Hide private snprintf symbols

The major SONAME bump to '1' gives us the opportunity to hide private
symbols that should never have been visible.

Change-Id: Iee731f585712c997fc92bc252ad4e4a7a4bddf3c
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Hide private ust-comm.h symbols

The major SONAME bump to '1' gives us the opportunity to hide private
symbols that should never have been visible.

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I57a6d90535e01d85abb26c42da117828d1334c72

Hide private ust-snprintf.h symbols

The major SONAME bump to '1' gives us the opportunity to hide private
symbols that should never have been visible.

Change-Id: I893e18b4fe4e9c1dc45e30fed8a10f28a367cc7c
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Hide private share.h symbols

The major SONAME bump to '1' gives us the opportunity to hide private
symbols that should never have been visible.

While we're at it, namespace the symbols that were previously part of
the ABI.

Change-Id: I75c4a65969982f2097365441f92de0d3082c8172
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Hide private ust-dynamic-type.h symbols

The major SONAME bump to '1' gives us the opportunity to hide private
symbols that should never have been visible.

Change-Id: I8a366479704830fe098d425f97a556ed5069d3bc
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Document why context provider is ABI without a public header

The context provider feature is part of the ABI and used by the Java jni
interface. However, some test code and documentation needs to be written
before it is exposed to users with a public header.

Change-Id: I24fcd5cf4a79e3f3c95654dd915dbe7c5380b66c
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Use 'ust-' prefix for all global private headers

Reduce the chances of a header filename clash by namespacing all the
global public header files with 'ust-'. Also, consistency makes me
happy.

Change-Id: I41a0b32885a5568ebf4c554893bde8a1ea5c3402
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Move private headers out of 'lttng/' public header dir

The 'include/lttng' directory contains a mix of public and private
headers. Move the private header files out of this directory to reduce
confusion.

Change-Id: I48c3c4c0e724b4a7665777b95bd9a18efdb6a03a
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix: lttng_event_notifier_group_error_counter_cmd does not respect caller convention

The callers of lttng_event_notifier_group_error_counter_cmd (via
callback) expects that, on success, the object for which the ownership was
taken be set to -1 or NULL.

In this case, the shm_fd filed was not set to -1. Resulting in the
caller closing the fd and leading to errors on subsequent call.

e.g:
 sample: lttng-ust-fd-tracker.c:300: int lttng_ust_add_fd_to_tracker(int): Assertion `!IS_FD_SET(fd, lttng_fd_set)' failed.
 Error: Error sending counter cpu data to UST tracer: status=APP_DEAD
 Error: Failed to setup event notifier error accounting for app
 ./test.sh: line 5: 2650455 Aborted                 (core dumped) ../lttng-ust/doc/examples/easy-ust/sample
 lttng-sessiond: ustctl.c:192: int ustctl_release_object(int, struct lttng_ust_object_data *): Assertion `0' failed.

Change-Id: I79b242768cf7d27cd9a50c31b56423c8de08abd5
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Move to kernel style SPDX license identifiers

The SPDX identifier is a legally binding shorthand, which can be used
instead of the full boiler plate text.

See https://spdx.org/ids-how for details.

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ib61c375f72e6712e16654cfc9d97dae199e8b753

fix: unix socket peercred on FreeBSD

Include 'sys/un.h' for LOCAL_PEERCRED.

The uid member of 'struct xucred' is 'cr_uid'.

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I6d94e5ad53292401afebeae0cbbba82e7568a847

Fix: uninitialized variable in lib_ring_buffer_channel_switch_timer_start

Found by Coverity:
** CID 1447027:  Uninitialized variables  (UNINIT)
/libringbuffer/ring_buffer_frontend.c: 810 in lib_ring_buffer_channel_switch_timer_start()

>>>     CID 1447027:  Uninitialized variables  (UNINIT)
>>>     Using uninitialized value "sev". Field "sev._sigev_un" is uninitialized when calling "timer_create".

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Iaa66e5612ff1c51b50c4c0b8f30f3695e1b03153

Fix: "Cleanup: clarify bytecode ownership"

The function lttng_event_notifier_enabler_attach_capture_bytecode
have also been adapted to this change.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I6d8a984af829356329f933b552f9ada34387fd2c

Fix: Use unix socket peercred for pid, uid, gid credentials

Currently, the session daemon trust the pid, ppid, uid, and gid values
passed by the application, but should really validate the uid using unix
socket peercred. This fix uses the peercred values rather than the
values provided by the application on registration for:

- pid, uid and gid on Linux,
- uid and gid on FreeBSD.

