LTTng bugs repository: Issueshttps://bugs.lttng.org/https://bugs.lttng.org/themes/lttng/favicon/a.ico?14249722912023-12-19T20:03:54ZLTTng bugs repository
Redmine LTTng-tools - Bug #1407 (New): Hang when stopping a live session with a low live valuehttps://bugs.lttng.org/issues/14072023-12-19T20:03:54ZKienan Stewart
<p>While investigating <a class="issue tracker-1 status-5 priority-4 priority-default closed" title="Bug: Investigate why events are no longer recorded by the live view when `DELAYUS` in `tests/regressio... (Resolved)" href="https://bugs.lttng.org/issues/1403">#1403</a>, I noticed some test runs would intermittently hang when the live delay value was set very low (eg. 1us).</p>
<p>For example, in <code>tests/regression/tools/clear/test_ust</code> the test <code>test_ust_streaming_live</code> would hang executing <code>lttng stop sessionX</code>. After investigating the issue I noted the following:</p>
<ul>
<li>the lttng client is hanging, pending a response from the sessiond</li>
<li>the consumer's consumer_thread_data_poll thread appear to be looping in <code>consumer_timer_signal_thread_qs</code> while trying to remove the monitor timer during channel deletion: <pre>
Thread 7 (Thread 0x7f999bfff680 (LWP 3060295) "lttng-consumerd"):
#0 sigpending (set=0x7f999bffdea0) at ../sysdeps/unix/sysv/linux/sigpending.c:27
#1 0x00005559299f07ec in consumer_timer_signal_thread_qs (signr=47) at consumer/consumer-timer.cpp:325
#2 consumer_channel_timer_stop (timer_id=timer_id@entry=0x7f998c0021c0, signal=47) at consumer/consumer-timer.cpp:422
#3 0x00005559299f122f in consumer_timer_monitor_stop (channel=channel@entry=0x7f998c000f40) at consumer/consumer-timer.cpp:531
#4 0x00005559299dabbf in consumer_del_channel (channel=channel@entry=0x7f998c000f40) at consumer/consumer.cpp:379
#5 0x00005559299ee83a in consumer_stream_destroy (stream=stream@entry=0x7f998c01a830, ht=<optimized out>) at consumer/consumer-stream.cpp:1070
#6 0x00005559299e3c61 in consumer_del_stream (ht=<optimized out>, stream=0x7f998c01a830) at consumer/consumer.cpp:547
#7 consumer_thread_data_poll (data=0x55592b498ba0) at consumer/consumer.cpp:2747
#8 0x00007f99aaaa63ec in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:444
#9 0x00007f99aab26a5c in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81
</pre></li>
<li>the consumerd's consumer_timer_thread was often handling the live timer: <pre>
Thread 4 (Thread 0x7f99a991b680 (LWP 3060292) "lttng-consumerd"):
#0 __GI___libc_write (nbytes=124, buf=0x7f99a9919e90, fd=2) at ../sysdeps/unix/sysv/linux/write.c:26
#1 __GI___libc_write (fd=2, buf=0x7f99a9919e90, nbytes=124) at ../sysdeps/unix/sysv/linux/write.c:24
#2 0x00007f99aaa9dbb5 in _IO_new_file_write (f=0x7f99aabf26a0 <_IO_2_1_stderr_>, data=0x7f99a9919e90, n=124) at ./libio/fileops.c:1180
#3 0x00007f99aaa9cf70 in new_do_write (fp=fp@entry=0x7f99aabf26a0 <_IO_2_1_stderr_>, data=data@entry=0x7f99a9919e9
0 "DBG1 - 10:31:33.730698608 [3060287/3060292]: Live timer for channel 17 (in live_timer() at consumer/consumer-timer.cpp:284)\n", to_do=to_do@entry=124) at ./libio/libioP.h:946
#4 0x00007f99aaa9e2a1 in _IO_new_file_xsputn (n=124, data=<optimized out>, f=0x7f99aabf26a0 <_IO_2_1_stderr_>) at ./libio/fileops.c:1254
#5 _IO_new_file_xsputn (f=0x7f99aabf26a0 <_IO_2_1_stderr_>, data=<optimized out>, n=124) at ./libio/fileops.c:1196
#6 0x00007f99aaa71409 in __printf_buffer_flush_to_file (buf=buf@entry=0x7f99a9919e60) at ../libio/libioP.h:946
