Provided by: systemtap-doc_2.3-1ubuntu1.4_all 

NAME
function::tcpmib_filter_key - Default filter function for tcpmib.* probes
SYNOPSIS
tcpmib_filter_key:long(sk:long,op:long)
ARGUMENTS
sk pointer to the struct sock being acted on op value to be counted if sk passes the filter
DESCRIPTION
This function is a default filter function. The user can replace this function with their own. The user-supplied filter function returns an index key based on the values in sk. A return value of 0 means this particular sk should be not be counted.