Add scripts/coccinelle/alloc/drop_kmalloc_cast.cocci

The purpose of this semantic patch is to remove
useless casts, as mentioned in the Linux documentation.
See Chapter 14 in Documentation/CodingStyle for more information.
Signed-off-by: Nicolas Palix <npalix@diku.dk>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/coccinelle/alloc/drop_kmalloc_cast.cocci

+///
+/// Casting (void *) value returned by kmalloc is useless
+/// as mentioned in Documentation/CodingStyle, Chap 14.
+///
+// Confidence: High
+// Copyright: 2009,2010 Nicolas Palix, DIKU.  GPLv2.
+// URL: http://coccinelle.lip6.fr/
+// Options: -no_includes -include_headers
+//
+// Keywords: kmalloc, kzalloc, kcalloc
+// Version min: < 2.6.12 kmalloc
+// Version min: < 2.6.12 kcalloc
+// Version min:   2.6.14 kzalloc
+//
+
+virtual context
+virtual patch
+virtual org
+virtual report
+
+//----------------------------------------------------------
+//  For context mode
+//----------------------------------------------------------
+
+@depends on context@
+type T;
+@@
+
+* (T *)
+  \(kmalloc\|kzalloc\|kcalloc\)(...)
+
+//----------------------------------------------------------
+//  For patch mode
+//----------------------------------------------------------
+
+@depends on patch@
+type T;
+@@
+
+- (T *)
+  \(kmalloc\|kzalloc\|kcalloc\)(...)
+
+//----------------------------------------------------------
+//  For org and report mode
+//----------------------------------------------------------
+
+@r depends on org || report@
+type T;
+position p;
+@@
+
+ (T@p *)\(kmalloc\|kzalloc\|kcalloc\)(...)
+
+@script:python depends on org@
+p << r.p;
+t << r.T;
+@@
+
+coccilib.org.print_safe_todo(p[0], t)
+
+@script:python depends on report@
+p << r.p;
+t << r.T;
+@@
+
+msg="WARNING: casting value returned by k[cmz]alloc to (%s *) is useless." % (t)
+coccilib.report.print_report(p[0], msg)