# login.pl

use CGI;
use CGI::Session ( '-ip_match' );
use DBI;

use MyPM qw(&open_db &close_db &getSession); 

use strict;
use warnings;

my $cgi = new CGI;
my $dbh = open_db;
my $session = getSession($cgi, $dbh);   # Call to MyPM.pm
close_db($dbh);

...... code ......

print $session->header(-type => 'application/json');
print $json;

=======================================

# MyPM.pm

use CGI::Session ( '-ip_match' );

our @ISA = qw(Exporter);
our @EXPORT_OK = qw( open_db close_db getSession );

sub getSession {  

  my $cgi = shift;
  my $dbh = shift;

  my $CGICOOKIE = $cgi->cookie('CGISESSID') || 'x';
  my $lng = length($CGICOOKIE);
  if ( $lng != 32 ) print redirect( -URL => $home );

  my $session = CGI::Session->new('driver:MySQL', $cgi, {Handle=>$dbh}) ;
  return $session; 

}

##</code><code>##

my $session = CGI::Session->new('driver:MySQL', $cgi, {Handle=>$dbh});