#7 0x00007f99aaa714c0 in __printf_buffer_to_file_done (buf=buf@entry=0x7f99a9919e60) at ./stdio-common/printf_buffer_to_file.c:120
#8 0x00007f99aaa7ac0d in __vfprintf_internal (s=0x7f99aabf26a0 <_IO_2_1_stderr_>, format=0x555929a57cd8 "DBG1 - %s [%s]: Live timer for channel %lu (in %s() at consumer/consumer-timer.cpp:284)\n", ap=ap@entry=0x7f99a9919f60, mode_
flags=mode_flags@entry=0) at ./stdio-common/vfprintf-internal.c:1475
#9 0x00007f99aaa70296 in __fprintf (stream=<optimized out>, format=<optimized out>) at ./stdio-common/fprintf.c:32
#10 0x00005559299f2280 in live_timer (si=0x7f99a991a160, ctx=0x55592b498ba0) at consumer/consumer-timer.cpp:284
#11 consumer_timer_thread (data=0x55592b498ba0) at consumer/consumer-timer.cpp:789
#12 0x00007f99aaaa63ec in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:444
#13 0x00007f99aab26a5c in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81
</pre></li>
</ul>
<p><code>consumer_timer_signal_thread_qs</code> is busy loop until the the the signal in question is no longer pending. In <code>consumer-timer.cpp::consumer_timer_thread</code>, the signals are waited on by <code>sigwaitinfo</code>, and there are some ordering rules (see man 7 signal):</p>
<ul>
<li>for RT signals, by signal priority</li>
<li>for standard signals, an unspecified order</li>
<li>in Linux standard signals are delivered before RT signals</li>
</ul>
<p>The signal priorities are their signal number as defined [[<a class="external" href="https://github.com/lttng/lttng-tools/blob/dff46b736afb7945aaf635de661b920dd0d01d7f/src/common/consumer/consumer-timer.hpp#L17|here">https://github.com/lttng/lttng-tools/blob/dff46b736afb7945aaf635de661b920dd0d01d7f/src/common/consumer/consumer-timer.hpp#L17|here</a>]]. Lower values have a higher priority.</p>
<p>When the live session is configured with a low delay, eg <code>--live=1</code>, the live timer is firing relatively rapidly and can prevent the signal fired by the monitor timer from being handled. This in turn means that the session destruction may hang until (hopefully) the monitor signal is handled and no longer pending.</p>
<p>A few options were discussed:</p>
<ul>
<li>changing signal ordering (eg. reducing the priority of live signal): while it would address this particular case, it then means a session with a low value for the monitor timer could equally starve out the handling of the live timer's signal</li>
<li>using <code>sigpending</code> in combination with <code>sigwaitinfo</code>: while it's possible to get all pending signals as a set, it seems to not be possible to retrieve the details (<code>siginfo_t</code>) which are required some some data (eg. pointers) to properly handle the signal</li>
<li>signalfd: very linux specific</li>
<li>timer_fd: very linux specific</li>
<li>custom scheduler: eg., <a class="external" href="https://github.com/nsec/badge-conf-2023/blob/nsec2023/lib/scheduling/scheduler.hpp">https://github.com/nsec/badge-conf-2023/blob/nsec2023/lib/scheduling/scheduler.hpp</a></li>
<li>switch from using channel pointers in the <code>sigval_ptr</code> to passing IDs that can be used for lookups which may fail gracefully instead; that way the pending signals wouldn't have to all be cleared in <code>consumer_timer_signal_thread_qs</code></li>
</ul>
<p>It seems the most promising path is to implement a small deadline scheduler.</p> LTTng-tools - Bug #1402 (New): Some files are missing REUSE licensing and copyright informationhttps://bugs.lttng.org/issues/14022023-11-14T15:03:06ZPhilippe Proulxeeppeliteloop@gmail.com
