[lttng-dev] LTTng-modules with RT kernel

[lttng-dev] LTTng-modules with RT kernel

[Gaylord Charles]

Hello,

I am currently testing LTTng latest versions with a PREEMPT_RT kernel
(4.6.7-rt12). I've got:
 - LTTng-modules 2.8.3
 - LTTng-tools 2.8.2
 - LTTng-UST 2.8.1

When calling "lttng create", the following message appears:
     Cannot add context lttng_add_preemptible_to_ctx
     Cannot add context lttng_add_migratable_to_ctx

A quick look at the source code (lttng-context.c) makes me wonder if there
could be a bug. The "lttng_add_preemptible_to_ctx" function returns 0, so
if my understanding is correct, there is no problem.
Do I miss something ?

Regards.
Gaylord
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[lttng-dev] LTTng-modules with RT kernel

[Mathieu Desnoyers]

----- On Oct 24, 2016, at 11:23 AM, Gaylord Charles <gaylord.charles at veo-labs.com> wrote: 

> Hello,

> I am currently testing LTTng latest versions with a PREEMPT_RT kernel
> (4.6.7-rt12). I've got:
> - LTTng-modules 2.8.3
> - LTTng-tools 2.8.2
> - LTTng-UST 2.8.1

> When calling "lttng create", the following message appears:
> Cannot add context lttng_add_preemptible_to_ctx
> Cannot add context lttng_add_migratable_to_ctx

> A quick look at the source code (lttng-context.c) makes me wonder if there could
> be a bug. The "lttng_add_preemptible_to_ctx" function returns 0, so if my
> understanding is correct, there is no problem.
> Do I miss something ?

Fix pushed into master, stable-2.9, and stable-2.8 of lttng-modules: 

commit d0e59d6f099f4663cc62bffb59d960cd4235064f 
Author: Mathieu Desnoyers <mathieu.desnoyers at efficios.com> 
Date: Mon Oct 24 13:27:01 2016 -0400 

Fix: preemptible and migratable context error handling 

When built against preempt-rt and preempt kernels, the "return 0" case 
means success, but lttng-modules incorrectly prints an error in the 
kernel log. 

Given that we handle the -ENOSYS error in lttng_context_init, there is 
no need to keep the ifdefs in that function. 

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com> 

Thanks for reporting! 

Mathieu 

> Regards.
> Gaylord

> _______________________________________________
> lttng-dev mailing list
> lttng-dev at lists.lttng.org
> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev

-- 
Mathieu Desnoyers 
EfficiOS Inc. 
http://www.efficios.com 
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