so it gets shared by nptl and htl. Also add htl versions of thrd_current and
thrd_yield.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
See https://bugzilla.redhat.com/show_bug.cgi?id=1653942
This test depends on the kernel's assignment of memory regions, but
running under ld.so explicitly changes those assignments, sometimes
sufficiently to cause the test to fail (esp with address space
randomization).
The easiest way to "fix" the test, is to run it the way the user would
- without ld.so. Running it in a container does that.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Since commit a3cc4f48e9 ("Remove
--as-needed configure test."), --as-needed support is no longer
optional.
The macros are not much shorter and do not provide documentary
value, either, so this commit removes them.
This patch adds a new generic __pthread_rwlock_arch_t definition meant
to be used by new ports. Its layout mimics the current usage on some
64 bits ports and it allows some ports to use the generic definition.
The arch __pthread_rwlock_arch_t definition is moved from
pthreadtypes-arch.h to another arch-specific header (struct_rwlock.h).
Also the static intialization macro for pthread_rwlock_t is set to use
an arch defined on (__PTHREAD_RWLOCK_INITIALIZER) which simplifies its
implementation.
The default pthread_rwlock_t layout differs from current ports with:
1. Internal layout is the same for 32 bits and 64 bits.
2. Internal flag is an unsigned short so it should not required
additional padding to align for word boundary (if it is the case
for the ABI).
Checked with a build on affected abis.
Change-Id: I776a6a986c23199929d28a3dcd30272db21cd1d0
The current way of defining the common mutex definition for POSIX and
C11 on pthreadtypes-arch.h (added by commit 06be6368da) is
not really the best options for newer ports. It requires define some
misleading flags that should be always defined as 0
(__PTHREAD_COMPAT_PADDING_MID and __PTHREAD_COMPAT_PADDING_END), it
exposes options used solely for linuxthreads compat mode
(__PTHREAD_MUTEX_USE_UNION and __PTHREAD_MUTEX_NUSERS_AFTER_KIND), and
requires newer ports to explicit define them (adding more boilerplate
code).
This patch adds a new default __pthread_mutex_s definition meant to
be used by newer ports. Its layout mimics the current usage on both
32 and 64 bits ports and it allows most ports to use the generic
definition. Only ports that use some arch-specific definition (such
as hardware lock-elision or linuxthreads compat) requires specific
headers.
For 32 bit, the generic definitions mimic the other 32-bit ports
of using an union to define the fields uses on adaptive and robust
mutexes (thus not allowing both usage at same time) and by using a
single linked-list for robust mutexes. Both decisions seemed to
follow what recent ports have done and make the resulting
pthread_mutex_t/mtx_t object smaller.
Also the static intialization macro for pthread_mutex_t is set to use
a macro __PTHREAD_MUTEX_INITIALIZER where the architecture can redefine
in its struct_mutex.h if it requires additional fields to be
initialized.
Checked with a build on affected abis.
Change-Id: I30a22c3e3497805fd6e52994c5925897cffcfe13
Checked on x86_64-linux-gnu and powerpc64le-linux-gnu. I also checked
the libpthread.so .gnu.version_d entries for every ABI affected and
all of them contains the required versions (including for architectures
which exports __nanosleep with a different version).
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Passing NULL as the timeout parameter to pthread_timedjoin_np has resulted
in it behaving like pthread_join for a long time. Since that is now the
documented behaviour, we ought to test that both it and the new
pthread_clockjoin_np support it.
Checked on x86_64-linux-gnu.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Introduce pthread_clockjoin_np as a version of pthread_timedjoin_np that
accepts a clockid_t parameter to indicate which clock the timeout should be
measured against. This mirrors the recently-added POSIX-proposed "clock"
wait functions.
Checked on x86_64-linux-gnu.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Add:
int pthread_rwlock_clockrdlock (pthread_rwlock_t *rwlock,
clockid_t clockid,
const struct timespec *abstime)
and:
int pthread_rwlock_clockwrlock (pthread_rwlock_t *rwlock,
clockid_t clockid,
const struct timespec *abstime)
which behave like pthread_rwlock_timedrdlock and
pthread_rwlock_timedwrlock respectively, except they always measure
abstime against the supplied clockid. The functions currently support
CLOCK_REALTIME and CLOCK_MONOTONIC and return EINVAL if any other
clock is specified.
* sysdeps/nptl/pthread.h: Add pthread_rwlock_clockrdlock and
pthread_wrlock_clockwrlock.
* nptl/Makefile: Build pthread_rwlock_clockrdlock.c and
pthread_rwlock_clockwrlock.c.
