This patch does not have any functionality change, we only provide a spin
count tunes for pthread adaptive spin mutex. The tunable
glibc.pthread.mutex_spin_count tunes can be used by system administrator to
squeeze system performance according to different hardware capabilities and
workload characteristics.
The maximum value of spin count is limited to 32767 to avoid the overflow
of mutex->__data.__spins variable with the possible type of short in
pthread_mutex_lock ().
The default value of spin count is set to 100 with the reference to the
previous number of times of spinning via trylock. This value would be
architecture-specific and can be tuned with kinds of benchmarks to fit most
cases in future.
I would extend my appreciation sincerely to H.J.Lu for his help to refine
this patch series.
* manual/tunables.texi (POSIX Thread Tunables): New node.
* nptl/Makefile (libpthread-routines): Add pthread_mutex_conf.
* nptl/nptl-init.c: Include pthread_mutex_conf.h
(__pthread_initialize_minimal_internal) [HAVE_TUNABLES]: Call
__pthread_tunables_init.
* nptl/pthreadP.h (MAX_ADAPTIVE_COUNT): Remove.
(max_adaptive_count): Define.
* nptl/pthread_mutex_conf.c: New file.
* nptl/pthread_mutex_conf.h: New file.
* sysdeps/generic/adaptive_spin_count.h: New file.
* sysdeps/nptl/dl-tunables.list: New file.
* nptl/pthread_mutex_lock.c (__pthread_mutex_lock): Use
max_adaptive_count () not MAX_ADAPTIVE_COUNT.
* nptl/pthread_mutex_timedlock.c (__pthrad_mutex_timedlock):
Likewise.
Suggested-by: Andi Kleen <andi.kleen@intel.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Signed-off-by: Kemi.wang <kemi.wang@intel.com>
The race leads either to pthread_mutex_destroy returning EBUSY
or triggering an assertion (See description in bugzilla).
This patch is fixing the race by ensuring that the elision path is
used in all cases if elision is enabled by the GLIBC_TUNABLES framework.
The __kind variable in struct __pthread_mutex_s is accessed concurrently.
Therefore we are now using the atomic macros.
The new testcase tst-mutex10 is triggering the race on s390x and intel.
Presumably also on power, but I don't have access to a power machine
with lock-elision. At least the code for power is the same as on the other
two architectures.
ChangeLog:
[BZ #23275]
* nptl/tst-mutex10.c: New File.
* nptl/Makefile (tests): Add tst-mutex10.
(tst-mutex10-ENV): New variable.
* sysdeps/unix/sysv/linux/s390/force-elision.h: (FORCE_ELISION):
Ensure that elision path is used if elision is available.
* sysdeps/unix/sysv/linux/powerpc/force-elision.h (FORCE_ELISION):
Likewise.
* sysdeps/unix/sysv/linux/x86/force-elision.h: (FORCE_ELISION):
Likewise.
* nptl/pthreadP.h (PTHREAD_MUTEX_TYPE, PTHREAD_MUTEX_TYPE_ELISION)
(PTHREAD_MUTEX_PSHARED): Use atomic_load_relaxed.
* nptl/pthread_mutex_consistent.c (pthread_mutex_consistent): Likewise.
* nptl/pthread_mutex_getprioceiling.c (pthread_mutex_getprioceiling):
Likewise.
* nptl/pthread_mutex_lock.c (__pthread_mutex_lock_full)
(__pthread_mutex_cond_lock_adjust): Likewise.
* nptl/pthread_mutex_setprioceiling.c (pthread_mutex_setprioceiling):
Likewise.
* nptl/pthread_mutex_timedlock.c (__pthread_mutex_timedlock): Likewise.
* nptl/pthread_mutex_trylock.c (__pthread_mutex_trylock): Likewise.
* nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full): Likewise.
* sysdeps/nptl/bits/thread-shared-types.h (struct __pthread_mutex_s):
Add comments.
* nptl/pthread_mutex_destroy.c (__pthread_mutex_destroy):
Use atomic_load_relaxed and atomic_store_relaxed.
