[lttng-dev] [PATCH] Fix: Rename kvm TRACE_SYSTEM to avoid name clash

[Francis Giraldeau]

Le jeu. 16 juil. 2015 à 12:41, Mathieu Desnoyers <
mathieu.desnoyers at efficios.com> a écrit :

> I cannot reproduce this issue with a kernel 4.1.1 and with
> lttng-modules master and stable-2.6 HEAD.
>
> Can you double-check ?
>

Thanks for this follow-up. I confirm that the bug is reproducible with
lttng-modules master on linux 4.1. I opened an issue in the bug tracker for
further details. I added a script to reproduce the bug easily.

https://bugs.lttng.org/issues/895


> Moreover, just changing the TRACE_SYSTEM without changing
> the tracepoint namespacing prefix from kvm_ to kvm_x86 in the
> whole file is wrong.


I do not understand. In lttng-ust, there is a TRACEPOINT_PROVIDER string
that must be repeated into each TRACEPOINT_EVENT declaration, but this is
not the case for the kernel LTTNG_TRACEPOINT_EVENT macro. Can you explain
what you mean by "namespace"?


> And if we do this, we would need the _MAP
> flavor of the macros to map to the original kernel names.
>

In fact, event names are not modified by the patch, such that backward
compatibility seems preserved AFAIK. Do I miss something?

Francis


> ----- On Jul 14, 2015, at 2:43 PM, Francis Giraldeau
> francis.giraldeau at gmail.com wrote:
>
> > From: Cédric Biancheri <cedric.biancheri at polymtl.ca>
> >
> > The lttng-probe-kvm and lttng-probe-kvm-x86 had the same TRACE_SYSTEM
> string.
> > Because of that, both modules can't be loaded at the same time. The
> second
> > module fails to load silently. This patch rename the TRACE_SYSTEM of
> > lttng-probe-kvm-x86 to avoid the clash.
> >
> > Signed-off-by: Francis Giraldeau <francis.giraldeau at gmail.com>
> > ---
> > instrumentation/events/lttng-module/arch/x86/kvm/trace.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/instrumentation/events/lttng-module/arch/x86/kvm/trace.h
> > b/instrumentation/events/lttng-module/arch/x86/kvm/trace.h
> > index 32c4743..ddbfda7 100644
> > --- a/instrumentation/events/lttng-module/arch/x86/kvm/trace.h
> > +++ b/instrumentation/events/lttng-module/arch/x86/kvm/trace.h
> > @@ -12,7 +12,7 @@
> > #include <../arch/x86/kvm/kvm_cache_regs.h>
> >
> > #undef TRACE_SYSTEM
> > -#define TRACE_SYSTEM kvm
> > +#define TRACE_SYSTEM kvm_x86
> >
> > /*
> >  * Tracepoint for guest mode entry.
> > --
> > 2.1.4
> >
> >
> > _______________________________________________
> > lttng-dev mailing list
> > lttng-dev at lists.lttng.org
> > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
>
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com
>
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