coccinelle: check for casting malloc output

Casting the (void *) output of memory allocation functions before
assignment like in

	sata->cmd_hdr_tbl_offset = (void *)malloc(length + align);

is useless.

Adopt the Linux kernel script
scripts/coccinelle/api/alloc/alloc_cast.cocci.

Now 'make coccicheck' generates warnings like:

./drivers/ata/fsl_sata.c:143:29-33:
WARNING: casting value returned by memory allocation function
to (void *) is useless.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
This commit is contained in:
Heinrich Schuchardt 2020-04-19 11:07:34 +02:00 committed by Tom Rini
parent b5a2046376
commit cb2a2ebd4f

View file

@ -0,0 +1,102 @@
// SPDX-License-Identifier: GPL-2.0-only
/// Remove casting the values returned by memory allocation functions
/// like kmalloc, kzalloc, kmem_cache_alloc, kmem_cache_zalloc etc.
///
//# This makes an effort to find cases of casting of values returned by
//# malloc, calloc, kmalloc, kmalloc_array, kmalloc_node and removes
//# the casting as it is not required. The result in the patch case may
//# need some reformatting.
//
// Confidence: High
// Copyright: (C) 2014 Himangi Saraogi
// Copyright: (C) 2017 Himanshu Jha
// Comments:
// Options: --no-includes --include-headers
//
virtual context
virtual patch
virtual org
virtual report
@initialize:python@
@@
import re
pattern = '__'
m = re.compile(pattern)
@r1 depends on context || patch@
type T;
@@
(T *)
\(malloc\|calloc\|kmalloc\|kmalloc_array\|kmalloc_node\)(...)
//----------------------------------------------------------
// For context mode
//----------------------------------------------------------
@script:python depends on context@
t << r1.T;
@@
if m.search(t) != None:
cocci.include_match(False)
@depends on context && r1@
type r1.T;
@@
* (T *)
\(malloc\|calloc\|kmalloc\|kmalloc_array\|kmalloc_node\)(...)
//----------------------------------------------------------
// For patch mode
//----------------------------------------------------------
@script:python depends on patch@
t << r1.T;
@@
if m.search(t) != None:
cocci.include_match(False)
@depends on patch && r1@
type r1.T;
@@
- (T *)
\(malloc\|calloc\|kmalloc\|kmalloc_array\|kmalloc_node\)(...)
//----------------------------------------------------------
// For org and report mode
//----------------------------------------------------------
@r2 depends on org || report@
type T;
position p;
@@
(T@p *)
\(malloc\|calloc\|kmalloc\|kmalloc_array\|kmalloc_node\)(...)
@script:python depends on org@
p << r2.p;
t << r2.T;
@@
if m.search(t) != None:
cocci.include_match(False)
else:
coccilib.org.print_safe_todo(p[0], t)
@script:python depends on report@
p << r2.p;
t << r2.T;
@@
if m.search(t) != None:
cocci.include_match(False)
else:
msg="WARNING: casting value returned by memory allocation function to (%s *) is useless." % (t)
coccilib.report.print_report(p[0], msg)