* nptl/pthread_rwlock_clockrdlock.c: Implement
pthread_rwlock_clockrdlock.
* nptl/pthread_rwlock_clockwrlock.c: Implement
pthread_rwlock_clockwrlock.
* nptl/pthread_rwlock_common.c (__pthread_rwlock_rdlock_full): Add
clockid parameter and verify that it indicates a supported clock on
entry so that we fail even if it doesn't end up being used. Pass
that clock on to futex_abstimed_wait when necessary.
(__pthread_rwlock_wrlock_full): Likewise.
* nptl/pthread_rwlock_rdlock.c: (__pthread_rwlock_rdlock): Pass
CLOCK_REALTIME to __pthread_rwlock_rdlock_full even though it won't
be used because there's no timeout.
* nptl/pthread_rwlock_wrlock.c (__pthread_rwlock_wrlock): Pass
CLOCK_REALTIME to __pthread_rwlock_wrlock_full even though it won't
be used because there is no timeout.
* nptl/pthread_rwlock_timedrdlock.c (pthread_rwlock_timedrdlock):
Pass CLOCK_REALTIME to __pthread_rwlock_rdlock_full since abstime
uses that clock.
* nptl/pthread_rwlock_timedwrlock.c (pthread_rwlock_timedwrlock):
Pass CLOCK_REALTIME to __pthread_rwlock_wrlock_full since abstime
uses that clock.
* sysdeps/unix/sysv/linux/aarch64/libpthread.abilist (GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/alpha/libpthread.abilist (GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/arm/libpthread.abilist (GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/csky/libpthread.abilist (GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/hppa/libpthread.abilist (GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/i386/libpthread.abilist (GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/ia64/libpthread.abilist (GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/m68k/coldfire/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/m68k/m680x0/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/microblaze/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/mips/mips32/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/mips/mips64/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/nios2/libpthread.abilist (GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/riscv/rv64/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/s390/s390-64/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/sh/libpthread.abilist (GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc64/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/x86_64/64/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/x86_64/x32/libpthread.abilist
(GLIBC_2.30): Likewise.
* nptl/tst-abstime.c (th): Add pthread_rwlock_clockrdlock and
pthread_rwlock_clockwrlock timeout tests to match the existing
pthread_rwlock_timedrdloock and pthread_rwlock_timedwrlock tests.
* nptl/tst-rwlock14.c (do_test): Likewise.
* nptl/tst-rwlock6.c Invent verbose_printf macro, and use for
ancillary output throughout. (tf): Accept thread_args structure so
that rwlock, a clockid and function name can be passed to the
thread. (do_test_clock): Rename from do_test. Accept clockid
parameter to specify test clock. Use the magic clockid value of
CLOCK_USE_TIMEDLOCK to indicate that pthread_rwlock_timedrdlock and
pthread_rwlock_timedwrlock should be tested, otherwise pass the
specified clockid to pthread_rwlock_clockrdlock and
pthread_rwlock_clockwrlock. Use xpthread_create and xpthread_join.
(do_test): Call do_test_clock to test each clockid in turn.
* nptl/tst-rwlock7.c: Likewise.
* nptl/tst-rwlock9.c (writer_thread, reader_thread): Accept
thread_args structure so that the (now int) thread number, the
clockid and the function name can be passed to the thread.
(do_test_clock): Renamed from do_test. Pass the necessary
thread_args when creating the reader and writer threads. Use
xpthread_create and xpthread_join.
(do_test): Call do_test_clock to test each clockid in turn.
* manual/threads.texi: Add documentation for
pthread_rwlock_clockrdlock and pthread_rwlock_clockwrclock.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Add:
int pthread_cond_clockwait (pthread_cond_t *cond,
pthread_mutex_t *mutex,
clockid_t clockid,
const struct timespec *abstime)
which behaves just like pthread_cond_timedwait except it always measures
abstime against the supplied clockid. Currently supports CLOCK_REALTIME
and
CLOCK_MONOTONIC and returns EINVAL if any other clock is specified.
Includes feedback from many others. This function was originally
proposed[1] as pthread_cond_timedwaitonclock_np, but The Austin Group
preferred the new name.
* nptl/Makefile: Add tst-cond26 and tst-cond27
* nptl/Versions (GLIBC_2.30): Add pthread_cond_clockwait
* sysdeps/nptl/pthread.h: Likewise
* nptl/forward.c: Add __pthread_cond_clockwait
* nptl/forward.c: Likewise
* nptl/pthreadP.h: Likewise
* sysdeps/nptl/pthread-functions.h: Likewise
* nptl/pthread_cond_wait.c (__pthread_cond_wait_common): Add
clockid parameter and comment describing why we don't need to
check
its value. Use that value when calling
futex_abstimed_wait_cancelable rather than reading the clock
from
the flags. (__pthread_cond_wait): Pass unused clockid parameter.
