Add parameter -f to rm in Makefile clean target

If the files we want to delete do not exist (for example after a failed
build), the make clean fails.

Signed-off-by: Simon Marchi <simon.marchi@polymtl.ca>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix: missing dependency for liblttng-ust-tracepoint.so

Fixes #538

Reported-by: Alexandros Frantzis <alexandros.frantzis@canonical.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Remove 0.x TODO

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

Add warning about default prefix and library paths to README

Fixes #467

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Revert "Revert "Fix (another) linker library order""

This reverts commit a5b31eab4e1f190d68d51c47dabb60b64ee471e7.

The patch was OK in the first place. Explanation:

* Simon Marchi <simon.marchi@polymtl.ca> wrote:

Actually, $^ here is "demo.o", not "demo. Also, the libs should appear
after the objects on the command line. See the "-l" section in
http://gcc.gnu.org/onlinedocs/gcc/Link-Options.html. On most setup
this doesn't matter, since -Wl,--no-as-needed was the default pretty
much everywhere. Ubuntu decided to use -Wl,--as-needed to avoid
unnecessary dependencies, so the order becomes important. If you try
to manual build on a recent Ubuntu you will get undefined references
to dlopen and such. So this patch is good.

If you read carefully the log sent by Alexandre, you see that it is
when building the shared libs in this directory
(lttng-ust-provider-ust-tests-demo.so) that the build fails. I don't
know why it fails, but Alexandre hinted that passing "-fPIE -pie" to
build a shared library is weird (it is usually -fPIC -pic). I am not
sure where that comes from. This behaviour only happens when building
the package, not when building manually.

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

Revert "Revert "Fix linker library order""

This reverts commit 661805af83e2d4e7fa19432d6ae553460d6cd524.

The patch was OK in the first place. Explanation:

* Simon Marchi <simon.marchi@polymtl.ca> wrote:

Actually, $^ here is "demo.o", not "demo. Also, the libs should appear
after the objects on the command line. See the "-l" section in
http://gcc.gnu.org/onlinedocs/gcc/Link-Options.html. On most setup
this doesn't matter, since -Wl,--no-as-needed was the default pretty
much everywhere. Ubuntu decided to use -Wl,--as-needed to avoid
unnecessary dependencies, so the order becomes important. If you try
to manual build on a recent Ubuntu you will get undefined references
to dlopen and such. So this patch is good.

If you read carefully the log sent by Alexandre, you see that it is
when building the shared libs in this directory
(lttng-ust-provider-ust-tests-demo.so) that the build fails. I don't
know why it fails, but Alexandre hinted that passing "-fPIE -pie" to
build a shared library is weird (it is usually -fPIC -pic). I am not
sure where that comes from. This behaviour only happens when building
the package, not when building manually.

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

snprintf: play nice with static checker

Coverity complains that we pass a singleton as an array. Transform it
into an array of size 1.

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

tracepoint.c: Add coverity alloc/free annotations

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

Fix: "fields" leak on register

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

Fix: memory leak for events without fields

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

Fix: memory leak on connection reset

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

Revert "Fix linker library order"

This reverts commit 725e63c5194bfdcde0a2a3507aca156ba36cf49f.

Hrm, actually, these patches are wrong.

commit 725e63c5194bfdcde0a2a3507aca156ba36cf49f for instance:

"Libraries must be specified after the binary target."

 demo: demo.o
-       $(CC) -o $@ $(LIBS) $^
+       $(CC) -o $@ $^ $(LIBS)

the binary target here is "$@".

$^ is the source file name (demo.c).

this patch moves the source file name prior to the libraries, which is
incorrect (ref: gcc(1)). The input files should appear last.

So it breaks builds where $(LIBS) is non-empty.

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

Revert "Fix (another) linker library order"

This reverts commit a51ac6d9a011ba10b0be396dc1e801b2fc829651.

Hrm, actually, these patches are wrong.

commit 725e63c5194bfdcde0a2a3507aca156ba36cf49f for instance:

"Libraries must be specified after the binary target."

 demo: demo.o
-       $(CC) -o $@ $(LIBS) $^
+       $(CC) -o $@ $^ $(LIBS)

the binary target here is "$@".

$^ is the source file name (demo.c).

this patch moves the source file name prior to the libraries, which is
incorrect (ref: gcc(1)). The input files should appear last.

So it breaks builds where $(LIBS) is non-empty.

