if (likely(data)) release(data);
+)
+ ... when any
+ }
+
+@script:python collection depends on is_unnecessary_check@
+fun << is_unnecessary_check.work;
+point << is_unnecessary_check.data;
+places << is_unnecessary_check.pos;
+@@
+store_positions(fun, point, places)
+
+@finalize:python@
+@@
+if result:
+ result.insert(0, delimiter.join(("function", '"parameter"', '"source file"',
"line", "column")))
+ print("\r\n".join(result))
+else:
+ sys.stderr.write("No result for this analysis!\n")
--
1.9.0