The third exercise of section 2.3 "Exercises" for the official systemtap tutorial

Question

Problem Description:

Listing: socket_trace.stp

probe kernel.function("*@net/socket.c").call{
    printf("%s -> %s\n", thread_indent(1), ppfunc())
}
probe kernel.function("*@net/socket.c").return {
    printf("%s <- %s\n", thread_indent(-1), ppfunc())
}

Change the listing by removing the .call modifier from the first probe. Note how function entry and function return now don't match anymore. This is because now the first probe will match both normal function entry and inlined functions. Try putting the .call modifier back and add another probe just for probe kernel.function("*@net/socket.c").return What printf statement can you come up with in the probe handler to show the inlined function entries nicely in between the .call and .return thread indented output?

I have no idea how to show that the inlined function call has occurs (if any) in the function return probe handler ? Can someone offer a hand ? Thanks in advance.

Answer 1

probe kernel.function("*@net/socket.c").inline {
    printf("%s -- %s\n", thread_indent(0), ppfunc())
}