Michael Jeanson [Wed, 2 Jun 2021 14:55:22 +0000 (10:55 -0400)]
Add serialized ABI definition files
This commit contains the serialized ABI definitions for a typical build
of the liburcu librairies. This information is extracted using
libabigail (https://sourceware.org/libabigail/).
The artefacts used to generate these were built with CFLAGS="-O0 -ggdb".
You can compare the serialized ABI with a shared object to check for
breaking changes. For example, here we compare an in-tree built version
of liburcu-memb.so with the serialized ABI of stable-0.13 :
Michael Jeanson [Tue, 1 Jun 2021 21:01:49 +0000 (17:01 -0400)]
bump SONAME major to 8
In URCU 0.11, we introduced new symbols to clean up the library symbol
namespacing, using the "alias" attribute to keep emitting the old
symbols, expecting to preserve ABI backward compatibility.
Unfortunately, it turns out that even though it works well for function
symbols, it is broken for public global variables due to the way ELF
copy relocation works.
When building a non-PIC executable that uses an extern variable, a .bss
symbol is emitted in the executable. This will take precedence over the
symbol implemented within the library in the Global Symbol Table.
Unfortunately, the alias within the library will not be aware that the
actual GST symbol differs from its alias within the library, and the
addresses for the symbol and its alias will differ at runtime.
Considering that this compatibility issue affects official library
releases, there is little we can do beyond documenting this issue, and
bumping the Userspace RCU major soname for the next (0.13) release.
Change-Id: I0ca8407dcffd871f025814923c6e329ec260133a Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Michael Jeanson [Fri, 7 May 2021 15:34:33 +0000 (11:34 -0400)]
fix: clock_gettime on macOs
Newer version of macOs have an implementation of clock_gettime() that
requires additionnal setup, move the platform specific code first so it
is always used.
Change-Id: I12fcdeff6c0ae59bc1a13f4e2cd7f4ebcedfc253 Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fix: rculist header: use parenthesis around macro parameters
The coding style followed across liburcu is to use parenthesis around
macro parameters when it would otherwise lead to unexpected results due
to priority of operators. Fix rculist.h to follow this coding style.
Fix: rcuhlist header: use parenthesis around macro parameters
The coding style followed across liburcu is to use parenthesis around
macro parameters when it would otherwise lead to unexpected results due
to priority of operators. Fix rcuhlist.h to follow this coding style.
Fix: hlist header: use parenthesis around macro parameters
The coding style followed across liburcu is to use parenthesis around
macro parameters when it would otherwise lead to unexpected results due
to priority of operators. Fix hlist.h to follow this coding style.
Fix: list.h: use parenthesis around macro parameters, caa_container_of()
The coding style followed across liburcu is to use parenthesis around
macro parameters when it would otherwise lead to unexpected results due
to priority of operators. Fix list.h to follow this coding style.
Use caa_container_of() for cds_list_entry rather than open-code the
pointer arithmetic.
Comparing an offset from an object with NULL is undefined behavior
and the compiler may assume that this is never true.
This is indeed what is observed with gcc-10 miscompiling
cds_hlist_for_each_entry_rcu_2().
Fix this by introducing cds_hlist_entry_safe() rather than open-coding
the NULL check comparisons, and move cds_hlist_for_each_entry_2()
and cds_hlist_for_each_entry_safe_2() to this scheme as well.
Fix: use __atomic_load() rather than atomic load explicit
Use __atomic_load (gcc extension) rather than atomic load explict
(C11/C++11) for rcu_dereference because it does not require the input
type to be _Atomic. This fixes a regression with clang introduced by
commit 380f4b19052 ("Fix: use atomic load memory_order_consume for
rcu_dereference on C11/C++11").
