LTTng » LTTng-UST

This is an issue in liburcu: this enum and its labels should have been namespaced with e.g. urcu_bp_... and URCU_BP_... Can you try doing a patch for this ?

Now that I think about it a bit more, I now remember that it's not supported to include multiple liburcu flavors within the same compile unit. We'll have to investigate further.

So it means that for now it would be impossible to add UST tracepoints to lttng-tools. Is my understanding correct?

It might work if you do not #define _LGPL_SOURCE at the top of the implementation. This will prevent inlining of urcu calls, and therefore we don't need to include urcu-bp.h from tracepoint-rcu.h.

Ok, so removing the _LGPL_SOURCE did remove the redefinitions or urcu related symbols.

But going back to the original bug, there are other redefinitions related to ust vs tools redefinitions:

In file included from /usr/local/include/lttng/ust-tracepoint-event.h:27:0,
from /usr/local/include/lttng/tracepoint-event.h:58,
from udev-monitor-provider.h:67,
from udev-monitor.c:37:
/usr/local/include/lttng/ust-events.h:252:8: error: redefinition of ‘struct lttng_event_field’
struct lttng_event_field {
^_~~~~~~~~~~~~~~
In file included from ./syscall.h:22:0,
from /usr/local/include/urcu/syscall-compat.h:33,
from /usr/local/include/urcu/arch.h:27,
from /usr/local/include/urcu/tls-compat.h:29,
from ../../../src/common/error.h:26,
from ../../../src/common/common.h:22,
from udev-monitor.c:21:
../../../include/lttng/event.h:283:8: note: originally defined here
struct lttng_event_field {
^_~~~~~~~~~~~~~~
In file included from /usr/local/include/lttng/ust-tracepoint-event.h:27:0,
from /usr/local/include/lttng/tracepoint-event.h:58,
from udev-monitor-provider.h:67,
from udev-monitor.c:37:
/usr/local/include/lttng/ust-events.h:444:8: error: redefinition of ‘struct lttng_event’
struct lttng_event {
^_~~~~~~~~
In file included from ./syscall.h:22:0,
from /usr/local/include/urcu/syscall-compat.h:33,
from /usr/local/include/urcu/arch.h:27,
from /usr/local/include/urcu/tls-compat.h:29,
from ../../../src/common/error.h:26,
from ../../../src/common/common.h:22,
from udev-monitor.c:21:
../../../include/lttng/event.h:231:8: note: originally defined here
struct lttng_event {
^_~~~~~~~~

and a few more such. And they lead to errors like this later:

./udev-monitor-provider.h: In function ‘__event_probe__udev_monitor___kvm_created’:
./udev-monitor-provider.h:43:1: error: ‘struct lttng_session’ has no member named ‘active’
TRACEPOINT_EVENT(
^
./udev-monitor-provider.h:43:1: error: ‘struct lttng_session’ has no member named ‘active’
TRACEPOINT_EVENT(
^
./udev-monitor-provider.h: In function ‘__event_probe__udev_monitor___kvm_destroyed’:
./udev-monitor-provider.h:56:1: error: ‘struct lttng_session’ has no member named ‘active’
TRACEPOINT_EVENT(
^
./udev-monitor-provider.h:56:1: error: ‘struct lttng_session’ has no member named ‘active’
TRACEPOINT_EVENT(

Since those structs with same names do not have the same structure in ust and tools

This is unexpected:

In file included from ./syscall.h:22:0,
from /usr/local/include/urcu/syscall-compat.h:33,

Basically, the file src/bin/lttng-sessiond/syscall.h overrides the system header syscall.h included from urcu/syscall-compat.h.

Can you try renaming the tools syscall.h header file to lttng-syscall.h to remove this mixup ?

By doing this, you won't end up including as a side-effect lttng/event.h, which declares the struct that conflicts with the lttng-ust code. This should only be needed if the program is a liblttng-ust-ctl user, and I don't think your daemon needs that.

Thanks,

Mathieu

oh maybe that's me then, I had to add -I./ to AM_CPPFLAGS in src/bin/lttng-sessiond/Makefile.am

or else I got the following when defining the tracepoints:

In file included from udev-monitor.c:37:0:
udev-monitor-provider.h:31:28: fatal error: udev-monitor-provider.h: No such file or directory
#define TRACEPOINT_INCLUDE "./udev-monitor-provider.h"
^_~~~~~~~~~~~~~~~~~~~~~~

Maybe I shouldn't do that?

Anyway, even if I do as you say, this is not the end of it. It still ends up being included more than once from another path:

In file included from /usr/local/include/lttng/ust-tracepoint-event.h:27:0,
from /usr/local/include/lttng/tracepoint-event.h:58,
from udev-monitor-provider.h:67,
from udev-monitor.c:37:
/usr/local/include/lttng/ust-events.h:252:8: error: redefinition of ‘struct lttng_event_field’
struct lttng_event_field {
^_~~~~~~~~~~~~~~
In file included from ../../../include/lttng/channel.h:22:0,
from ../../../include/lttng/lttng.h:29,
from ../../../src/common/sessiond-comm/sessiond-comm.h:29,
from lttng-sessiond.h:25,
from udev-monitor.c:26:
../../../include/lttng/event.h:283:8: note: originally defined here
struct lttng_event_field {

I think I'm doomed to either rename everything, or just forget about UST tracepoints in tools :(