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

Fix: incorrect support for multi-context

* Zifei Tong <soariez@gmail.com> wrote:
> I did some debugging one this issue. The problem only occurs when we
> have more than one context field.
> So this will not work, too:
>
> lttng create
> lttng enable-event -a -u
> lttng add-context -u -t vpid
> lttng add-context -u -t vtid
> lttng start
> $@
> lttng stop
> sleep 1
> lttng view
> lttng destroy
>
> The problem I found out is wrong `fields` argument passed into
> `ustcomm_register_channel`.
> The `fields` argument passed is a pointer to the `event_field` of the
> first element in a `lttng_ctx_field` array, but not a
> `lttng_event_field` array as expected.

Fixes #529

Reported-by: Francis Giraldeau <francis.giraldeau@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix (another) linker library order

Libraries must be specified after the binary target.

Signed-off-by: Francis Giraldeau <francis.giraldeau@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix typo in run script

The actual library is liblttng-ust-libc-wrapper.so

Signed-off-by: Francis Giraldeau <francis.giraldeau@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix linker library order

Libraries must be specified after the binary target.

Signed-off-by: Francis Giraldeau <francis.giraldeau@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix examples: add missing CPPFLAGS

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

example Makefiles: standardize on $^ for linking

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

Fix demo example Makefile

Missing tp2.c in object file due to incorrect use of $<.

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

Move "hello-static-lib" to doc/examples and add non-automake Makefiles

The examples are now automatically built as part of the default make
target and plain Makefiles with no dependency on automake are provided
for clarity.

Update the manpage and README to reflect the change and remove lots of
trailing whitespace.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Version 2.2.0-rc2

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

manpage: Document probe provider compatibility

Fixes #502

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

Fix: add provider ABI compatibility check

There is not much we can do for this compatibility bug in lttng-ust 2.0
and 2.1 (already stable). Adding this check so that starting with
lttng-ust 2.2, when liblttng-ust encounters a probe provider with a
provider version major number higher than it supports, it will reject
it.

Fixes #502

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

Cleanup: ignore mktemp return value

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

Cleanup: documentation: argument vs field

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

Documentation: document undefined behavior for NULL pointers

Strings, arrays, sequences have undefined behavior if the pointer they
receive are NULL.

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

Cleanup: silence cppcheck error

Not an error per se, but silences:

/home/jenkins/workspace/lttng-ust-cppcheck/liblttng-ust/lttng-ring-buffer-client.h
429 uninitvar error Uninitialized variable: lttng_chan
/home/jenkins/workspace/lttng-ust-cppcheck/liblttng-ust/lttng-ring-buffer-metadata-client.h
197 uninitvar error Uninitialized variable: lttng_chan

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

Fix: add internal mutex for timer

Timer management is not called under ust_lock(). It is only called from
the consumer. Add internal locking for timer start/stop and
synchronization management.

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

32-bit warning fix for cyg profile fast

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

Fix warnings for 32-bit in lttng-ust-cyg-profile

In file included from ../include/lttng/ust-tracepoint-event.h:357,
                 from ../include/lttng/tracepoint-event.h:62,
                 from lttng-ust-cyg-profile.h:63,
                 from lttng-ust-cyg-profile.c:27:
././lttng-ust-cyg-profile.h: In function ‘__event_prepare_filter_stack__lttng_ust_cyg_profile___func_entry’:
././lttng-ust-cyg-profile.h:35: warning: cast from pointer to integer of different size
././lttng-ust-cyg-profile.h:35: warning: cast from pointer to integer of different size
././lttng-ust-cyg-profile.h:35: warning: cast from pointer to integer of different size
././lttng-ust-cyg-profile.h:35: warning: cast from pointer to integer of different size
././lttng-ust-cyg-profile.h: In function ‘__event_prepare_filter_stack__lttng_ust_cyg_profile___func_exit’:
././lttng-ust-cyg-profile.h:46: warning: cast from pointer to integer of different size
././lttng-ust-cyg-profile.h:46: warning: cast from pointer to integer of different size
././lttng-ust-cyg-profile.h:46: warning: cast from pointer to integer of different size
././lttng-ust-cyg-profile.h:46: warning: cast from pointer to integer of different size
  CCLD   liblttng-ust-cyg-profile.la
  CC     lttng-ust-cyg-profile-fast.lo
In file included from ../include/lttng/ust-tracepoint-event.h:357,
                 from ../include/lttng/tracepoint-event.h:62,
                 from lttng-ust-cyg-profile-fast.h:59,
                 from lttng-ust-cyg-profile-fast.c:27:
././lttng-ust-cyg-profile-fast.h: In function ‘__event_prepare_filter_stack__lttng_ust_cyg_profile_fast___func_entry’:
././lttng-ust-cyg-profile-fast.h:35: warning: cast from pointer to integer of different size
././lttng-ust-cyg-profile-fast.h:35: warning: cast from pointer to integer of different size

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

Typo fix in README

Fixes #505

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

Fix: tracepoint.h incorrect assumption about constructor order

Incorrect assumption about constructor execution order can trigger a
segfault when trying to execute tracepoint_register_lib.

