SHA256 password hash generation and verification
How about the following:

if (!$salt) {
    $salt = bin2hex(mcrypt_create_iv(32, MCRYPT_DEV_URANDOM));
} elseif (strlen($salt) !== 64)  {
    log_message('info', 'Supplied password to process_password() was not the correct 64-byte length.');
    return false;
}
// if we're here, we have a valid salt


Improvements


Removed $salt from second condition (already known to be TRUE)
Flipped length logic, moved else code into second block
Removed empty condition block