checkpatch: warn on break after goto or return with same tab indentation

Using break; after a goto or return is unnecessary so emit a warning
when the break is at the same indent level.

So this emits a warning on:

	switch (foo) {
	case 1:
		goto err;
		break;
	}

but not on:

	switch (foo) {
	case 1:
		if (bar())
			goto err;
		break;
	}
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -2450,6 +2450,16 @@ sub process {
 			}
 		}
 
+# check indentation of a line with a break;
+# if the previous line is a goto or return and is indented the same # of tabs
+		if ($sline =~ /^\+([\t]+)break\s*;\s*$/) {
+			my $tabs = $1;
+			if ($prevline =~ /^\+$tabs(?:goto|return)\b/) {
+				WARN("UNNECESSARY_BREAK",
+				     "break is not useful after a goto or return\n" . $hereprev);
+			}
+		}
+
 # discourage the addition of CONFIG_EXPERIMENTAL in #if(def).
 		if ($line =~ /^\+\s*\#\s*if.*\bCONFIG_EXPERIMENTAL\b/) {
 			WARN("CONFIG_EXPERIMENTAL",