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

Cleanup: comment mismatch with code

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

Fix: ABI breakage between 2.1 and 2.2-rc1

Removal of 2 callbacks was causing ABI breakage. This has been caught
in 2.2-rc1.

This was causing the application to segfault when tracing is active.

Fixes #486

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

Documentation: document that sequence len field is unsigned

Fixes #471

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

connect: don't report EACCES

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

connect: don't print error on EPERM

Happens if sessiond is not running, and app is launched.

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

Bump liblttng-ust-ctl lib version major number

This internal library between ust and tools has had its ABI changed
between 2.1 and 2.2.

Fixes #493

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

Optimisation: implement callsite hash table in tracepoint.c

Instead of iterating on every tracepoint callsite each time a probe is
registered/unregistered, use a hash table of callsites to only update
tracepoint sites matching the probe name.

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

Optimisation: only update added library in tracepoint.c

...rather than updating all libraries each time a library is registered.

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

Optimisation: only fix pending events once per lazy update

Suggested-by: Yang Wang <yangw.wang5@unb.ca>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Version 2.2.0-rc1

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

Fix: tracepoint instrumentation constructor order issue

If the linker decides to run a constructor from a tracepoint probe
before the constructor from the application, a recent modification
(commit 558b9d86247004f8e9bbaf8c982f3b2b182093d1) allowed that the wrong
constructor execution order could prohibit the program's tracepoints
from being registered.

Fix this by making two separate constructors.

Fixes #487

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

Documentation: update 2.0 to 2.x

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

Add demo test back as an example

Update the lttng-ust man page to point to doc/examples/demo instead of
the now moved /tests/demo.

Minor typo fix.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Don't rely on explicit context for filtering

Now $ctx can be used without having the contexts explicitly enabled on
the channel.

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

Implement per-context filtering

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

Fix: filter string comparison should check for literal

The prior fix "Fix: filter string wildcard comparison" missed check for
string literal.

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

update tests/demo readme file

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

Add man page for lttng-ust-cyg-profile

[ Edit by Mathieu Desnoyers: minor edits, add reference from
lttng-ust(3) to lttng-ust-cyg-profile(3). ]

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

Fix: filter string wildcard comparison

wildcards * should match 0 or more characters (not 1 or more).

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

Fix: Remove test runner script

Deprecated by the use of Perl prove and test lists.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix: forwarding of call_site argument to field

I ran some tests with the new function entry/exit instrumentations.

The tracepoint provider for lttng_ust_cyg_profile:func_entry and
func_exit does not properly forward the call_site argument to the
call_site field. The patch below fixes the problem.

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

Add demo README

Explain that demo program is moved to lttng-tools.

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

Tests: Use Perl prove as the testsuite runner

Inspired by the test strategy deployed in lttng-tools.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Remove tests depending on consumerd

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Convert hello.cxx test to a build test

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Clean-up of configure.ac and tests/Makefile.am

Removal of disabled tests. Fixes ./configure failing
in distribution package because by missing Makefiles
in tests/ust-basic-tracing and tests/ust-multi-test.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Fix snprintf test and output result to TAP format

Replace the tap library with the one used by babeltrace's test suite which
offers more functionality and outputs in a truly TAP-compliant format.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Replace same_line_marker test with same_line_tracepoint

This new test is up to date and re-enabled strictly as a build test.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Remove tests-libustinstr-malloc

Moved to lttng-tools.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Remove exit-fast test

Moved to lttng-tools.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Remove fork test

Moved to lttng-tools.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Remove daemon test

Moved to lttng-tools.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Remove demo test

Moved to lttng-tools.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Remove outdated test-nevents test

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Remove outdated simple_include test

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Remove outdated register_test test

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Convert hello-static-lib test to a build test

The runtime verification is handled by the "ust/linking" regression test
in lttng-tools.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Convert hello test to a build test only

The runtime verification is handled by the "ust/linking" regression test
in lttng-tools.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Remove outdated libustctl_function_tests test

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Remove outdated test hello2

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Remove outdated dlopen test

Using dlopen to load the tracepoint providers is now discouraged as
specified in the lttng-ust man page.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Remove outdated test basic long

Replaced by the ust-demo test in lttng-tools

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Remove outdated test basic

This test is replaced by the ust-demo test in lttng-tools

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

cyg_profile: implement fast and verbose .so

The "fast" .so (liblttng-ust-cyg-profile-fast.so) is for use-cases where
we expect a complete event stream to be recorded, so we can skip
duplicate information.