This should improve how the session daemon deals with containerized
applications on Linux as well. Applications are required to be either in
the same pid namespace, or in a pid namespace nested within the pid
namespace of the lttng-sessiond, so the session daemon can map the
application pid to something meaningful within its own pid namespace.
Applications in a unrelated (disjoint) pid namespace will be refused by
the session daemon.

About the uid and gid with user namespaces on Linux, those will provide
meaningful IDs if the application user namespace is either the same as
the user namespace of the session daemon, or a nested user namespace.
Otherwise, the IDs will be that of /proc/sys/kernel/overflowuid and
/proc/sys/kernel/overflowgid, which typically maps to nobody.nogroup on
current distributions.

Given that fetching the parent pid (ppid) of the application would
require to use /proc/<pid>/status (which is racy wrt pid reuse), expose
the ppid provided by the application on registration instead, but only
in situations where the application sits in the same pid namespace as
the session daemon (on Linux), which is detected by checking if the pid
provided by the application matches the pid obtained using unix socket
credentials. The ppid is only used for logging/debugging purposes in the
session daemon anyway, so it is OK to use the value provided by the
application for that purpose.

Fixes: #1286
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I94742e57dad642106908d09e2c7e395993c2c48f

Move and hide new 'lttng_ust_counter_create' private symbol

Change-Id: I8306d4990243c2d5d098e164202c4f0a6fac7abf
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Move and hide new time_ns private symbols

Change-Id: I47bb61832d59385d2c296b07058dd37f3af335e0
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Move and hide new 'lttng_counter_transport_*' private symbols

Change-Id: If7da4f9a2a046d2bce183d1c0d9016c89a8ce882
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Hide new 'lttng_counter_client_percpu_*' private symbols

Change-Id: I6b0541fe745b2bc4df0be78ee1a2d5d3f708ada8
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Hide new 'ustcomm_recv_*' private symbols

Change-Id: I9be32b4d46af9ef2c94df403d8e95ce8dafeee44
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Hide new 'lttng_ust_lfht_*' private symbols

Change-Id: Ief99b5ecda492eb84f4196cb1630810be9944cfc
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Hide new 'lttng_release_event_notifier_group_error_counter' private symbol

Change-Id: Ie90fce9d29d5d12c970ae8b6d473e38498281f76
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Hide new 'lttng_fixup_time_ns_tls' private symbol

Change-Id: Id058993bfa973e4f0c272388ef309b7a1167ade9
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Hide new 'lttng_counter_*' private symbols

Change-Id: Ie2a1086e829fc2aacf8ba74a33ba0b87bbbb60fc
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Hide new 'lttng_ust_compat_futex_*' private symbols

Change-Id: Ia71c7e07e0b44a69d8252200d2233ed73a6a3bfe
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Hide new 'lttng_ust_context_set_event_notifier_group_provider' private symbol

Change-Id: I1547e0c1b7ce83c1f01316b9e0a2daffaa274bb3
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Hide new 'lttng_bytecode_*' private symbols

Change-Id: I467f6e8651e91e537301090f882f39d2eede1b84
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Hide new 'lttng_context_init_all' private symbol

Change-Id: Id709930e70f2b612ac93a97ee1091d6f64675d28
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Hide new 'lttng_counter_*' private symbols

Change-Id: Ief9322ba0d0d2967f87deb058628e4eeac0d492a
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Hide mew 'lttng_msgpack_*' private symbols

Change-Id: Ib5a5aa2f3c84e723972742cb91f78495be086539
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Hide new 'patient_writev' private symbol

Change-Id: I708373d94cce6ae99dda82857b927d816edb86a7
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Remove unused deprecated and backward compatibility fields

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ia062e1ba58770905e053d6fc01a9800b3f162e70

Remove backward compatibility for liburcu-bp

Now that the soname is bumped, there is no backward compatibility to
keep for tracepoint call sites using liburcu-bp for synchronization,
so this compatibility code can be removed.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I35d84fa1ffdb033c094b1a6989cc1c3bc29ce7f8

Cleanup: Remove deprecated symbols following soname major version bump

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I7a468395c11c1c5dfb83ef4bd16e9c38413415c5

Bump soname major to 1

The event notifier (trigger) feature required a significant rework of
public data structures which should never have been made public in the
first place.

Bump the soname major to 1, which will require applications and
tracepoint providers to rebuild against an updated lttng-ust to use it.

Old applications and tracepoint providers linked against libraries with
major soname 0 should be able to co-exist on the same system.