* nptl/pthread_mutex_init.c (__pthread_mutex_init):
Use atomic_store_relaxed.
This patch adds the thrd_* definitions from C11 threads (ISO/IEC 9899:2011),
more specifically thrd_create, thrd_curent, rhd_detach, thrd_equal,
thrd_exit, thrd_join, thrd_sleep, thrd_yield, and required types.
Mostly of the definitions are composed based on POSIX conterparts, such as
thrd_t (using pthread_t). For thrd_* function internally direct
POSIX pthread call are used with the exceptions:
1. thrd_start uses pthread_create internal implementation, but changes
how to actually calls the start routine. This is due the difference
in signature between POSIX and C11, where former return a 'void *'
and latter 'int'.
To avoid calling convention issues due 'void *' to int cast, routines
from C11 threads are started slight different than default pthread one.
Explicit cast to expected return are used internally on pthread_create
and the result is stored back to void also with an explicit cast.
2. thrd_sleep uses nanosleep internal direct syscall to avoid clobbering
errno and to handle expected standard return codes. It is a
cancellation entrypoint to be consistent with both thrd_join and
cnd_{timed}wait.
3. thrd_yield also uses internal direct syscall to avoid errno clobbering.
Checked with a build for all major ABI (aarch64-linux-gnu, alpha-linux-gnu,
arm-linux-gnueabi, i386-linux-gnu, ia64-linux-gnu, m68k-linux-gnu,
microblaze-linux-gnu [1], mips{64}-linux-gnu, nios2-linux-gnu,
powerpc{64le}-linux-gnu, s390{x}-linux-gnu, sparc{64}-linux-gnu,
and x86_64-linux-gnu).
Also ran a full check on aarch64-linux-gnu, x86_64-linux-gnu, i686-linux-gnu,
arm-linux-gnueabhf, and powerpc64le-linux-gnu.
[BZ #14092]
* conform/Makefile (conformtest-headers-ISO11): Add threads.h.
(linknamespace-libs-ISO11): Add libpthread.a.
* conform/data/threads.h-data: New file: add C11 thrd_* types and
functions.
* include/stdc-predef.h (__STDC_NO_THREADS__): Remove definition.
* nptl/Makefile (headers): Add threads.h.
(libpthread-routines): Add new C11 thread thrd_create, thrd_current,
thrd_detach, thrd_equal, thrd_exit, thrd_join, thrd_sleep, and
thrd_yield.
* nptl/Versions (libpthread) [GLIBC_2.28]): Add new C11 thread
thrd_create, thrd_current, thrd_detach, thrd_equal, thrd_exit,
thrd_join, thrd_sleep, and thrd_yield symbols.
* nptl/descr.h (struct pthread): Add c11 field.
* nptl/pthreadP.h (ATTR_C11_THREAD): New define.
* nptl/pthread_create.c (START_THREAD_DEFN): Call C11 thread start
routine with expected function prototype.
(__pthread_create_2_1): Add C11 threads check based on attribute
value.
* sysdeps/unix/sysdep.h (INTERNAL_SYSCALL_CANCEL): New macro.
* nptl/thrd_create.c: New file.
* nptl/thrd_current.c: Likewise.
* nptl/thrd_detach.c: Likewise.
* nptl/thrd_equal.c: Likewise.
* nptl/thrd_exit.c: Likewise.
* nptl/thrd_join.c: Likewise.
* nptl/thrd_priv.h: Likewise.
* nptl/thrd_sleep.c: Likewise.
* nptl/thrd_yield.c: Likewise.
* include/threads.h: Likewise.
The __libc_freeres framework does not extend to non-libc.so objects.
This causes problems in general for valgrind and mtrace detecting
unfreed objects in both libdl.so and libpthread.so. This change is
a pre-requisite to properly moving the malloc hooks out of malloc
since such a move now requires precise accounting of all allocated
data before destructors are run.
This commit adds a proper hook in libc.so.6 for both libdl.so and
for libpthread.so, this ensures that shm-directory.c which uses
freeit () to free memory is called properly. We also remove the
nptl_freeres hook and fall back to using weak-ref-and-check idiom
for a loaded libpthread.so, thus making this process similar for
all DSOs.