Note that the cmm_smp_read_barrier_depends is removed when using
__ATOMIC_CONSUME because their memory ordering effect is redundant.
Michael Jeanson [Tue, 13 Apr 2021 20:19:06 +0000 (16:19 -0400)]
fix: HAVE_SCHED_SETAFFINITY is not defined
Use '#ifdef' instead of '#if' to test if HAVE_SCHED_SETAFFINITY is
defined. Both work but using '#if' on an undefined macro will generate a
warning with '-Wundef'.
Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ieb46ddab9ba033a5c552dbe78ac398cea0a641e8
Michael Jeanson [Thu, 1 Apr 2021 18:39:01 +0000 (14:39 -0400)]
cleanup: explicitly mark unused parameters (-Wunused-parameter)
Add the 'unused' attribute to function parameters that are unused to
allow turning on -Wunused-parameter and distinguish unused parameters
that are actual errors.
Change-Id: Ie585e37f9d38718543a31aee2e7ab3428cdfd0a5 Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Michael Jeanson [Thu, 18 Mar 2021 23:53:28 +0000 (19:53 -0400)]
Introduce AE_FEATURE to manage configure features
The new AE_FEATURE set of macros are wrappers over autoconf's
AC_ARG_ENABLE. The main objective is to make the m4sh code more readable
to the less seasoned autotools enthusiast among us and reduce the
duplication of code with its associated bugs.
The AE prefix was chosen to mean "Autotools EfficiOS" and is part of an
effort to standardize our custom macros across all our autotools based
projects.
Change-Id: Ief565473b38150fe2104492c6339bac73efba895 Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Michael Jeanson [Thu, 18 Mar 2021 21:50:48 +0000 (17:50 -0400)]
tests: Move tap-driver.sh out of the autotools aux directory
We have made local modifications to this script, move it to the test
suite directory so it doesn't get overwritten by an updated version from
autotools.
This is part of an effort to standardise our autotools setup across
project to simplify maintenance.
Change-Id: I4bc0bdbff05d03d8e4c0f9dcda51cf6a6cf7fec4 Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Michael Jeanson [Mon, 25 Jan 2021 18:36:24 +0000 (13:36 -0500)]
fix: exclude clang from GCC version blacklists
URCU_GCC_VERSION is used to blacklist specific GCC versions with known
bugs, clang also defines these macros to an equivalent GCC version it
claims to support, so exclude it.
Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Idf0980fddca6533313a3367601ddda8d8e13bfdf
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.
Michael Jeanson [Fri, 11 Dec 2020 18:52:10 +0000 (13:52 -0500)]
Don't force a target and optimization level on ARMv7
We shouldn't force a specific target cpu for the compiler on ARMv7 but
let the system or the user choose it. If some of our code depends on a
specific target CPU features, it should be compile tested.
Also remove the default optimisation level of O1, it's potentially a
workaround to an early armv7 compiler performance problem and anyway
most builds will have an optimisation level flag set in the CFLAGS which
will override this one.
Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Acked-by: Paul E. McKenney <paulmck@kernel.org> Cc: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I1d1bb5cc0fa0be8f8b1d6a9ad7bf063809be1aef
Michael Jeanson [Thu, 10 Dec 2020 21:52:30 +0000 (16:52 -0500)]
Use DMB only on ARMv7
Remove the configure time CONFIG_RCU_ARM_HAVE_DMB option and replace it
by compile time detection based on the ARM ISA version. This makes sure
we unconditionnaly use the DMB instruction only on ARMv7 where it's part
of the baseline ISA.
This will change the behavior on ARMv6 platform that possibly have this
instruction but it was probably already broken since we use the 'ISH'
option which doesn't seem to be valid on this ISA.
This will also allow sharing headers in a multi-arch environment and
reduce the build system complexity.
Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Cc: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I8e56ada55148d8e0f198c3d2e741ea414de5fef2
Michael Jeanson [Wed, 9 Dec 2020 17:05:31 +0000 (12:05 -0500)]
fix: bump tests thread limit to 4096
Machines with more than 128 CPUs are becomming more common. A
future-proof fix here would be to dynamically allocate the array, but in
the meantime bump the limit to 4096 to fix the problem on a 160 CPUs
ppc64el system where this was reported.
Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Cc: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ib3cb5d8cb4515e6f626be33c2685fa38cb081782
Michael Jeanson [Tue, 17 Nov 2020 23:28:20 +0000 (18:28 -0500)]
Compile time futex syscall detection
The futex syscall availability is detected at configure time using a
simple compile test. Replace this with compile time detection using the
same test. This would allow sharing headers in a multi-arch environment
and reduce the build system complexity.
Change-Id: Ief709429e8908d0fd2d268d42f4a89d9fc14b91b Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Michael Jeanson [Tue, 17 Nov 2020 23:08:49 +0000 (18:08 -0500)]
Static arch and uatomic headers
Replace the somewhat hackish symlinking of architecture specific headers
at configure time with compile time detection using compiler defines.
This would allow sharing headers in a multi-arch environment and reduce
the build system complexity.
Change-Id: I4900a18dab70bb0e51d1a8500581a445acd44cdf Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Michael Jeanson [Fri, 30 Oct 2020 19:39:56 +0000 (15:39 -0400)]
fix: add -lurcu-common to pkg-config libs for each flavor
The urcu-common library contains common code like the write-free queue
and compat code, each urcu flavor library is dynamicly linked with it.
Most but not all toolchains will automatically link an executable with a
transitive depency of an explicitly linked library if said binary uses a
symbol from the transitive dependency.
Since this behavior is not present in all toolchains, add
'-lurcu-common' to the 'Libs' field of each flavors pkg-config file so
that executables using symbols from urcu-common can be reliably linked
using pkg-config.
Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Paul E. McKenney [Thu, 22 Oct 2020 22:30:21 +0000 (15:30 -0700)]
call_rcu: Fix race between rcu_barrier() and call_rcu_data_free()
The current code can lose RCU callbacks at shutdown time, which can
result in hangs. This lossage can happen as follows:
o A thread invokes call_rcu_data_free(), which executes up through
the wake_call_rcu_thread(). At this point, the call_rcu_data
structure has been drained of callbacks, but is still on the
call_rcu_data_list. Note that this thread does not hold the
call_rcu_mutex.
o Another thread invokes rcu_barrier(), which traverses the
call_rcu_data_list under the protection of call_rcu_mutex,
a list which still includes the above newly drained structure.
This thread therefore adds a callback to the newly drained
call_rcu_data structure. It then releases call_rcu_mutex and
enters a mystifying loop that does futex stuff.
o The first thread finishes executing call_rcu_data_free(),
which acquires call_rcu_mutex just long enough to remove the
newly drained call_rcu_data structure from call_rcu_data_list.
Which causes one of the rcu_barrier() invocation's callbacks to
be leaked.
o The second thread's rcu_barrier() invocation never returns
resulting in a hang.
This commit therefore changes call_rcu_data_free() to acquire
call_rcu_mutex before checking the call_rcu_data structure for callbacks.
In the case where there are no callbacks, call_rcu_mutex is held across
both the check and the removal from call_rcu_data_list, thus preventing
rcu_barrier() from adding a callback in the meantime. In the case where
there are callbacks, call_rcu_mutex must be momentarily dropped across
the call to get_default_call_rcu_data(), which can itself acquire
call_rcu_mutex. This momentary drop is not a problem because any
callbacks that rcu_barrier() might queue during that period of time will
be moved to the default call_rcu_data structure, and the lock will be
held across the full time including moving those callbacks and removing
the call_rcu_data structure that was passed into call_rcu_data_free()
from call_rcu_data_list.