Now (before the next release) is a good time to eliminate LTTng-UST APIs
which were made public by accident.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I804c875ab7c0ae30daaab4817614574ccebc26c8

Fix: memory and fd leaks in error counter

Use a regular pattern for all commands:

If the command callback takes ownership of a pointer or file descriptor,
it sets them to NULL or -1. Therefore, the caller can always try to free
the pointer, or close it if it is greater or equal to 0.

This eliminates memory and fd leaks on error.

Change-Id: I4916920095526c166636c6a432b95fdd6fd1ca4b
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Cleanup: clarify bytecode ownership

Use a regular pattern for all commands:

If the command callback takes ownership of a pointer or file descriptor,
it sets them to NULL or -1. Therefore, the caller can always try to free
the pointer, or close it if it is greater or equal to 0.

Change-Id: Ie155d3cff80930271417075d693aa4528decbfc3
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Cleanup: clarify ownership of excluder

Use a regular pattern for all commands:

If the command callback takes ownership of a pointer or file descriptor,
it sets them to NULL or -1. Therefore, the caller can always try to free
the pointer, or close it if it is greater or equal to 0.

Change-Id: I3947721841222859f4f4eab15ae94856921eb09b
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix: event notifier group: fix fd leak on error

Use a regular pattern for all commands:

If the command callback takes ownership of a pointer or file descriptor,
it sets them to NULL or -1. Therefore, the caller can always try to free
the pointer, or close it if it is greater or equal to 0.

This eliminates memory and fd leaks on error.

Change-Id: If5181a0c438f2e1ac73e5d4d63d5cde21cc97e52
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix: stream fd leaks on error

Use a regular pattern for all commands:

If the command callback takes ownership of a pointer or file descriptor,
it sets them to NULL or -1. Therefore, the caller can always try to free
the pointer, or close it if it is greater or equal to 0.

This eliminates memory and fd leaks on error.

Change-Id: I447129ab1672ce4fc6cf3c0baf18dbf27bfcfaf8
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix: channel leak on error

Use a regular pattern for all commands:

If the command callback takes ownership of a pointer or file descriptor,
it sets them to NULL or -1. Therefore, the caller can always try to free
the pointer, or close it if it is greater or equal to 0.

This eliminates memory and fd leaks on error.

Change-Id: I0f9cba5fc0f4c095c8ec8f3e8970de8a10386876
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix: lttng_abi_map_channel should be static

Change-Id: If0434525f083dc20b50a7628926dadb483d30c88
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Fix: Use default visibility for tracepoint provider symbol

When building a probe provider `someprobe` with -fvisibility=hidden into
a shared library, the `__tracepoint_provider_someprobe` symbol is hidden,
which does not allow tracepoint instrumentation to link to it.

Fix this by using the "default" visibility attribute.

For a shared library built with -fvisibility=hidden, this changes the
output of nm for that symbol from:

000000000000417c b __tracepoint_provider_someprobe

(local BSS symbol)

to

000000000000417c B __tracepoint_provider_someprobe

(global (external) BSS symbol)

Fixes: #1296
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I308374f6cac58cca86e8eb19c872286a3da21a75

Fix: configure: support Autoconf 2.70

The newly-released autoconf 2.70 introduces a number of breaking
changes [1] and is being rolled-out by some distros.

Amongst those changes, the AC_PROG_CC_STDC macro is marked as obsolete
and was merged into AC_PROG_CC, which we already use. On 2.70, this
results in a warning which we handle as an error.

A version check is added to invoke the AC_PROG_CC_STDC macro only when
running a pre-2.70 version of autoconf, fixing the issue.

Also, the AX_PTHREAD macro makes use of the $as_echo built-in shell
variable which no longer exists in 2.70. A patch was submitted to the
GNU Autoconf archive in March, but there have been no signs of life
given since then [2].

As such, our local copy is updated to the latest version and the patch
(which looks fairly straight-forward / safe) is applied. This should
minimize changes once we go back to an "official" version of the macro.

[1] https://lwn.net/Articles/839395/
[2] https://savannah.gnu.org/patch/?9906

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I2f4eac788638924aa4960b54374d09de73957925

Fix: event notifier create protocol order issue

sessiond needs to send the additional command payload before awaiting
reply from UST.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I4d046e3fd2f334d728d4310ceb2b003f6bf0abed

Fix: lttng-ust 2.13 should not try to use notifiers from 2.12 or prior probes

Probe providers built against lttng-ust 2.12 or prior do not implement
the event notifier callback, and accessing desc->u.ext.event_notifier_callback
accesses beyond the size of struct lttng_event_desc.