Lastly we follow best practice and use explicit free calls for
both libdl.so and libpthread.so instead of the generic hook process
which has undefined order.
Tested on x86_64 with no regressions.
Signed-off-by: DJ Delorie <dj@redhat.com>
Signed-off-by: Carlos O'Donell <carlos@redhat.com>
This patch renames the nptl-signals.h header to internal-signals.h.
On Linux the definitions and functions are not only NPTL related, but
used for other POSIX definitions as well (for instance SIGTIMER for
posix times, SIGSETXID for id functions, and signal block/restore
helpers) and since generic functions will be places and used in generic
implementation it makes more sense to decouple it from NPTL.
Checked on x86_64-linux-gnu.
* sysdeps/nptl/nptl-signals.h: Move to ...
* sysdeps/generic/internal-signals.h: ... here. Adjust internal
comments.
* sysdeps/unix/sysv/linux/internal-signals.h: Add include guards.
(__nptl_is_internal_signal): Rename to __is_internal_signal.
(__nptl_clear_internal_signals): Rename to __clear_internal_signals.
* sysdeps/unix/sysv/linux/raise.c: Adjust nptl-signal.h to
include-signals.h rename.
* nptl/pthreadP.h: Likewise.
* sysdeps/unix/sysv/linux/spawni.c (__spawni_child): Call
__is_internal_signal instead of __nptl_is_internal_signal.
This patch consolidates the pthread_join and gnu extensions to avoid
code duplication. The function pthread_join, pthread_tryjoin_np, and
pthread_timedjoin_np are now based on pthread_timedjoin_ex.
It also fixes some inconsistencies on ESRCH, EINVAL, EDEADLK handling
(where each implementation differs from each other) and also on
clenup handler (which now always use a CAS).
Checked on i686-linux-gnu and x86_64-linux-gnu.
* nptl/pthreadP.h (__pthread_timedjoin_np): Define.
* nptl/pthread_join.c (pthread_join): Use __pthread_timedjoin_np.
* nptl/pthread_tryjoin.c (pthread_tryjoin): Likewise.
* nptl/pthread_timedjoin.c (cleanup): Use CAS on argument setting.
(pthread_timedjoin_np): Define internal symbol and common code from
pthread_join.
* sysdeps/unix/sysv/linux/i386/lowlevellock.h (__lll_timedwait_tid):
Remove superflous checks.
* sysdeps/unix/sysv/linux/x86_64/lowlevellock.h (__lll_timedwait_tid):
Likewise.
Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
GCC 4.9 (the minimum current supported) emits an warning for universal
zero initializer ({0}) on ASSERT_PTHREAD_INTERNAL_SIZE:
pthread_attr_init.c: In function ‘__pthread_attr_init_2_1’:
pthread_attr_init.c:37:3: error: missing braces around initializer [-Werror=missing-braces]
ASSERT_PTHREAD_INTERNAL_SIZE (pthread_attr_t, struct pthread_attr);
^
pthread_attr_init.c:37:3: error: (near initialization for ‘(anonymous).__size’) [-Werror=missing-braces]
It is fact GCC BZ#53119 [1] fixed in later version (GCC5+). Since
current branch is closed and there is no indication it will be backports
(comment #20 in same bug report) this patch fixes by using a double
bracket to zero initialize the struct.
Checked on x86_64-linux-gnu with GCC 7 and GCC 4.9.
* nptl/pthreadP.h (ASSERT_PTHREAD_INTERNAL_SIZE): Add workarond for
-Wmissing-braces on GCC 4.9.
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53119
Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This patch adds a new build test to check for internal fields
offsets for user visible internal field. Although currently
the only field which is statically initialized to a non zero value
is pthread_mutex_t.__data.__kind value, the tests also check the
offset of __kind, __spins, __elision (if supported), and __list
internal member. A internal header (pthread-offset.h) is added
to each major ABI with the reference value.
