[lttng-dev] Can I use function to retrieve socket information in the SC_TRACE_EVENT macro?

[Rui Han]

Dear all,

I am working on retrieving socket information for socket related syscalls
by the kernel trace, such as sys_connect() and sys_bind(). What I did is in
the .h file
"instrumentation/syscalls/headers/x86-64-syscalls-3.0.4_pointers.h", I
modify the sys_connect SC_TRACE_EVENT. I add _field(size_t, port) and
tp_assign(port, getport() ) to the TP_STRUCT_entry() and TP_fast_assign(),
respectively. The getport() function is a function I wrote to retrieve the
port number and ip address by the function getpeername(). The lttng module
got installed correctly after the modification, (with some #ifndef
manipulations), However, when I reboot the machine and try to do the kernel
trace. It gives me error messages:

Spawning a session daemon
FATAL: Error inserting lttng_tracer
(/lib/modules/3.2.0-29-generic/extra/lttng-tracer.ko): Unknown symbol in
module, or unknown parameter (see dmesg)
Error: Unable to load module lttng-tracer
Warning: No kernel tracer available
Warning: No tracing group detected
Session rui-session created.
Traces will be written in /root/lttng-traces/rui-session-20120813-133953
FATAL: Error inserting lttng_tracer
(/lib/modules/3.2.0-29-generic/extra/lttng-tracer.ko): Unknown symbol in
module, or unknown parameter (see dmesg)
Error: Unable to load module lttng-tracer
Warning: No kernel tracer available

and in the syslog file: I got the following error:
[   82.001603] lttng_tracer: Unknown symbol getport (err 0)
[   82.377213] lttng_tracer: Unknown symbol getport (err 0)

I am new to the kernel module programming. My question is: should I do some
kinds of symbol register before define a function in the kernel space? Any
suggestion for solving the problem?

Thanks,
Rui
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