Therefore, skip those older probe providers from the list of providers
considered for event notifications, and print an error when this
situation is encountered.

Currently, the error reporting of lttng-ust is performed through ERR(),
which is only observable on the console of the application when run with
LTTNG_UST_DEBUG=1.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: Ia8a9bae1a471ae5d30ff0364b28e1cd3a8b4e396

Fix: UST comm protocol: event notifier command is too large

The event notifier command is larger than the current largest command,
and we don't want to break the protocol between UST and tools
needlessly.

Therefore, pass the struct lttng_ust_event_notifier _after_ struct
ustcomm_ust_msg.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: Ief172eaddd113ec9092dd57bad3d73fd4c29fd51

Fix: incorrect parameters passed to vtracelog

The vtracelog APIs should be called from the vtracelog instrumentation
rather than the "tracelog" APIs, because it passes a va_list rather than
a variable argument list (...).

This can be verified by tracing the demo program doc/examples/demo-tracelog/demo-vtracelog:

Issue (corrupted trace output):

16:17:26.686073539] (+0.000000530) thinkos lttng_ust_tracelog:TRACE_ERR: { cpu_id = 2 }, { line = 31, file = "demo-vtracelog.c", func = "print_err", _msg_length = 49, msg = "This is a \"\b\" formatted 638975520 error event d68" }

Fixed:

[16:23:33.538189343] (+0.000000600) thinkos lttng_ust_tracelog:TRACE_ERR: { cpu_id = 3 }, { line = 31, file = "demo-vtracelog.c", func = "print_err", _msg_length = 52, msg = "This is a \"mystring test\" formatted 4 error event 42" }

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I330e339a3bf68fb8d9779bbc71b08c3bc033ac4e

event-notifier: Initialize `_notifier_notification` struct to zero

Valgrind reports the following use of uninitialized bytes:

  ==2233138== Syscall param writev(vector[...]) points to uninitialised byte(s)
  ==2233138==    at 0x4EA161D: __writev (writev.c:26)
  ==2233138==    by 0x4EA161D: writev (writev.c:24)
  ==2233138==    by 0x489A9EC: patient_writev (in /usr/local/lib/liblttng-ust.so.0.0.0)
  ==2233138==    by 0x48C2D5F: lttng_event_notifier_notification_send (in /usr/local/lib/liblttng-ust.so.0.0.0)
  ==2233138==    by 0x4033F3: __event_notifier_probe__tp___tptest (in /home/frdeso/projets/lttng/tools/tests/utils/testapp/gen-ust-events/gen-ust-events)
  ==2233138==    by 0x401D6E: main (in /home/frdeso/projets/lttng/tools/tests/utils/testapp/gen-ust-events/gen-ust-events)
  ==2233138==  Address 0x1ffeffedda is on thread 1's stack
  ==2233138==  in frame #2, created by lttng_event_notifier_notification_send (???:)
  ==2233138==

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I49ac4b440df61b322ac9614b09c32d1f69beedd0

Add tests/unit/libmsgpack/test_msgpack to gitignore

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I8d838f961414ee996a4a63c9270fd26ef8ba0e02

ustctl.h: use enumeration values 0, 1 for bitness

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I915d3bad476f1b11b3c972f6bb60162f3f93d519

ust-abi: use 0, 1 for counter enumerations

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

Cleanup: ust-abi: BITNESS_{32,64}BITS -> BITNESS_{32,64}

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I5175116ec93d61fe55d1c17e2e2b99b02a0e73a9

Cleanup: use tabs in ust-abi.h

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I62dcdf8bd833a04501b1088c397ca42999cf8d61

Fix: add struct lttng_event_notifier forward declaration

Add struct lttng_event_notifier forward declaration in
lttng-tracer-core.h.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I1904be0b9170979c0e3c53ce4b8dbd966a8dd04d

Fix: event notifier: notification send should be a callback

Turn notification send into a callback so probes compiled against
lttng-ust 2.13+ but executed in an environment with lttng-ust 2.12 or
prior don't trigger linker error due to missing
lttng_event_notifier_notification_send symbol.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ib51fdc09865f8ae158129417b9e26e86221881b0

Fix: ust-urcu: allow legacy applications without _LGPL_SOURCE

Allow legacy instrumented applications without _LGPL_SOURCE to
use the legacy v1 tracepoint registration API without requiring
the liburcu-bp symbols to be present in the symbol table.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Iaa574647442254b34682ea36b858a30e2ecdf98e