The verbose .so (liblttng-ust-cyg-profile.so) is for use-cases where
events discarded are expected, and the trace analyzer needs extra
information to be able to reconstruct the program flow.

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

Performance: add unlikely to tracepoint dynamic linking test

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

Fix: _LGPL_SOURCE rcu dereference fix

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

Implement liblttng-ust-cyg-profile function entry/exit instrumentation

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

Minor fix: libc wrapper internal run script

Take arguments in the script too.

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

Fix: ustctl_recv_register_event pointer mixup

Was causing some event names to appear as "" in metadata.

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

Fix: allow enabling same events for two channels

Fix the following use-case:

  593  lttng create
  594  lttng enable-channel test1 -u
  595  lttng enable-event -u -a
  596  lttng enable-event -u -a -c test1
  597  lttng start

run ./demo-trace

  598  lttng stop
  600  lttng view |wc -l

Previously, we were seeing only 8 events (number of events written in a
single stream), but now we see 16 events (each event is dispatched into
two streams).

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

Add channel ID field to attr

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

Remove useless else clause

Reported-by: Keun-O Park <keun-o.park@windriver.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

tracepoint: move "probe" test outside of loop

This is a slow-path optimisation.

Reported-by: Sahara <keun-o.park@windriver.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix uninitialized has_loglevel variable

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

Fix clang warnings

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

Cleanup: work-around clang unused result warning

Not useful for CHAN_WARN_ON() macro.

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

Cleanup compile warning

ustctl.c: In function 'ustctl_init':
ustctl.c:1772:2: warning: implicit declaration of function
'lttng_ring_buffer_client_overwrite_rt_init'
[-Wimplicit-function-declaration]
ustctl.c:1774:2: warning: implicit declaration of function
'lttng_ring_buffer_client_discard_rt_init'
[-Wimplicit-function-declaration]
ustctl.c: In function 'ustctl_exit':
ustctl.c:1781:2: warning: implicit declaration of function
'lttng_ring_buffer_client_discard_rt_exit'
[-Wimplicit-function-declaration]
ustctl.c:1783:2: warning: implicit declaration of function
'lttng_ring_buffer_client_overwrite_rt_exit'
[-Wimplicit-function-declaration]

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

Cleanup: remove unused variables

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

tracepoint: Don't add NULL probes

Reported-by: Sahara <keun-o.park@windriver.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Remove mention of locking issues associated with dlopen usage

This notice has been removed from the README as part of revision
b834dead.

Add a warning relating to dlclose() usage detailed in issue 447 in both
the man page and the README file.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Implement read timer (for RT)

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

Only flush when there are readers active

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

Add mutex for channel wakeup fd update

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

Fix: fields should be initialized to NULL

Fixes uninitialized pointer free.

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

Implement ustctl_duplicate_ust_object_data

Allow sessiond to duplicate its object data. Useful for per-uid buffers.

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

Add channel wakeup fd to monitor close

Add channel wakeup fd, so consumer can keep its handle on the stream
wakeup_fd (for periodic timer flush), and yet still discover that an
application has closed a channel or exited.

Requires to be updated in locked-step with lttng-tools
"Add channel wakeup fd to monitor close"

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

Fix: refcount issue in lttng-ust-abi.c

The following scenario could lead to a segmentation fault in
applications when the sessiond disappears or when the application try to
exit. This is caused by incorrect handling of reference counts.

This can happen in very particular race scenario, described as follows:

1) The sessiond asks for "release" of one or more objects (e.g. a
   session object), but _without_ asking for release of _all_ objects
   referencing the session.
2) The application exits, thus calling objd_table_destroy(). It walks on
   all objects, decrementing their reference count, freeing memory when
   their reference count reaches "1".

However, here is the issue: since "release" has already been performed
by sessiond on the session object, this extra reference count unref
performed by objd_table_destroy() can make the session object disappear
while it is still needed by either the channel object or the enabler
object. Therefore, we can experience a segmentation fault when we try to
unref and free the channel or enabler objects within
objd_table_destroy().

Fix this issue by adding the concept of an "owner reference". Only
objd_table_destroy(), lttng_ust_objd_table_owner_cleanup(), "release"
commands, and failure paths of object creation are allowed to decrement
the owner reference. We restrict objd_table_destroy() and
lttng_ust_objd_table_owner_cleanup() to _only_ decrement refcount of
objects _if_ their owner reference is still held.

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