<p>Running <code>reuse lint</code> at the root of the source tree reveals many files are missing copyright and/or license information (SPDX):</p>
<blockquote>
<p>Unfortunately, your project is not compliant with version 3.0 of the REUSE Specification :-(</p>
</blockquote>
<p>This includes pretty much all the <code>Makefile.am</code> and <code>*.m4</code> files as well as <code>src/vendor/fmt/*</code>, <code>src/vendor/msgpack/*</code>, and <code>src/vendor/optional.hpp</code>.</p>
<p>Note that to keep vendor files unmodified, you may use the <code>.license</code> or <code>.reuse/dep5</code> <a href="https://reuse.software/spec/" class="external">strategies</a>.</p> LTTng-tools - Bug #1400 (New): Completion of error handlinghttps://bugs.lttng.org/issues/14002023-10-26T20:33:03ZMarkus Elfring
<p>I have looked at a few source files for your current software.<br />I have noticed that some checks for return codes are missing.</p>
Would you like to add more error handling for return values from functions like the following?
<ul>
<li>fprintf ⇒ usage<br /> <a class="external" href="https://github.com/lttng/lttng-tools/blob/d4333eb996dec315fb721074c2cf49adee04363b/src/bin/lttng-consumerd/lttng-consumerd.cpp#L159-L200">https://github.com/lttng/lttng-tools/blob/d4333eb996dec315fb721074c2cf49adee04363b/src/bin/lttng-consumerd/lttng-consumerd.cpp#L159-L200</a></li>
<li>pthread_mutex_lock ⇒ lttng_thread_create<br /> <a class="external" href="https://github.com/lttng/lttng-tools/blob/d4333eb996dec315fb721074c2cf49adee04363b/src/bin/lttng-sessiond/thread.cpp#L98">https://github.com/lttng/lttng-tools/blob/d4333eb996dec315fb721074c2cf49adee04363b/src/bin/lttng-sessiond/thread.cpp#L98</a></li>
</ul> LTTng-tools - Bug #1399 (New): reserved identifier violationhttps://bugs.lttng.org/issues/13992023-10-26T20:02:18ZMarkus Elfring
<p>I would like to point out that some identifiers do eventually not fit to the expected naming convention of the C++ language standard.<br /><a class="external" href="https://wiki.sei.cmu.edu/confluence/display/cplusplus/DCL51-CPP.+Do+not+declare+or+define+a+reserved+identifier">https://wiki.sei.cmu.edu/confluence/display/cplusplus/DCL51-CPP.+Do+not+declare+or+define+a+reserved+identifier</a></p>
<p>Would you like to adjust your selection for unique names?</p>
Examples:
<ul>
<li>_LTTNG_BUG_H<br /> <a class="external" href="https://github.com/lttng/lttng-tools/blob/d4333eb996dec315fb721074c2cf49adee04363b/src/common/bug.hpp#L8-L9">https://github.com/lttng/lttng-tools/blob/d4333eb996dec315fb721074c2cf49adee04363b/src/common/bug.hpp#L8-L9</a></li>
<li>_LTT_UTILS_H<br /> <a class="external" href="https://github.com/lttng/lttng-tools/blob/d4333eb996dec315fb721074c2cf49adee04363b/src/bin/lttng-sessiond/utils.hpp#L8-L9">https://github.com/lttng/lttng-tools/blob/d4333eb996dec315fb721074c2cf49adee04363b/src/bin/lttng-sessiond/utils.hpp#L8-L9</a></li>
</ul> LTTng-UST - Bug #1398 (New): reserved identifier violationhttps://bugs.lttng.org/issues/13982023-10-26T19:32:57ZMarkus Elfring
<p>I would like to point out that some identifiers do eventually not fit to the expected naming convention of the C language standard.<br /><a class="external" href="https://www.securecoding.cert.org/confluence/display/c/DCL37-C.+Do+not+declare+or+define+a+reserved+identifier">https://www.securecoding.cert.org/confluence/display/c/DCL37-C.+Do+not+declare+or+define+a+reserved+identifier</a></p>
<p>Would you like to adjust your selection for unique names?</p>
Examples:
<ul>