Fix: ust-tracepoint: make sure to expand tracepoint provider token

Using a #defined TRACEPOINT_PROVIDER with the
TRACEPOINT_EVENT_{CLASS,INSTANCE}() macros led to compilation errors,
e.g.:

gcc -I/home/chris/lttng-mwe/app/../lib -c myapp.c
gcc -o myapp myapp.o -L/home/chris/lttng-mwe/app/../lib -Wl,-rpath=/home/chris/lttng-mwe/app/../lib -lmytps -ldl
/usr/bin/ld: /home/chris/lttng-mwe/app/../lib/libmytps.so: undefined reference to `__tracepoint_provider_mismatch_TRACEPOINT_PROVIDER'
collect2: error: ld returned 1 exit status
make: *** [Makefile:9: myapp] Error 1

Use intermediate TRACEPOINT_EVENT_{CLASS,INSTANCE}() macros to make sure
that the tracepoint provider name token gets expanded.

[ Mathieu: Adapt event notifier probes as well. ]

Fixes: #1273
Signed-off-by: Christophe Bedard <bedard.christophe@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I68550a510c809f1d5f86a7e1d966dcecc3780dda

Fix: notifier: use store-release/load-acquire for error counter

The "record_error" operation is executed concurrently with setting the
error counter in the notifier group without locking, so we need to
explicitly provide existance guarantees.

The only visible transition is from NULL -> !NULL, because the only
situation reverting the error counter back to NULL is on destruction of
the notification group, after an RCU synchronisation guarantees that no
record_error can observe this pointer anymore.

Use the stronger "cmm_smp_mb()" to provide store-release/load-acquire
semantics because the explicit store-release and load-acquire are not
implemented in the CMM model yet.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I3bbeecc00ff33c5d8ad1e3fd41c8a0dc866f1943

Fix: event-notifier: Groups may not have an error counter

Issue
=====
If no error counter is attached to an event notifier group, calling
the `record_error()` function leads to a NULL pointer dereference.

Solution
========
Check if the error_counter field is allocated before dereferencing it.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I124519d37efe8eb20296cfd74027642c8e8162a5

ustctl: Initialize counter_conf struct to zero

Issue
=====
This struct is not initialize explicitly and is copied and sent through
a Unix socket to the application. This means we are currently sending
uninitialized data.

Valgrind reports the following:
  ==939806== Syscall param sendmsg(msg.msg_iov[0]) points to uninitialised byte(s)
  ==939806==    at 0x519412D: __libc_sendmsg (sendmsg.c:28)
  ==939806==    by 0x519412D: sendmsg (sendmsg.c:25)
  ==939806==    by 0x514D2BF: ustcomm_send_unix_sock (in /usr/local/lib/liblttng-ust-ctl.so.4.0.0)
  ==939806==    by 0x514C0BC: ustctl_send_counter_data_to_ust (in /usr/local/lib/liblttng-ust-ctl.so.4.0.0)
  ==939806==    by 0x4A0B14: send_counter_data_to_ust (event-notifier-error-accounting.c:237)
  ==939806==    by 0x4A046D: event_notifier_error_accounting_register_app (event-notifier-error-accounting.c:311)
  ==939806==    by 0x4B0831: ust_app_setup_event_notifier_group (ust-app.c:3956)
  ==939806==    by 0x495603: thread_dispatch_ust_registration (dispatch.c:394)
  ==939806==    by 0x487552: launch_thread (thread.c:66)
  ==939806==    by 0x5188608: start_thread (pthread_create.c:477)
  ==939806==    by 0x52E2292: clone (clone.S:95)
  ==939806==  Address 0x750fb8e is 46 bytes inside a block of size 228 alloc'd
  ==939806==    at 0x483DD99: calloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
  ==939806==    by 0x514988C: ustctl_duplicate_ust_object_data (in /usr/local/lib/liblttng-ust-ctl.so.4.0.0)
  ==939806==    by 0x4A0426: event_notifier_error_accounting_register_app (event-notifier-error-accounting.c:307)
  ==939806==    by 0x4B0831: ust_app_setup_event_notifier_group (ust-app.c:3956)
  ==939806==    by 0x495603: thread_dispatch_ust_registration (dispatch.c:394)
  ==939806==    by 0x487552: launch_thread (thread.c:66)
  ==939806==    by 0x5188608: start_thread (pthread_create.c:477)
  ==939806==    by 0x52E2292: clone (clone.S:95)

Fix
===
Initialize it to zero.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I8ce4753858a3ab3e12b94f26b94a200cef15cb06

cleanup: use <sys/syscall.h>

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I82f783fa131aa6337bc1cd7111bcd5ac85ec4d02

port: fix futex_async wrapper namespacing on FreeBSD

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I5db3fe8a596d273e6a693f3e89e26719c552f027

port: use ust-endian.h compat

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Id76539961e28a90bb7083a7a83eafd6d966cfb39

Fix: event-notifier: not propagating error counter indexes

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ie2936cd59e81410891c0fa87602d1b24132d1e35

fix: undefined symbols for tracepoints in lgpl source

Move the new internal 'urcu-ust' urcu flavor symbols to a separate
library named 'liblttng-ust-common.so' and link 'liblttng-ust.so' and
'liblttng-ust-tracepoint.so' on it.

