checkpatch: check for common memset parameter issues against statments

Move the memset checks over to work against the statement.  Also add
checks for 0 and 1 used as lengths.  Generally these indicate badly
ordered parameters.
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -3120,6 +3120,28 @@ sub process {
 			     "Avoid line continuations in quoted strings\n" . $herecurr);
 		}
 
+# Check for misused memsets
+		if (defined $stat && $stat =~ /\bmemset\s*\((.*)\)/s) {
+			my $args = $1;
+
+			# Flatten any parentheses and braces
+			while ($args =~ s/\([^\(\)]*\)/10/s ||
+			       $args =~ s/\{[^\{\}]*\}/10/s ||
+			       $args =~ s/\[[^\[\]]*\]/10/s)
+			{
+			}
+			# Extract the simplified arguments.
+			my ($ms_addr, $ms_val, $ms_size) =
+						split(/\s*,\s*/, $args);
+			if ($ms_size =~ /^(0x|)0$/i) {
+				ERROR("MEMSET",
+				      "memset size is 3rd argument, not the second.\n" . $herecurr);
+			} elsif ($ms_size =~ /^(0x|)1$/i) {
+				WARN("MEMSET",
+				     "single byte memset is suspicious. Swapped 2nd/3rd argument?\n" . $herecurr);
+			}
+		}
+
 # check for new externs in .c files.
 		if ($realfile =~ /\.c$/ && defined $stat &&
 		    $stat =~ /^.\s*(?:extern\s+)?$Type\s+($Ident)(\s*)\(/s)
@@ -3291,12 +3313,6 @@ sub process {
 			WARN("EXPORTED_WORLD_WRITABLE",
 			     "Exporting world writable files is usually an error. Consider more restrictive permissions.\n" . $herecurr);
 		}
-
-		# Check for memset with swapped arguments
-		if ($line =~ /memset.*\,(\ |)(0x|)0(\ |0|)\);/) {
-			ERROR("MEMSET",
-			      "memset size is 3rd argument, not the second.\n" . $herecurr);
-		}
 	}
 
 	# If we have no input at all, then there is nothing to report on