<li>_UST_COMMON_CLOCK_H<br /> <a class="external" href="https://github.com/lttng/lttng-ust/blob/8bc1125eb851b2c52d3263c2992e6806017e98e7/src/common/clock.h#L7-L8">https://github.com/lttng/lttng-ust/blob/8bc1125eb851b2c52d3263c2992e6806017e98e7/src/common/clock.h#L7-L8</a></li>
<li>__lttng_ust_siov<br /> <a class="external" href="https://github.com/lttng/lttng-ust/blob/8bc1125eb851b2c52d3263c2992e6806017e98e7/src/common/snprintf/fvwrite.h#L18">https://github.com/lttng/lttng-ust/blob/8bc1125eb851b2c52d3263c2992e6806017e98e7/src/common/snprintf/fvwrite.h#L18</a></li>
</ul> Babeltrace - Bug #1397 (New): reserved identifier violationhttps://bugs.lttng.org/issues/13972023-10-26T18:56:27ZMarkus Elfring
<p>I would like to point out that a few identifiers do eventually not fit to the expected naming convention of the C language standard.<br /><a class="external" href="https://www.securecoding.cert.org/confluence/display/c/DCL37-C.+Do+not+declare+or+define+a+reserved+identifier">https://www.securecoding.cert.org/confluence/display/c/DCL37-C.+Do+not+declare+or+define+a+reserved+identifier</a></p>
<p>Would you like to adjust your selection for unique names?</p>
Examples:
<ul>
<li>__BT_IN_BABELTRACE_H<br /> <a class="external" href="https://github.com/efficios/babeltrace/blob/8a87cdbd41e2e04b1b64e9959751cdabe72281c1/include/babeltrace2/babeltrace.h#L13-L17">https://github.com/efficios/babeltrace/blob/8a87cdbd41e2e04b1b64e9959751cdabe72281c1/include/babeltrace2/babeltrace.h#L13-L17</a></li>
<li>_BABELTRACE_UTC_H<br /> <a class="external" href="https://github.com/efficios/babeltrace/blob/8a87cdbd41e2e04b1b64e9959751cdabe72281c1/src/compat/utc.h#L7-L8">https://github.com/efficios/babeltrace/blob/8a87cdbd41e2e04b1b64e9959751cdabe72281c1/src/compat/utc.h#L7-L8</a></li>
</ul> Userspace RCU - Bug #1396 (New): reserved identifier violationhttps://bugs.lttng.org/issues/13962023-10-26T15:17:27ZMarkus Elfring
<p>I would like to point out that a few identifiers do eventually not fit to the expected naming convention of the C language standard.<br /><a class="external" href="https://www.securecoding.cert.org/confluence/display/c/DCL37-C.+Do+not+declare+or+define+a+reserved+identifier">https://www.securecoding.cert.org/confluence/display/c/DCL37-C.+Do+not+declare+or+define+a+reserved+identifier</a></p>
<p>Would you like to adjust your selection for unique names?</p>
Examples:
<ul>
<li>_URCU_WAIT_H<br /> <a class="external" href="https://github.com/urcu/userspace-rcu/blob/008a71ef213f23c8d403e086563155121b286c0c/src/urcu-wait.h#L5">https://github.com/urcu/userspace-rcu/blob/008a71ef213f23c8d403e086563155121b286c0c/src/urcu-wait.h#L5</a></li>
<li>__cds_wfcq_init<br /> <a class="external" href="https://github.com/urcu/userspace-rcu/blob/008a71ef213f23c8d403e086563155121b286c0c/include/urcu/wfcqueue.h#L136">https://github.com/urcu/userspace-rcu/blob/008a71ef213f23c8d403e086563155121b286c0c/include/urcu/wfcqueue.h#L136</a></li>
</ul> Babeltrace - Bug #1389 (New): src.ctf.fs crash with invalid tracehttps://bugs.lttng.org/issues/13892023-09-18T20:16:39ZSimon Marchisimon.marchi@polymtl.ca
<p>Using the attached trace, I get:</p>
<pre>
$ ./src/cli/babeltrace2 trace
09-18 16:15:58.978 335803 335803 E PLUGIN/CTF/MSG-ITER ctf_msg_iter_get_next_message@msg-iter.cpp:2715 [auto-disc-source-ctf-fs] Cannot handle state: msg-it-addr=0x613000000580, state=DSCOPE_EVENT_PAYLOAD_CONTINUE
09-18 16:15:58.978 335803 335803 F LIB/ASSERT-COND bt_lib_assert_cond_failed@assert-cond.c:63 Babeltrace 2 library postcondition not satisfied.