Add this common library to the pkgconfig file which should handle the
transition for client code using it in its build system.

LGPL_SOURCE client code which doesn't use pkgconfig in its build system
will need to link with '-llttng-ust-common' instead of '-lurcu-bp' like
prior ust versions.

Change-Id: I807f997a2a94cb4f8d1bdf72002c1ae1b9fedf8d
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Remove runtime dependency on liburcu shared objects

Remove the runtime dependency on:

- liblurcu-bp.so
- liblurcu-cds.so
- compat futex code.

By integrating those into the lttng-ust project.

For rculfhash, only the minimum pieces needed by lttng-ust are
integrated (no auto-resize, no accounting).

lttng-ust still requires liburcu at build time for header dependencies.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Idffb205b27b1bb0f972523c3ce3bdaf25bfe1710

Fix: handle default switch case with -EINVAL in __lttng_counter_add

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ie7cb76725789a75cfd7cf2bdb3031a81983ad146

Bump LTTNG_UST_EVENT_NOTIFIER_PADDING to 32 bytes

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Iad5de41f09c373cf1069e81996b1201e3c02e572

Fix: memory leak in apply_context_reloc

Fixes commit b77aaa1b8edf2 ("Decouple `struct lttng_session` from filter code")

lttng_ust_add_app_context_to_ctx_rcu should be able to update the
session ctx field and not only the local ctx pointer.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I1bfdc7a1a2b6f9c579206e996572e36bf30d60e7

Fix: libcounter bad compare

Identified by Coverity.

>>>     CID 1437325:  Incorrect expression  (BAD_COMPARE)
>>>     Comparing pointer "counter_cpu_fds" against "NULL" using anything besides "==" or "!=" is likely to be incorrect.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I0d21112a0266d67fafde7a6b81e0062a7a43dce0

Fix: remove dead code in msgpack.c

Identified by Coverity. Comparing unsigned types < 0 is never true.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ic623a5b15c7053844c8e3a0b374ac3b9b929c050

Fix: counter: cast UINT*_MAX to 64-bit signed type before negative

(long long)-UINT32_MAX leads to value 1 which is not what we expect.
This is due to implicit type promotion from unsigned to signed 32-bit
integer.

Apply this to 8-bit and 16-bit types as well even though they are
not affected by this issue to keep things regular.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I8e05f270eae71cb15848075c4dfae80e8070fd80

Fix: libcounter: use LTTNG_UST_ALIGN

ALIGN() on FreeBSD does not expect the same number of arguments.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I8ce4cc94bc840a11dc30ae0679f6b2c41e11bc12

Fix: ust-abi: clarify which command is used on which object descriptor

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: If0c874ec7c8061422706582fdb66838659f7b890

Implement event notifier error counter

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ia8008a162a1e4c881fdc948a390847cb5258e4f7

Implement libcounter

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I7bc2707e8bdea712addc84d90329486cda1a24e1

Implement capturing payload on event notifiers

This commit allows the user to request a subset of payload fields of the
tracepoint to be captured when a event notifier is fired and sent back
the session daemon as part of the notification.

Captures are really similar to filter in the way they work. Like with
filters, the sessiond attaches to a event notifier one bytecode program
per field it wants to capture using the following function:

  int ustctl_set_capture(int sock, struct lttng_ust_capture_bytecode *bytecode,
         struct lttng_ust_object_data *obj_data);

The capture bytecode program is then validated and specialized for its
target tracepoint just like filter bytecode programs.

The major difference between filters and captures is with what they
return. Filters can only return _RECORD or _DISCARD for match and
no-match respectively. Captures also need to return captured values. For
this reason, we added an output parameter to the capture interpreter
function that value can be extracted.