(__pthread_cond_timedwait): Read clock from flags and pass it to
__pthread_cond_wait_common. (__pthread_cond_clockwait): Add new
function with weak alias from pthread_cond_clockwait.
* sysdeps/mach/hurd/i386/libpthread.abilist (GLIBC_2.30):
* Likewise.
* sysdeps/unix/sysv/linux/aarch64/libpthread.abilist
* (GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/alpha/libpthread.abilist (GLIBC_2.30):
* Likewise.
* sysdeps/unix/sysv/linux/arm/libpthread.abilist (GLIBC_2.30):
* Likewise.
* sysdeps/unix/sysv/linux/csky/libpthread.abilist (GLIBC_2.30):
* Likewise.
* sysdeps/unix/sysv/linux/hppa/libpthread.abilist (GLIBC_2.30):
* Likewise.
* sysdeps/unix/sysv/linux/i386/libpthread.abilist (GLIBC_2.30):
* Likewise.
* sysdeps/unix/sysv/linux/ia64/libpthread.abilist (GLIBC_2.30):
* Likewise.
* sysdeps/unix/sysv/linux/m68k/coldfire/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/m68k/m680x0/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/microblaze/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/mips/mips32/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/mips/mips64/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/nios2/libpthread.abilist (GLIBC_2.30):
* Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/riscv/rv64/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/s390/s390-64/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/sh/libpthread.abilist (GLIBC_2.30):
* Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc64/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/x86_64/64/libpthread.abilist
(GLIBC_2.30): Likewise.
* sysdeps/unix/sysv/linux/x86_64/x32/libpthread.abilist
(GLIBC_2.30): Likewise.
* nptl/tst-cond11.c (run_test): Support testing
pthread_cond_clockwait too by using a special magic
CLOCK_USE_ATTR_CLOCK value to determine whether to call
pthread_cond_timedwait or pthread_cond_clockwait. (do_test):
Pass
CLOCK_USE_ATTR_CLOCK for existing tests, and add new tests using
all combinations of CLOCK_MONOTONIC and CLOCK_REALTIME.
* ntpl/tst-cond26.c: New test for passing unsupported and
* invalid
clocks to pthread_cond_clockwait.
* nptl/tst-cond27.c: Add test similar to tst-cond5.c, but using
struct timespec and pthread_cond_clockwait.
* manual/threads.texi: Document pthread_cond_clockwait. The
* comment
was provided by Carlos O'Donell.
[1] https://sourceware.org/ml/libc-alpha/2015-07/msg00193.html
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
With commit f0b2132b35 ("ld.so:
Support moving versioned symbols between sonames [BZ #24741]"), the
dynamic linker will find the definition of vfork in libc and binds
a vfork reference to that symbol, even if the soname in the version
reference says that the symbol should be located in libpthread.
As a result, the forwarder (whether it's IFUNC-based or a duplicate
of the libc implementation) is no longer necessary.
On older architectures, a placeholder symbol is required, to make sure
that the GLIBC_2.1.2 symbol version does not go away, or is turned in
to a weak symbol definition by the link editor. (The symbol version
needs to preserved so that the symbol coverage check in
elf/dl-version.c does not fail for old binaries.)
mips32 is an outlier: It defined __vfork@@GLIBC_2.2, but the
baseline is GLIBC_2.0. Since there are other @@GLIBC_2.2 symbols,
the placeholder symbol is not needed there.
Don't run nptl/tst-eintr1 by normal make check because it can spuriously
break testing on various linux kernels. (Currently this affects the
aarch64 glibc buildbot machine which regularly fails and loses test
results.)
[BZ #24537]
* nptl/Makefile: Move tst-eintr1 to xtests.
This patch removes CLOCK_THREAD_CPUTIME_ID and CLOCK_PROCESS_CPUTIME_ID support
from clock_gettime and clock_settime generic implementation. For Linux, kernel
already provides supports through the syscall and Hurd HTL lacks
__pthread_clock_gettime and __pthread_clock_settime internal implementation.
As described in clock_gettime man-page [1] on 'Historical note for SMP
system', implementing CLOCK_{THREAD,PROCESS}_CPUTIME_ID with timer registers
is error-prone and susceptible to timing and accurary issues that the libc
can not deal without kernel support.