Checked on x86_64-linux-gnu and with a build check for all affected
ABIs (aarch64-linux-gnu, alpha-linux-gnu, arm-linux-gnueabihf,
hppa-linux-gnu, i686-linux-gnu, ia64-linux-gnu, m68k-linux-gnu,
microblaze-linux-gnu, mips64-linux-gnu, mips64-n32-linux-gnu,
mips-linux-gnu, powerpc64le-linux-gnu, powerpc-linux-gnu,
s390-linux-gnu, s390x-linux-gnu, sh4-linux-gnu, sparc64-linux-gnu,
sparcv9-linux-gnu, tilegx-linux-gnu, tilegx-linux-gnu-x32,
tilepro-linux-gnu, x86_64-linux-gnu, and x86_64-linux-x32).
* nptl/pthreadP.h (ASSERT_PTHREAD_STRING,
ASSERT_PTHREAD_INTERNAL_OFFSET): New macro.
* nptl/pthread_mutex_init.c (__pthread_mutex_init): Add build time
checks for internal pthread_mutex_t offsets.
* sysdeps/aarch64/nptl/pthread-offsets.h
(__PTHREAD_MUTEX_NUSERS_OFFSET, __PTHREAD_MUTEX_KIND_OFFSET,
__PTHREAD_MUTEX_SPINS_OFFSET, __PTHREAD_MUTEX_ELISION_OFFSET,
__PTHREAD_MUTEX_LIST_OFFSET): New macro.
* sysdeps/alpha/nptl/pthread-offsets.h: Likewise.
* sysdeps/arm/nptl/pthread-offsets.h: Likewise.
* sysdeps/hppa/nptl/pthread-offsets.h: Likewise.
* sysdeps/i386/nptl/pthread-offsets.h: Likewise.
* sysdeps/ia64/nptl/pthread-offsets.h: Likewise.
* sysdeps/m68k/nptl/pthread-offsets.h: Likewise.
* sysdeps/microblaze/nptl/pthread-offsets.h: Likewise.
* sysdeps/mips/nptl/pthread-offsets.h: Likewise.
* sysdeps/nios2/nptl/pthread-offsets.h: Likewise.
* sysdeps/powerpc/nptl/pthread-offsets.h: Likewise.
* sysdeps/s390/nptl/pthread-offsets.h: Likewise.
* sysdeps/sh/nptl/pthread-offsets.h: Likewise.
* sysdeps/sparc/nptl/pthread-offsets.h: Likewise.
* sysdeps/tile/nptl/pthread-offsets.h: Likewise.
* sysdeps/x86_64/nptl/pthread-offsets.h: Likewise.
Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The new cond var implementation (ed19993b5b) removed all the
__ASSUME_{REQUEUE_PI,FUTEX_LOCK_PI} internal usage so there is no
need to keep defining it. This patch removes all USE_REQUEUE_PI
and __ASSUME_REQUEUE_PI. It is as follow up from BZ#18463.
Checked with a build for x86_64-linux-gnu, arm-linux-gnueabhf,
m68-linux-gnu, mips64-linux-gnu, and sparc64-linux-gnu.
* nptl/pthreadP.h (USE_REQUEUE_PI): Remove ununsed macro.
* sysdeps/unix/sysv/linux/arm/kernel-features.h
(__ASSUME_REQUEUE_PI): Likewise.
* sysdeps/unix/sysv/linux/kernel-features.h
(__ASSUME_REQUEUE_PI): Likewise.
* sysdeps/unix/sysv/linux/m68k/kernel-features.h
(__ASSUME_REQUEUE_PI): Likewise.
* sysdeps/unix/sysv/linux/mips/kernel-features.h
(__ASSUME_REQUEUE_PI): Likewise.
* sysdeps/unix/sysv/linux/sparc/kernel-features.h
(__ASSUME_REQUEUE_PI): Likewise.
This is a new implementation for condition variables, required
after http://austingroupbugs.net/view.php?id=609 to fix bug 13165. In
essence, we need to be stricter in which waiters a signal or broadcast
is required to wake up; this couldn't be solved using the old algorithm.
ISO C++ made a similar clarification, so this also fixes a bug in
current libstdc++, for example.
