[PATCH] checkpatch: Test for kmalloc/memset(0) pairs

[Steven Rostedt <rostedt@goodmis.org>]

The use of kzalloc() is preferred over kmalloc/memset(0) pairs.

When a match is made with "memset(p, 0, s);" a search back through the
patch hunk is made looking for "p = kmalloc(s,". If that is found, then
a warning is given, suggesting to use kzalloc() instead.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 58848e3..f28f0e3 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2902,6 +2902,22 @@ sub process {
 		    $line =~ /DEVICE_ATTR.*S_IWUGO/ ) {
 			WARN("Exporting world writable files is usually an error. Consider more restrictive permissions.\n" . $herecurr);
 		}
+
+# The use of kzalloc() is preferred over kmalloc/memset(0) pairs.
+		if ($line =~ /\smemset\s*\((\S*)\s*,\s*(?:0x0|0)\s*,\s*(\S*)\s*\);/) {
+		    my $ptr = $1;
+		    my $size = $2;
+
+		    for (my $i = $linenr-2; $i >= 0; $i--) {
+			next if ($lines[$i] =~ /^-/); # ignore deletions
+			last if ($lines[$i] =~ /^\@\@/);
+			if ($lines[$i] =~ /\s(\S*)\s*=\s*kmalloc\((\S*)\,/ &&
+			    $1 eq $ptr && $2 eq $size) {
+			    WARN("use kzalloc() instead of kmalloc/memset(p,0,size) pair\n"
+				 . $herecurr);
+			}
+		    }
+		}
 	}
 
 	# If we have no input at all, then there is nothing to report on