09-18 16:15:58.978 335803 335803 F LIB/ASSERT-COND bt_lib_assert_cond_failed@assert-cond.c:65 ------------------------------------------------------------------------
09-18 16:15:58.978 335803 335803 F LIB/ASSERT-COND bt_lib_assert_cond_failed@assert-cond.c:66 Condition ID: `post:message-iterator-class-next-method:no-error-if-no-error-status`.
09-18 16:15:58.978 335803 335803 F LIB/ASSERT-COND bt_lib_assert_cond_failed@assert-cond.c:68 Function: bt_message_iterator_class_next_method().
09-18 16:15:58.978 335803 335803 F LIB/ASSERT-COND bt_lib_assert_cond_failed@assert-cond.c:69 ------------------------------------------------------------------------
09-18 16:15:58.978 335803 335803 F LIB/ASSERT-COND bt_lib_assert_cond_failed@assert-cond.c:70 Error is:
09-18 16:15:58.978 335803 335803 F LIB/ASSERT-COND bt_lib_assert_cond_failed@assert-cond.c:72 Current thread has an error, but user function returned a non-error status: status=OK
09-18 16:15:58.978 335803 335803 F LIB/ASSERT-COND bt_lib_assert_cond_failed@assert-cond.c:75 Aborting...
</pre> Babeltrace - Bug #1374 (New): Babeltrace fails to read trace with no data stream type ID when the...https://bugs.lttng.org/issues/13742023-04-26T17:57:32ZErica Bugden
<p>Babeltrace is not able to read a trace that does not contain data stream IDs (empty packet header) when the metadata specifies an ID for the stream. Trace Compass is also unable to read this trace. If the lines mentioning the stream ID are removed from the metadata, then babeltrace is able to read the trace.</p>
<a name="Does-this-need-to-be-fixed"></a>
<h3 >Does this need to be fixed?<a href="#Does-this-need-to-be-fixed" class="wiki-anchor">¶</a></h3>
<p>This was first reported as a barectf issue <a class="external" href="https://github.com/efficios/barectf/issues/28">https://github.com/efficios/barectf/issues/28</a> , but after further consideration the issue appears to be in a grey area in the CTF 1.8 specification. Whether it is the CTF generator's (barectf) responsibility or the CTF reader's responsibility is up for debate.</p>
<p>The superfluous metadata information need not prevent the trace from being parsed. For example, yactfr <a class="external" href="https://github.com/eepp/yactfr">https://github.com/eepp/yactfr</a> is able to read the trace. However, considering that:</p>
<ul>
<li>At least two CTF readers (babeltrace and Trace Compass) cannot read the trace, and</li>
<li>It is easy to fix in barectf (Proposed fix: <a class="external" href="https://review.lttng.org/c/barectf/+/9868">https://review.lttng.org/c/barectf/+/9868</a> )</li>
</ul>
<p>this is not a high priority issue in babeltrace.</p>
<a name="Context"></a>
<h1 >Context<a href="#Context" class="wiki-anchor">¶</a></h1>
<p>- Background and reproducer: barectf github issue <a class="external" href="https://github.com/efficios/barectf/issues/28">https://github.com/efficios/barectf/issues/28</a> <br />- Background and specification discussion: barectf fix <a class="external" href="https://review.lttng.org/c/barectf/+/9868">https://review.lttng.org/c/barectf/+/9868</a></p> LTTng-tools - Bug #1342 (New): Rotation thread's handling of session consumed size notifications ...https://bugs.lttng.org/issues/13422021-12-09T21:40:35ZJérémie Galarneaujeremie.galarneau@efficios.com