Here is the signature of the capture interpreter function:
  uint64_t lttng_bytecode_capture_interpret(void *capture_data,
         const char *capture_stack_data,
         void *output)

When comes the time to send the notification, every capture bytecode
program is executed in turns and its output value is recorded to the
capture buffer to be sent back to the sessiond.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ia3023a4f5c0aec014b37b72f92d1a924c7eff6a2

bytecode: handle all integer types of dynamic contexts

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I86d24abd87bc6ed3fb2fbe659bc2bab877017c08

bytecode: initialize all contexts on event notifier group creation

Rename `lttng_session_context_init()` to `lttng_context_init_all()` so
to reuse the code.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: If80745677db993c1b38e158785886180d2e60d26

bytecode: Add `OBJECT_TYPE_{UN,}SIGNED_ENUM` type

Enumerations are currently converted to their integer counterparts as
soon as they are encountered.

In order to use them in captures, we need to differentiate the
enumerations from integers for the entirety of the interpretation.

This commit adds the `OBJECT_TYPE_SIGNED_ENUM` and
`OBJECT_TYPE_UNSIGNED_ENUM` to keep track of these objects.

Signed-off-by: Francis Deslauriers <fdeslaur@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I4b3ec8187a578ddc6c9d87f72d462441ba5e4a1e

Generalize `lttng_enabler_link_bytecode()` bytecode list

So it can be used for both filter and capture bytecode runtimes

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I61ac07545f8db2964f8ea0a7d40ec7be306efe90

Cleanup: rename `_lttng_filter_link_bytecode()` -> `link_bytecode()`

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ia4416b46b05869bb7ad4c754e8ff302762bfffb2

Add `interpreter_funcs` to `lttng_bytecode_runtime`

Background
==========
The current filter interpreter function signature looks like this:

  uint64_t lttng_bytecode_filter_interpret(void *filter_data,
                  const char *filter_stack_data);

The upcoming capture interpreter function will need an output parameter
to extract the top of stack register. It will look like this:

  uint64_t lttng_bytecode_capture_interpret(void *capture_data,
                  const char *capture_stack_data,
                  struct output_register *output);

Problems
========
We can't reuse the same function pointer field in `struct
lttng_bytecode_runtime` as the two interpreter functions will have
different signatures.

We can't change the signature of this existing filter function because
it's used in the tracepoint probes.

Solution
========
Add a union of callbacks to hold both interpreter functions. This also
doesn't change the layout of the `struct lttng_bytecode_runtime`
objects.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I9fcd6def9ce7783087b9648ddbf5ec71fb7b997a

bytecode: rename `lttng_filter_sync_state()` -> `lttng_bytecode_filter_sync_state()`

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I8d6386a087d5df1844bd157af571c08f41d54a9b

Implement enum and sequence capture serialization functions

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I9dff84b7213c68fbef1be582301d834720706726

Extract `handle_bytecode_recv()` function

A lot of this code will be reused for capture bytecode.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ib095033ae2b9dae6e8284ea4def0f7c69f688c63

Rename filter bytecode types and files

File renames:
- filter-bytecode.h -> bytecode.h
- lttng-filter-interpreter.c -> lttng-bytecode-interpreter.c
- lttng-filter-specialize.c -> lttng-bytecode-specialize.c
- lttng-filter-validator.c -> lttng-bytecode-validator.c
- lttng-filter.c -> lttng-bytecode.c
- lttng-filter.h -> lttng-bytecode.h

Function renames:
- `lttng_filter_interpret_bytecode_false()` -> `lttng_bytecode_filter_interpret_false()`
- `lttng_filter_interpret_bytecode()` -> `lttng_bytecode_filter_interpret()`
- `lttng_filter_specialize_bytecode()` -> `lttng_bytecode_specialize()`
- `lttng_filter_validate_bytecode()` -> `lttng_bytecode_validate()`

Type renames
- `filter_opcode_t` to `bytecode_opcode_t`

Enum renames:
- `enum filter_op` to `enum bytecode_op`
  - `FILTER_OP_*` to `BYTECODE_OP_*`
- `enum lttng_filter_ret` -> `enum lttng_bytecode_interpreter_ret`
  - `LTTNG_FILTER_DISCARD` -> `LTTNG_INTERPRETER_DISCARD`
  - `LTTNG_FILTER_RECORD_FLAG` -> `LTTNG_INTERPRETER_RECORD_FLAG`

Define renames:
- `FILTER_STACK_EMPTY` -> `INTERPRETER_STACK_EMPTY`
- `FILTER_STACK_LEN`-> `INTERPRETER_STACK_LEN`
- `FILTER_MAX_DATA_LEN` -> `BYTECODE_MAX_DATA_LEN`

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Iaab55116da5a3a8562b0f9e5b6033b556292f55b

bytecode: generalize `struct lttng_ust_filter_bytecode_node`

Rename `struct lttng_ust_filter_bytecode_node` to `struct
lttng_ust_bytecode_node` so it can be used by capture bytecode as well.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I0bb4ba4962601f1c83bf92494be4c47032f47db3

Cleanup: Rename filter functions/fields to mention "filter"

This will be cleaner when we introduce the capture bytecode functions
and fields.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I81a986386908212bf7a6814413204b54da6950c8

Add `patient_writev()` function

This function wraps the `writev()` function to make it EINTR-aware.

