[lttng-dev] Error in lttng-modules after pulling in commit 'writeback: Fix sync livelock due to b_dirty_time processing'

Tue Oct 20 22:34:05 EDT 2020

Thanks for the information.

I have pulled in all commits up till v4.14.200, not some random commit, I have mentioned the commit ID in the mail for reference because of which I was facing the error.

Is there something you can help me with?

From: Mathieu Desnoyers [mailto:mathieu.desnoyers at efficios.com]
Sent: 20 October 2020 20:04
To: Naaz, Syeda Shagufta <SyedaShagufta_Naaz at mentor.com>
Cc: lttng-dev <lttng-dev at lists.lttng.org>
Subject: Re: [lttng-dev] Error in lttng-modules after pulling in commit 'writeback: Fix sync livelock due to b_dirty_time processing'

----- On Oct 20, 2020, at 2:59 AM, lttng-dev <lttng-dev at lists.lttng.org<mailto:lttng-dev at lists.lttng.org>> wrote:

Hi All,

I’m facing compilation error in build after pulling in the stable kernel LTS(4.14.y) commit - https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.14.y&id=77322edb99f0176ec67a300b9f263719ba391b89

Hi,

lttng-modules tracks the stable kernels through their versions (e.g. 4.14.165). There are ifdefs in the
lttng-modules code to choose the right instrumentation implementation based on the kernel version it is
built against.

Of course, if you don't follow the versioning scheme of the stable kernels and cherry-pick random commits,
there is little lttng-modules can do to track those changes. We have worked with Ubuntu, Redhat and Debian
distributions to ensure their kernels are versioned in a way which is also detected by lttng-modules, in the
situations where the kernels diverge from upstream. If you want to create your own kernel which also
differs from all other existing kernels out there, you will also need to take care of versioning it and adapt
lttng-modules accordingly.

Thanks,

Mathieu

I tried this solution - https://github.com/lttng/lttng-modules/commit/7318a1e88c8097733f5a05529069e4e03c142cae

But this also didn’t resolve my problem.
| In file included from /home/snaaz/elm/8up/main/build_zcu/tmp/work/zcu102_zynqmp_mel-mel-linux/lttng-modules/2.10.9-r0/lttng-modules-2.10.9/probes/../probes/define_trace.h💯0,
|                  from /home/snaaz/elm/8up/main/build_zcu/tmp/work/zcu102_zynqmp_mel-mel-linux/lttng-modules/2.10.9-r0/lttng-modules-2.10.9/probes/../instrumentation/events/lttng-module/writeback.h:735,
|                  from /home/snaaz/elm/8up/main/build_zcu/tmp/work/zcu102_zynqmp_mel-mel-linux/lttng-modules/2.10.9-r0/lttng-modules-2.10.9/probes/lttng-probe-writeback.c:51:
| /home/snaaz/elm/8up/main/build_zcu/tmp/work/zcu102_zynqmp_mel-mel-linux/lttng-modules/2.10.9-r0/lttng-modules-2.10.9/probes/../probes/lttng-tracepoint-event-impl.h:143:6: error: conflicting types for 'trace_writeback_queue_io'
|  void trace_##_name(_proto);
|       ^
| /home/snaaz/elm/8up/main/build_zcu/tmp/work/zcu102_zynqmp_mel-mel-linux/lttng-modules/2.10.9-r0/lttng-modules-2.10.9/probes/../probes/lttng-tracepoint-event-impl.h:55:2: note: in expansion of macro 'LTTNG_TRACEPOINT_EVENT_INSTANCE_MAP'
|   LTTNG_TRACEPOINT_EVENT_INSTANCE_MAP(map, name, map, PARAMS(proto), PARAMS(args))
|   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| /home/snaaz/elm/8up/main/build_zcu/tmp/work/zcu102_zynqmp_mel-mel-linux/lttng-modules/2.10.9-r0/lttng-modules-2.10.9/probes/../probes/lttng-tracepoint-event-impl.h:97:2: note: in expansion of macro 'LTTNG_TRACEPOINT_EVENT_MAP'
|   LTTNG_TRACEPOINT_EVENT_MAP(name, name,    \
|   ^~~~~~~~~~~~~~~~~~~~~~~~~~
| /home/snaaz/elm/8up/main/build_zcu/tmp/work/zcu102_zynqmp_mel-mel-linux/lttng-modules/2.10.9-r0/lttng-modules-2.10.9/probes/../instrumentation/events/lttng-module/writeback.h:375:1: note: in expansion of macro 'LTTNG_TRACEPOINT_EVENT'
|  LTTNG_TRACEPOINT_EVENT(writeback_queue_io,
|  ^~~~~~~~~~~~~~~~~~~~~~
| In file included from /home/snaaz/elm/8up/main/build_zcu/tmp/work-shared/zcu102-zynqmp-mel/kernel-source/include/trace/events/writeback.h:8:0,
|                  from /home/snaaz/elm/8up/main/build_zcu/tmp/work/zcu102_zynqmp_mel-mel-linux/lttng-modules/2.10.9-r0/lttng-modules-2.10.9/probes/lttng-probe-writeback.c:33:
| /home/snaaz/elm/8up/main/build_zcu/tmp/work-shared/zcu102-zynqmp-mel/kernel-source/include/linux/tracepoint.h:187:21: note: previous definition of 'trace_writeback_queue_io' was here
|   static inline void trace_##name(proto)    \
|                      ^
| /home/snaaz/elm/8up/main/build_zcu/tmp/work-shared/zcu102-zynqmp-mel/kernel-source/include/linux/tracepoint.h:352:2: note: in expansion of macro '__DECLARE_TRACE'
|   __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),  \
|   ^~~~~~~~~~~~~~~
| /home/snaaz/elm/8up/main/build_zcu/tmp/work-shared/zcu102-zynqmp-mel/kernel-source/include/linux/tracepoint.h:488:2: note: in expansion of macro 'DECLARE_TRACE'
|   DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
|   ^~~~~~~~~~~~~
| /home/snaaz/elm/8up/main/build_zcu/tmp/work-shared/zcu102-zynqmp-mel/kernel-source/include/trace/events/writeback.h:361:1: note: in expansion of macro 'TRACE_EVENT'
|  TRACE_EVENT(writeback_queue_io,

Kindly look into it and do the needful. Thanks!

Regards,
Syeda Shagufta Naaz
Software Development Engineer | Mentor Embedded Linux
Mentor,A Siemens Business

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