With this fix, a several-hundred-CPU test successfully completes more
than 5,000 executions. Without this fix, it fails within a few tens
of executions. Although the failures happen more quickly on larger
systems, in theory this could happen on a single-CPU system, courtesy
of preemption.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Stephen Hemminger <stephen@networkplumber.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: <lttng-dev@lists.lttng.org> Cc: <linux-kernel@vger.kernel.org> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fix: tls-compat.h exposes compiler-dependent public configuration
Exposing the storage class chosen by ax_tls.m4 in a public header is
a bad idea, because if a recent gcc is used when configuring
liburcu, thus detecting C11, it will choose _Thread_local. Then, if an
external project uses urcu/tls-compat.h with an older gcc (e.g. 4.8),
it will fail to build, because that storage class is unknown, and
__thread should be used instead.
Therefore, use a preprocessor conditional on __cplusplus to detect C++11
(and use thread_local). Else, the STDC version is used to select
_Thread_local. Else check if _MSC_VER is defined to select
__declspec(thread), or else rely on __thread as fallback.
On architectures where "char" is signed, it should be cast to unsigned
char before being passed as parameter to isdigit or isspace. Based on
their man page:
These functions check whether c, which must have the value of an
unsigned char or EOF, falls into a certain character class according to
the specified locale.
Passing a signed char as parameter is invalid if the values fall into
the negative range of the signed char.
urcu-bp: perform thread registration on urcu_bp_register_thread
Some real-time use-cases (e.g. Xenomai) require to perform urcu-bp
thread registration early in the thread life-time before it starts
performing real-time tasks.
Currently, this can be achieved by issuing a urcu_bp_read_lock() and
urcu_bp_read_unlock() pair, or by using urcu_bp_read_ongoing(), while in
the initialization phrase.
However, it seems natural to expect that calling urcu_bp_register_thread()
would have the side effect to perform the lazy thread registration
immediately rather than being a no-op.
cds_lfht_is_node_deleted parameter can be marked const
Mark the cds_lfht_node pointer parameter of cds_lfht_is_node_deleted
as const. The fact that this parameter is mutable makes it harder to
use liburcu in const-correct code.
In urcu-signal flavor, call_rcu_thread calls synchronize_rcu which
will send SIGRCU signal to all registed threads, and then loops to
wait need_mb to be cleared. However, the registed workqueue_thread
does not process the SIGRCU signal, and never clear the need_mb.
Based on above, call_rcu_thread and workqueue_thread will wait
forever for completion of the grace period: call_rcu_thread which holds
the rcu_registry_lock, waits for workqueue_thread to do cmm_smp_mb.
While workqueue thread never does cmm_smp_mb because of signal blocking,
and it will eventually wait to get rcu_registry_lock in do_resize_cb.
The phenomenon is as follows, which is easy to be triggered:
(gdb) t 2
[Switching to thread 2 (Thread 0xffff83c3b080 (LWP 27116))]
0 0x0000ffff845296c4 in poll () from /lib64/libc.so.6
(gdb) bt
0 0x0000ffff845296c4 in poll () from /lib64/libc.so.6
1 0x0000ffff8461b93c in force_mb_all_readers () at urcu.c:241
2 0x0000ffff8461c748 in smp_mb_master () at urcu.c:249
3 urcu_signal_synchronize_rcu () at urcu.c:445
4 0x0000ffff8461d004 in call_rcu_thread at urcu-call-rcu-impl.h:364
5 0x0000ffff845eb8bc in start_thread () from /lib64/libpthread.so.0
6 0x0000ffff845335cc in thread_start () from /lib64/libc.so.6
(gdb) t 3
[Switching to thread 3 (Thread 0xffff8443c080 (LWP 27191))]
0 0x0000ffff845f51c4 in __lll_lock_wait () from /lib64/libpthread.so.0
(gdb) bt
0 0x0000ffff845f51c4 in __lll_lock_wait () from /lib64/libpthread.so.0
1 0x0000ffff845ee048 in pthread_mutex_lock () from /lib64/libpthread.so.0
2 0x0000ffff8461b814 in mutex_lock ( <rcu_registry_lock>) at urcu.c:157
3 0x0000ffff8461b9e4 in urcu_signal_unregister_thread () at urcu.c:564
4 0x0000ffff8463e62c in do_resize_cb (work=0x11e2e790) at rculfhash.c:2042
5 0x0000ffff8463c940 in workqueue_thread (arg=0x11e1d260) at workqueue.c:228
6 0x0000ffff845eb8bc in start_thread () from /lib64/libpthread.so.0
7 0x0000ffff845335cc in thread_start () from /lib64/libc.so.6
So we should not block SIGRCU in workqueue thread to avoid blocking
forever in the grace period awaiting on the worker thread when using
urcu-signal flavor.