We are going to use this function to send multiple structs in a single
call when dealing with event notifier captures.

This function also supports partial writes even though this should never
happen with event notifier notification. We assert that the data sent is less
then PIPE_BUF in size so to take advantage of the POSIX guarantee for
write atomicity as explained in pipe(7).

The implementation was inspired by this stackoverflow.com post:
https://stackoverflow.com/questions/5853675/techniques-for-handling-short-reads-writes-with-scatter-gather

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ifd1def23f38ab95411fd4550858466451d0468ea

Add `libmsgpack` for serializing captures

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ice8ed791a0452ea9e659ffcaf9e081f47288e8d5

bytecode: allow interpreter to return any type

The bytecode interpreter when used by capture bytecode needs to return
types other than an integer or dynamic type.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ib93aaa8285ddd615b16dd6ebbf038f79880e25e8

bytecode: propagate `rev_bo` of element

When specializing and executing bytecode.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I9fc7381b397acdae02f87e941128ed89e12f7350

bytecode: set register type to `REG_PTR` even if not used

There was no need to set the field when using filter as the next
instruction would assume that the top of stack is a `REG_PTR`.

With the upcoming capture feature, we need to ensure this field is
consistent for extraction.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I8790618ddde23b29ef2a55698524c45b39ef4793

Add `lttng_bytecode_interpret_format_output()` for top of stack extraction

This new static function will be used to extract the register on the top of
stack after the execution of the bytecode. This is currently not used by the
filter bytecode but will be used by capture bytecode in the future.

The returned value is saved in a tagged union struct named `struct
lttng_interpreter_output` and can be used by the caller of the interpreter
function.

Typically, this struct will be allocated on the stack to avoid dynamic
allocation inside the tracepoint probes.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Id8a64d55f2bfb1af1657634a36d34dba5325777f

bytecode: add `REG_U64` interpreter register type

This will be used by the capture bytecode for unsigned integer
extraction.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I8ff7ec22eddcf3acb4a359ad398f97476dd079f2

Implement event notifier

The event notifier feature allows the user to get notify through a pipe
that an callsite was reached. It's really similar to a regular UST event
in that firing can be controlled by filters and exclusions. It diverges
because firing a event notifier does not end up writing to the tracing
buffers. In fact, event notifiers live outside of any sessions (i.e. no
session is needed).

Definitions
===========
A `Event notifier` is defined as an event description (event name, log level,
etc.) and a unique event notifier token.

A `Event notifier group` is a set of event notifiers sharing the same
pipe to the liblttng-ust-ctl user.

Sequence of operations
======================
  event_notifier_group_handle = ustctl_create_event_notifier_group(notification_fd)
  event_notifier_handle = ustctl_create_event_notifier(event_notifier_group_handle, event_notifier_id);
  ustctl_set_filter(event_notifier_handle, filter)
  ustctl_set_exclusion(event_notifier_handle, exclusion)
  ustctl_enable(event_notifier_handle)
  ...
  ustctl_disable(event_notifier_handle)
  ustctl_release_object(event_notifier_handle)
  ustctl_release_object(event_notifier_group_handle)

Highlevel changes
=================
- Add the event notifier probe generation macros,
- Add event notifier enabling/disabling machinery,
- Add event notifier filter machinery,
- Add event notifier exclusion machinery,
- Expose ABI structures
- Expose ABI enums
- Expose ABI cmds
- Expose ustctl functions

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I493d784cc6830cd6c7979f6f08b209521676f05c

Add token to `struct lttng_ust_event`

This token is provided by the user when registering an event rule to
UST. It is going to used to identify messages from event notifiers in
the upcoming event notifier feature.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I780c681a6775cf61a2f805b7c6aed6ff2e321ea9

Create `_for_each` function to unregister probe providers

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ic09169fb81c6ee420c60a63045532831efaa0806

Cleanup: extract function to borrow hashlist bucket

This is going to reused by the event notifier system.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I5132273ae79a84afdfbf0f88c8042c2b3828d782