This allows removes unused code which, however, still incur in some runtime
overhead in thread creation (the struct pthread cpuclock_offset
initialization).
If hurd eventually wants to support them it should either either implement as
a kernel facility (or something related due its architecture) or in system
specific implementation.
Checked on aarch64-linux-gnu, x86_64-linux-gnu, and i686-linux-gnu. I also
checked on a i686-gnu build.
* nptl/Makefile (libpthread-routines): Remove pthread_clock_gettime and
pthread_clock_settime.
* nptl/pthreadP.h (__find_thread_by_id): Remove prototype.
* elf/dl-support.c [!HP_TIMING_NOAVAIL] (_dl_cpuclock_offset): Remove.
(_dl_non_dynamic_init): Remove _dl_cpuclock_offset setting.
* elf/rtld.c (_dl_start_final): Likewise.
* nptl/allocatestack.c (__find_thread_by_id): Remove function.
* sysdeps/generic/ldsodefs.h [!HP_TIMING_NOAVAIL] (_dl_cpuclock_offset):
Remove.
* sysdeps/mach/hurd/dl-sysdep.c [!HP_TIMING_NOAVAIL]
(_dl_cpuclock_offset): Remove.
* nptl/descr.h (struct pthread): Rename cpuclock_offset to
cpuclock_offset_ununsed.
* nptl/nptl-init.c (__pthread_initialize_minimal_internal): Remove
cpuclock_offset set.
* nptl/pthread_create.c (START_THREAD_DEFN): Likewise.
* sysdeps/nptl/fork.c (__libc_fork): Likewise.
* nptl/pthread_clock_gettime.c: Remove file.
* nptl/pthread_clock_settime.c: Likewise.
* sysdeps/unix/clock_gettime.c (hp_timing_gettime): Remove function.
[HP_TIMING_AVAIL] (realtime_gettime): Remove CLOCK_THREAD_CPUTIME_ID
and CLOCK_PROCESS_CPUTIME_ID support.
* sysdeps/unix/clock_settime.c (hp_timing_gettime): Likewise.
[HP_TIMING_AVAIL] (realtime_gettime): Likewise.
* sysdeps/posix/clock_getres.c (hp_timing_getres): Likewise.
[HP_TIMING_AVAIL] (__clock_getres): Likewise.
* sysdeps/unix/clock_nanosleep.c (CPUCLOCK_P, INVALID_CLOCK_P):
Likewise.
(__clock_nanosleep): Remove CPUCLOCK_P and INVALID_CLOCK_P usage.
[1] http://man7.org/linux/man-pages/man2/clock_gettime.2.html
Patch ce7eb0e903 ("nptl: Cleanup cancellation macros") changed the
join sequence for internal common __pthread_timedjoin_ex to use the
new macro lll_wait_tid. The idea was this macro would issue the
cancellable futex operation depending whether the timeout is used or
not. However if a timeout is used, __lll_timedwait_tid is called and
it is not a cancellable entrypoint.
This patch fixes it by simplifying the code in various ways:
- Instead of adding the cancellation handling on __lll_timedwait_tid,
it moves the generic implementation to pthread_join_common.c (called
now timedwait_tid with some fixes to use the correct type for pid).
- The llvm_wait_tid macro is removed, along with its replication on
x86_64, i686, and sparc arch-specific lowlevellock.h.
- sparc32 __lll_timedwait_tid is also removed, since the code is similar
to generic one.
- x86_64 and i386 provides arch-specific __lll_timedwait_tid which is
also removed since they are similar in functionality to generic C code
and there is no indication it is better than compiler generated code.
New tests, tst-join8 and tst-join9, are provided to check if
pthread_timedjoin_np acts as a cancellation point.
Checked on x86_64-linux-gnu, i686-linux-gnu, sparcv9-linux-gnu, and
aarch64-linux-gnu.
[BZ #24215]
* nptl/Makefile (lpthread-routines): Remove lll_timedwait_tid.
(tests): Add tst-join8 tst-join9.
* nptl/lll_timedwait_tid.c: Remove file.
* sysdeps/sparc/sparc32/lll_timedwait_tid.c: Likewise.
* sysdeps/unix/sysv/linux/i386/lll_timedwait_tid.c: Likewise.
* sysdeps/sysv/linux/x86_64/lll_timedwait_tid.c: Likewise.
* nptl/pthread_join_common.c (timedwait_tid): New function.
(__pthread_timedjoin_ex): Act as cancellation entrypoint is block
is set.
* nptl/tst-join5.c (thread_join): New function.