Signed-off-by: hewenliang <hewenliang4@huawei.com> Co-developed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Found by Coverity:
CID 1357055 (#1 of 1): Unchecked return value (CHECKED_RETURN)
4. check_return: Calling pthread_mutex_lock without checking return value
(as is done elsewhere 44 out of 48 times).
Michael Jeanson [Mon, 3 Jun 2019 20:36:43 +0000 (16:36 -0400)]
Fix: SONAME bump to 6.1.0
In commit d6c78161aed9b2d550ce201b0a8cd5b3ee515ac8 we bumped the 'age'
part of the library version with the intention of keeping the same major
SONAME because we only introduced new symbols. However by bumping the
'age' and not the 'current' we substracted 1 to the major SONAME which
we did not intend. Seems like we missed this in testing.
Fix it by bumping the 'current' to end up with an SONAME of 6.1.0 which
is what we originally intended.
From the libtool manual for reference :
Programs using the previous version may use the new version as drop-in
replacement, but programs using the new version may use APIs not present
in the previous one. In other words, a program linking against the new
version may fail with “unresolved symbols” if linking against the old
version at runtime: set revision to 0, bump current and age.
Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cleanup: update code layout to fix old gcc warning
Some CI jobs show:
urcu-pointer.o
13:46:22 In file included from urcu.c:49:0:
13:46:22 urcu-wait.h:70:9: warning: missing initializer for field 'lock' of 'struct cds_wfs_stack' [-Wmissing-field-initializers]
13:46:22 struct urcu_wait_queue name = URCU_WAIT_QUEUE_HEAD_INIT(name)
13:46:22 ^
13:46:22 urcu.c:150:8: note: in expansion of macro 'DEFINE_URCU_WAIT_QUEUE'
13:46:22 static DEFINE_URCU_WAIT_QUEUE(gp_waiters);
13:46:22 ^
13:46:22 In file included from urcu-wait.h:27:0,
13:46:22 from urcu.c:49:
13:46:22 ../include/urcu/wfstack.h:92:18: note: 'lock' declared here
13:46:22 pthread_mutex_t lock;
13:46:22
Building liburcu with --enable-cds-lfht-iter-debug and rebuilding
application to match the ABI change allows finding cases where the
hash table iterator is re-purposed to be used on a different hash
table while still being used to iterate on a hash table.
This is a common programming mistake that happens often enough
to justify creating a debugging mode to track this automatically.
Michael Jeanson [Wed, 12 Dec 2018 20:01:37 +0000 (15:01 -0500)]
Port: no symbols aliases on MacOS
There is no equivalent to symbols aliases on MacOS, this will
unfortunatly break the ABI for SONAME(6) and will require a rebuild of
client applications.
Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Michael Jeanson [Fri, 30 Nov 2018 19:28:51 +0000 (14:28 -0500)]
Add -Wextra to CFLAGS
Edited by Mathieu Desnoyers:
Use /* fall through */ rather than __attribute__((fallthrough)) to
stay compatible with clang and gcc < 7. The fallthrough attribute
was introduced in gcc 7.
Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Use new header locations for includes from urcu code
This also moves urcu/static/urcu-pointer.h to urcu/static/pointer.h.
Considering that it is not meant to be included directly by library
users, it should not cause any problem.
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