<p>Related to this change:<br /><a class="external" href="https://review.lttng.org/c/lttng-tools/+/6886/">https://review.lttng.org/c/lttng-tools/+/6886/</a></p>
The race described in that change has another consequence: the notification could refer to a different session instance of the same name:
<ul>
<li>notification emitted for session <code>foo</code>,</li>
<li>session <code>foo</code> is destroyed,</li>
<li>a new session named <code>foo</code> is created,</li>
<li>a rotation is triggered for <code>foo</code>.</li>
</ul>
There are multiple solutions for this:
<ul>
<li>Provide a unique session id as part the of the evaluation of <code>SESSION_CONSUMED_SIZE</code>,</li>
<li>Register an internal trigger that has the <code>rotate session</code> action (since ids are sampled during their handling).</li>
</ul>
<p>I can't work on a fix right now, but here is a placeholder patch that will eventually contain the fix:<br /><a class="external" href="https://review.lttng.org/c/lttng-tools/+/6907">https://review.lttng.org/c/lttng-tools/+/6907</a></p>
<p>This is hypothetical and I noticed it during a code review; nobody reported this problem.</p> LTTng-tools - Bug #1267 (New): odr-violation for config_str_yeshttps://bugs.lttng.org/issues/12672020-05-13T01:16:50ZJonathan Rajotte Julienjonathan.rajotte-julien@efficios.com
<p>Using "clang version 10.0.0-4ubuntu1".</p>
<p>Configure: "./configure CFLAGS="-g -O0 -fsanitize=address"</p>
<p>lttng-sessiond yield:<br /><pre>
=================================================================
==3248430==ERROR: AddressSanitizer: odr-violation (0x000000800e80):
[1] size=8 'config_str_yes' session-config.c:56:20
[2] size=8 'config_str_yes' session-config.c:56:20
These globals were registered at these points:
[1]:
#0 0x43447d in __asan_register_globals (/home/joraj/lttng/master/install/bin/lttng-sessiond+0x43447d)
#1 0x6e6a8b in asan.module_ctor (/home/joraj/lttng/master/install/bin/lttng-sessiond+0x6e6a8b)
[2]:
#0 0x43447d in __asan_register_globals (/home/joraj/lttng/master/install/bin/lttng-sessiond+0x43447d)
#1 0x7eff93c40a6b in asan.module_ctor (/home/joraj/lttng/master//install/lib/liblttng-ctl.so.0+0x144a6b)
==3248430==HINT: if you don't care about these errors you may set ASAN_OPTIONS=detect_odr_violation=0
SUMMARY: AddressSanitizer: odr-violation: global 'config_str_yes' at session-config.c:56:20
==3248430==ABORTING
</pre></p>
<p>The linker does not warn.</p> LTTng-tools - Bug #1262 (New): Metadata channel properties are not configurable (kernel domain)https://bugs.lttng.org/issues/12622020-05-05T22:45:05ZJérémie Galarneaujeremie.galarneau@efficios.com
<p>It is possible to explicitly create a kernel channel named <em>metadata</em> in the kernel domain.</p>
<pre>
$ lttng enable-channel -k metadata --num-subbuf 256
Kernel channel metadata enabled for session youssef_robert
</pre>
<p>This channel can be listed:<br /><pre>
- metadata: [enabled]
Attributes:
Event-loss mode: discard
Sub-buffer size: 1048576 bytes
Sub-buffer count: 256
Switch timer: inactive
Read timer: 200000 µs
Monitor timer: 1000000 µs
Blocking timeout: 0 µs
Trace file count: 1 per stream
Trace file size: unlimited
Output mode: splice
Statistics:
Discarded events: 0
Event rules:
None
</pre></p>
<p>It is surprisingly possible to add event rules to such a channel.</p>