We can't use the old algorithm anymore because futexes do not guarantee
to wake in FIFO order. Thus, when we wake, we can't simply let any
waiter grab a signal, but we need to ensure that one of the waiters
happening before the signal is woken up. This is something the previous
algorithm violated (see bug 13165).
There's another issue specific to condvars: ABA issues on the underlying
futexes. Unlike mutexes that have just three states, or semaphores that
have no tokens or a limited number of them, the state of a condvar is
the *order* of the waiters. A waiter on a semaphore can grab a token
whenever one is available; a condvar waiter must only consume a signal
if it is eligible to do so as determined by the relative order of the
waiter and the signal.
Therefore, this new algorithm maintains two groups of waiters: Those
eligible to consume signals (G1), and those that have to wait until
previous waiters have consumed signals (G2). Once G1 is empty, G2
becomes the new G1. 64b counters are used to avoid ABA issues.
This condvar doesn't yet use a requeue optimization (ie, on a broadcast,
waking just one thread and requeueing all others on the futex of the
mutex supplied by the program). I don't think doing the requeue is
necessarily the right approach (but I haven't done real measurements
yet):
* If a program expects to wake many threads at the same time and make
that scalable, a condvar isn't great anyway because of how it requires
waiters to operate mutually exclusive (due to the mutex usage). Thus, a
thundering herd problem is a scalability problem with or without the
optimization. Using something like a semaphore might be more
appropriate in such a case.
* The scalability problem is actually at the mutex side; the condvar
could help (and it tries to with the requeue optimization), but it
should be the mutex who decides how that is done, and whether it is done
at all.
* Forcing all but one waiter into the kernel-side wait queue of the
mutex prevents/avoids the use of lock elision on the mutex. Thus, it
prevents the only cure against the underlying scalability problem
inherent to condvars.
* If condvars use short critical sections (ie, hold the mutex just to
check a binary flag or such), which they should do ideally, then forcing
all those waiter to proceed serially with kernel-based hand-off (ie,
futex ops in the mutex' contended state, via the futex wait queues) will
be less efficient than just letting a scalable mutex implementation take
care of it. Our current mutex impl doesn't employ spinning at all, but
if critical sections are short, spinning can be much better.
* Doing the requeue stuff requires all waiters to always drive the mutex
into the contended state. This leads to each waiter having to call
futex_wake after lock release, even if this wouldn't be necessary.
[BZ #13165]
* nptl/pthread_cond_broadcast.c (__pthread_cond_broadcast): Rewrite to
use new algorithm.
* nptl/pthread_cond_destroy.c (__pthread_cond_destroy): Likewise.
* nptl/pthread_cond_init.c (__pthread_cond_init): Likewise.
* nptl/pthread_cond_signal.c (__pthread_cond_signal): Likewise.
* nptl/pthread_cond_wait.c (__pthread_cond_wait): Likewise.
(__pthread_cond_timedwait): Move here from pthread_cond_timedwait.c.
(__condvar_confirm_wakeup, __condvar_cancel_waiting,
__condvar_cleanup_waiting, __condvar_dec_grefs,
__pthread_cond_wait_common): New.
(__condvar_cleanup): Remove.
* npt/pthread_condattr_getclock.c (pthread_condattr_getclock): Adapt.
* npt/pthread_condattr_setclock.c (pthread_condattr_setclock):
Likewise.
* npt/pthread_condattr_getpshared.c (pthread_condattr_getpshared):
Likewise.
* npt/pthread_condattr_init.c (pthread_condattr_init): Likewise.
* nptl/tst-cond1.c: Add comment.
* nptl/tst-cond20.c (do_test): Adapt.
* nptl/tst-cond22.c (do_test): Likewise.
* sysdeps/aarch64/nptl/bits/pthreadtypes.h (pthread_cond_t): Adapt
structure.
* sysdeps/arm/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/ia64/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/m68k/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/microblaze/nptl/bits/pthreadtypes.h (pthread_cond_t):
Likewise.
* sysdeps/mips/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/nios2/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/s390/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/sh/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/tile/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/unix/sysv/linux/alpha/bits/pthreadtypes.h (pthread_cond_t):
Likewise.
* sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h (pthread_cond_t):
Likewise.
* sysdeps/x86/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/nptl/internaltypes.h (COND_NWAITERS_SHIFT): Remove.
(COND_CLOCK_BITS): Adapt.
* sysdeps/nptl/pthread.h (PTHREAD_COND_INITIALIZER): Adapt.
* nptl/pthreadP.h (__PTHREAD_COND_CLOCK_MONOTONIC_MASK,
__PTHREAD_COND_SHARED_MASK): New.
* nptl/nptl-printers.py (CLOCK_IDS): Remove.
(ConditionVariablePrinter, ConditionVariableAttributesPrinter): Adapt.
* nptl/nptl_lock_constants.pysym: Adapt.
* nptl/test-cond-printers.py: Adapt.
* sysdeps/unix/sysv/linux/hppa/internaltypes.h (cond_compat_clear,
cond_compat_check_and_clear): Adapt.
* sysdeps/unix/sysv/linux/hppa/pthread_cond_timedwait.c: Remove file ...
* sysdeps/unix/sysv/linux/hppa/pthread_cond_wait.c
(__pthread_cond_timedwait): ... and move here.
* nptl/DESIGN-condvar.txt: Remove file.
* nptl/lowlevelcond.sym: Likewise.
* nptl/pthread_cond_timedwait.c: Likewise.
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_broadcast.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_signal.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_timedwait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_wait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i586/pthread_cond_broadcast.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i586/pthread_cond_signal.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i586/pthread_cond_timedwait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i586/pthread_cond_wait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i686/pthread_cond_broadcast.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i686/pthread_cond_signal.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i686/pthread_cond_timedwait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i686/pthread_cond_wait.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_broadcast.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_signal.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S: Likewise.
This patch fixes both sem_wait and sem_timedwait cancellation point for
uncontended case. In this scenario only atomics are involved and thus
the futex cancellable call is not issue and a pending cancellation signal
is not handled.
The fix is straighforward by calling pthread_testcancel is both function
start. Although it would be simpler to call CANCELLATION_P directly, I
decided to add an internal pthread_testcancel alias and use it to export
less internal implementation on such function. A possible change on
how pthread_testcancel is internally implemented would lead to either
continue to force use CANCELLATION_P or to adjust its every use.
GLIBC testcase also does have tests for uncontended cases, test-cancel12
and test-cancel14.c, however both are flawed by adding another
cancellation point just after thread pthread_cleanup_pop:
47 static void *
48 tf (void *arg)
49 {
50 pthread_cleanup_push (cleanup, NULL);
51
52 int e = pthread_barrier_wait (&bar);
53 if (e != 0 && e != PTHREAD_BARRIER_SERIAL_THREAD)
54 {
55 puts ("tf: 1st barrier_wait failed");
56 exit (1);
57 }
58
59 /* This call should block and be cancelable. */
60 sem_wait (&sem);
61
62 pthread_cleanup_pop (0);
63
64 puts ("sem_wait returned");
65
66 return NULL;
67 }
So sem_{timed}wait does not act on cancellation, pthread_cleanup_pop executes
'cleanup' and then 'puts' acts on cancellation. Since pthread_cleanup_pop
removed the clean-up handler, it will ran only once and thus it won't accuse
an error to indicate sem_wait has not acted on the cancellation signal.
This patch also fixes this behavior by removing the cancellation point 'puts'.
It also adds some cleanup on all sem_{timed}wait cancel tests.
It partially fixes BZ #18243. Checked on x86_64.
[BZ #18243]
* nptl/pthreadP.h (__pthread_testcancel): Add prototype and hidden_proto.
* nptl/pthread_testcancel.c (pthread_cancel): Add internal aliais
definition.
* nptl/sem_timedwait.c (sem_timedwait): Add cancellation check for
uncontended case.
* nptl/sem_wait.c (__new_sem_wait): Likewise.
* nptl/tst-cancel12.c (cleanup): Remove wrong cancellation point.
(tf): Fix check for uncontended case.
(do_test): Likewise.
