Coccinelle: add api/d_find_alias.cocci

Ensure that calls to d_find_alias() have a corresponding dput().
Signed-off-by: NCyril Roelandt <tipecaml@gmail.com>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Cc: Gilles Muller <Gilles.Muller@lip6.fr>
Cc: Nicolas Palix <nicolas.palix@imag.fr>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

scripts/coccinelle/api/d_find_alias.cocci

+/// Make sure calls to d_find_alias() have a corresponding call to dput().
+//
+// Keywords: d_find_alias, dput
+//
+// Confidence: Moderate
+// URL: http://coccinelle.lip6.fr/
+// Options: -include_headers
+
+virtual context
+virtual org
+virtual patch
+virtual report
+
+@r exists@
+local idexpression struct dentry *dent;
+expression E, E1;
+statement S1, S2;
+position p1, p2;
+@@
+(
+	if (!(dent@p1 = d_find_alias(...))) S1
+|
+	dent@p1 = d_find_alias(...)
+)
+
+<...when != dput(dent)
+    when != if (...) { <+... dput(dent) ...+> }
+    when != true !dent || ...
+    when != dent = E
+    when != E = dent
+if (!dent || ...) S2
+...>
+(
+	return <+...dent...+>;
+|
+	return @p2 ...;
+|
+	dent@p2 = E1;
+|
+	E1 = dent;
+)
+
+@depends on context@
+local idexpression struct dentry *r.dent;
+position r.p1,r.p2;
+@@
+* dent@p1 = ...
+  ...
+(
+* return@p2 ...;
+|
+* dent@p2
+)
+
+
+@script:python depends on org@
+p1 << r.p1;
+p2 << r.p2;
+@@
+cocci.print_main("Missing call to dput()",p1)
+cocci.print_secs("",p2)
+
+@depends on patch@
+local idexpression struct dentry *r.dent;
+position r.p2;
+@@
+(
++ dput(dent);
+  return @p2 ...;
+|
++ dput(dent);
+  dent@p2 = ...;
+)
+
+@script:python depends on report@
+p1 << r.p1;
+p2 << r.p2;
+@@
+msg = "Missing call to dput() at line %s."
+coccilib.report.print_report(p1[0], msg % (p2[0].line))