<pre>
lttng enable-event -k -a -c metadata
All Kernel events are enabled in channel metadata
</pre>
<p>Predictably, since this channel is not identified as a <em>special</em> metadata channel, the configuration is not used during the <a href="https://github.com/lttng/lttng-tools/blob/ab5be9f/src/bin/lttng-sessiond/kernel-consumer.c#L203" class="external">creation of the metadata stream</a>.</p>
<p>Instead, a <a href="https://github.com/lttng/lttng-tools/blob/ab5be9fa2eb5ba9600a82cd18fd3cfcbac69169a/src/bin/lttng-sessiond/trace-kernel.h#L100" class="external">dedicated ltt_kernel_metadata</a> field is used. This field is initialized during the creation of the kernel session with a set of default attributes.</p>
<p>It is unclear to me if this ever worked since I couldn't find a trace of the code that should handle this.</p> LTTng-tools - Bug #1256 (New): Check babeltrace1 stderr output in testshttps://bugs.lttng.org/issues/12562020-04-08T19:23:18ZMathieu Desnoyersmathieu.desnoyers@efficios.com
<p>Currently, babeltrace1 stderr's output contains warnings which are not checked by the tests. Those do not fail the overall babeltrace execution, but end up being unexpected regressions when they appear between releases.</p>
<p>We could modify all babeltrace invocations to add a helper which saves the stderr output, and check that it is empty after babeltrace has completed execution. If non-empty, a test error would be reported.</p> LTTng-tools - Bug #1211 (New): Can't quit lttng-sessiond with ctrl-c when built with --disable-epollhttps://bugs.lttng.org/issues/12112019-11-28T21:59:44ZSimon Marchisimon.marchi@polymtl.ca
<p>Step 1: configure lttng-tools with <code>./configure --disable-epoll</code><br />Step 2: launch lttng-sessiond<br />Step 3: try to stop it with ctrl-c</p>
<p>It should quit, but it doesn't quit.</p>
<p>My thorough investigation has shown that the "client management" thread stays in an infinite loop in compat_poll_wait.</p> LTTng-tools - Bug #1072 (New): configure does not check for needed Libxml2 symbolshttps://bugs.lttng.org/issues/10722016-11-01T09:09:00ZPhilippe Proulxeeppeliteloop@gmail.com
<p>LTTng-tools's <code>configure</code> script checks for the existence and version of Libxml2 with pkg-config, but it does not check for the exact needed symbols. Libxml2 has a lot of <code>--with-</code> configuration options, some of which can disable modules that LTTng-tools needs.</p>
<p>I suggest that we check one selected symbol per module. This should ensure that at least the module exists, which should guarantee that the other symbols are available too.</p>
<p>It looks like the following Libxml2 configuration options enable the needed modules:</p>
<pre>
--with-minimum --with-sax1 --with-tree --with-writer --with-schemas
</pre>
<ul>
<li><code>--with-minimum</code> simply "resets" the enabled modules to none.</li>
<li><code>--with-sax1</code> is needed for basic XML parsing (load).</li>
<li><code>--with-tree</code> is needed for querying an XML document as a tree (load).</li>
<li><code>--with-writer</code> is needed for writing XML (save, MI).</li>
<li><code>--with-schemas</code> is needed for XML validation (load).</li>
</ul>
<p>All those options are available in the Libxml2 2.7.6 release (minimum required version by LTTng-tools).</p>