* nptl/tst-cancel13.c (cleanup): Remove wrong cancellation point.
(tf): Fix check for uncontended case.
(do_test): Likewise.
* nptl/tst-cancel14.c (cleanup): Remove wrong cancellation point.
(tf): Fix check for uncontended case.
(do_test): Likewise.
* nptl/tst-cancel15.c (cleanup): Remove wrong cancellation point.
(tf): Fix check for uncontended case.
(do_test): Likewise.
and also powerpc64 and powerpc64le. See the discussion in the thread
below for details. This change reverts the problematic bits leaving
the added test in place and marking XFAIL in anticipation of fixing
the bug in the near future.
https://sourceware.org/ml/libc-alpha/2015-07/msg00141.html
[BZ #18435]
* nptl/pthreadP.h (pthread_cleanup_push, pthread_cleanup_pop):
Revert commit ed225df3ad.
* nptl/Makefile (test-xfail-tst-once5): Define.
the initialization routine to exit by throwing an exception.
Such an execution, termed exceptional, requires call_once to
propagate the exception to its caller. A program may contain
any number of exceptional executions but only one returning
execution (which, if it exists, must be the last execution
with the same once flag).
On POSIX systems such as Linux, std::call_once is implemented
in terms of pthread_once. However, as discussed in libstdc++
bug 66146 - "call_once not C++11-compliant on ppc64le," GLIBC's
pthread_once hangs when the initialization function exits by
throwing an exception on at least arm and ppc64 (though
apparently not on x86_64). This effectively prevents call_once
from conforming to the C++ requirements since there doesn't
appear to be a thread-safe way to work around this problem in
libstdc++.
This patch changes pthread_once to handle gracefully init
functions that exit by throwing exceptions. It was successfully
tested on ppc64, ppc64le, and x86_64.
[BZ #18435]
* nptl/Makefile: Add tst-once5.cc.
* nptl/pthreadP.h (pthread_cleanup_push, pthread_cleanup_pop):
Remove macro redefinitions.
* nptl/tst-once5.cc: New test.
If a call to the set*id functions fails in a multi-threaded program,
the abort introduced in commit 13f7fe35ae
was triggered.
We address by checking that all calls to set*id on all threads give
the same result, and only abort if we see success followed by failure
(or vice versa).
Add elision paths to the basic mutex locks.
The normal path has a check for RTM and upgrades the lock
to RTM when available. Trylocks cannot automatically upgrade,
so they check for elision every time.
We use a 4 byte value in the mutex to store the lock
elision adaptation state. This is separate from the adaptive
spin state and uses a separate field.
Condition variables currently do not support elision.
Recursive mutexes and condition variables may be supported at some point,
but are not in the current implementation. Also "trylock" will
not automatically enable elision unless some other lock call
has been already called on the lock.
This version does not use IFUNC, so it means every lock has one
additional check for elision. Benchmarking showed the overhead
to be negligible.
Add Enable/disable flags used internally
Extend the mutex initializers to have the fields needed for
elision. The layout stays the same, and this is not visible
to programs.
These changes are not exposed outside pthread
This patch introduces two new convenience functions to set the default
thread attributes used for creating threads. This allows a programmer
to set the default thread attributes just once in a process and then
run pthread_create without additional attributes.
There is nothing in the POSIX specification to disallow a
single-threaded program from cancelling itself, so we forcibly enable
multiple_threads to allow the next available cancellation point in the
thread to run.
Also added additional tests to cover various cancellation scenarios.
(__free_stack_cache): Removed. Change callers to call __free_stacks.
* init.c (nptl_freeres): New function.
(pthread_functions): Initialize ptr_freeres to nptl_freeres.
* pthreadP.h: Don't declare __free_stack_cache. Declare __free_stacks.
* sysdeps/pthread/unwind-forcedunwind.c (libgcc_s_handle): New
variable.
(pthread_cancel_init): Depend in libgcc_s_handle for decision to
load DSO. Assign last.
(__unwind_freeres): New function.
* allocatestack.c (__reclaim_stacks): Reset in_flight_stack later
for better debugging. No need to use stack_list_add here.