(tf1, tf2, do_test): Use libsupport and add pthread_timedjoin_np
check.
* nptl/tst-join8.c: New file.
* nptl/tst-join9.c: Likewise.
* sysdeps/nptl/lowlevellock-futex.h (lll_futex_wait_cancel,
lll_futex_timed_wait_cancel): Add generic macros.
* sysdeps/nptl/lowlevellock.h (__lll_timedwait_tid, lll_wait_tid):
Remove definitions.
* sysdeps/unix/sysv/linux/i386/lowlevellock.h: Likewise.
* sysdeps/unix/sysv/linux/sparc/lowlevellock.h: Likewise.
* sysdeps/unix/sysv/linux/x86_64/lowlevellock.h: Likewise.
* sysdeps/sparc/sparc32/lowlevellock.c (__lll_timedwait_tid):
Remove function.
* sysdeps/unix/sysv/linux/i386/lowlevellock.S (__lll_timedwait_tid):
Likewise.
* sysdeps/unix/sysv/linux/x86_64/lowlevellock.S: Likewise.
* sysdeps/unix/sysv/linux/lowlevellock-futex.h
(lll_futex_timed_wait_cancel): New macro.
The clone.S patch fixes 2 elfutils testsuite unwind failures, where the
backtrace gets stuck repeating __thread_start until we hit the backtrace
limit. This was confirmed by building and installing a patched glibc and
then building elfutils and running its testsuite.
Unfortunately, the testcase isn't working as expected and I don't know why.
The testcase passes even when my clone.S patch is not installed. The testcase
looks logically similarly to the elfutils testcases that are failing. Maybe
there is a subtle difference in how the glibc unwinding works versus the
elfutils unwinding? I don't have good gdb pthread support yet, so I haven't
found a way to debug this. Anyways, I don't know if the testcase is useful or
not. If the testcase isn't useful then maybe the clone.S patch is OK without
a testcase?
Jim
[BZ #24040]
* elf/Makefile (CFLAGS-tst-unwind-main.c): Add -DUSE_PTHREADS=0.
* elf/tst-unwind-main.c: If USE_PTHEADS, include pthread.h and error.h
(func): New.
(main): If USE_PTHREADS, call pthread_create to run func. Otherwise
call func directly.
* nptl/Makefile (tests): Add tst-unwind-thread.
(CFLAGS-tst-unwind-thread.c): Define.
* nptl/tst-unwind-thread.c: New file.
* sysdeps/unix/sysv/linux/riscv/clone.S (__thread_start): Mark ra
as undefined.
For a full analysis of both the pthread_rwlock_tryrdlock() stall
and the pthread_rwlock_trywrlock() stall see:
https://sourceware.org/bugzilla/show_bug.cgi?id=23844#c14
In the pthread_rwlock_trydlock() function we fail to inspect for
PTHREAD_RWLOCK_FUTEX_USED in __wrphase_futex and wake the waiting
readers.
In the pthread_rwlock_trywrlock() function we write 1 to
__wrphase_futex and loose the setting of the PTHREAD_RWLOCK_FUTEX_USED
bit, again failing to wake waiting readers during unlock.
The fix in the case of pthread_rwlock_trydlock() is to check for
PTHREAD_RWLOCK_FUTEX_USED and wake the readers.
The fix in the case of pthread_rwlock_trywrlock() is to only write
1 to __wrphase_futex if we installed the write phase, since all other
readers would be spinning waiting for this step.
We add two new tests, one exercises the stall for
pthread_rwlock_trywrlock() which is easy to exercise, and one exercises
the stall for pthread_rwlock_trydlock() which is harder to exercise.
The pthread_rwlock_trywrlock() test fails consistently without the fix,
and passes after. The pthread_rwlock_tryrdlock() test fails roughly
5-10% of the time without the fix, and passes all the time after.
Signed-off-by: Carlos O'Donell <carlos@redhat.com>
Signed-off-by: Torvald Riegel <triegel@redhat.com>
Signed-off-by: Rik Prohaska <prohaska7@gmail.com>
Co-authored-by: Torvald Riegel <triegel@redhat.com>
Co-authored-by: Rik Prohaska <prohaska7@gmail.com>
In the read lock function (__pthread_rwlock_rdlock_full) there was a
code path which would fail to reload __readers while waiting for
PTHREAD_RWLOCK_RWAITING to change. This failure to reload __readers
into a local value meant that various conditionals used the old value
of __readers and with only two threads left it could result in an
indefinite stall of one of the readers (waiting for PTHREAD_RWLOCK_RWAITING
to go to zero, but it never would).
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>
