Some futex-internal calls require additional check for EOVERFLOW (as
indicated by [1] [2] [3]). For both mutex and rwlock code, EOVERFLOW is
handle as ETIMEDOUT; since it indicate to the caller that the blocking
operation could not be issued.
For mutex it avoids a possible issue where PTHREAD_MUTEX_ROBUST_* might
assume EOVERFLOW indicate futex has succeed, and for PTHREAD_MUTEX_PP_*
it avoid a potential busy infinite loop. For rwlock and semaphores, it
also avoids potential busy infinite loops.
Checked on x86_64-linux-gnu and i686-linux-gnu, although EOVERFLOW
won't be possible with current usage (since all timeouts on 32-bit
architectures with 32-bit time_t support will be in the range of
32-bit time_t).
[1] https://sourceware.org/pipermail/libc-alpha/2020-November/120079.html
[2] https://sourceware.org/pipermail/libc-alpha/2020-November/120080.html
[3] https://sourceware.org/pipermail/libc-alpha/2020-November/120127.html
The pthread_rwlock_clockrdlock, pthread_rwlock_clockwrlock,
pthread_rwlock_timedrdlock and pthread_rwlock_timedwrlock have been converted
to support 64 bit time.
This change uses new futex_abstimed_wait64 function in
./sysdeps/nptl/futex-helpers.c, which uses futex_time64 where possible.
The pthread_rwlock_{clock|timed}{rd|wr}lock only accepts absolute time.
Moreover, there is no need to check for NULL passed as *abstime pointer to the
syscalls as those calls have exported symbols marked with __nonull attribute
for abstime.
For systems with __TIMESIZE != 64 && __WORDSIZE == 32:
- Conversions between 64 bit time to 32 bit are necessary
- Redirection to pthread_rwlock_{clock|timed}{rd|wr}lock will provide support
for 64 bit time
Build tests:
./src/scripts/build-many-glibcs.py glibcs
Run-time tests:
- Run specific tests on ARM/x86 32bit systems (qemu):
https://github.com/lmajewski/meta-y2038 and run tests:
https://github.com/lmajewski/y2038-tests/commits/master
Above tests were performed with Y2038 redirection applied as well as without
to test the proper usage of both __pthread_rwlock_{clock|timed}{rd|wr}lock64
and __pthread_rwlock_{clock|timed}{rd|wr}lock.
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
The valid_nanoseconds () static inline function has been introduced to
check if nanoseconds value is in the correct range - greater or equal to
zero and less than 1000000000.
The explicit #include <time.h> has been added to files where it was
missing.
The __syscall_slong_t type for ns has been used to avoid issues on x32.
Tested with:
- scripts/build-many-glibcs.py
- make PARALLELMFLAGS="-j12" && make PARALLELMFLAGS="-j12" xcheck on x86_64
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>
As recommended by the comments in the implementations of
pthread_rwlock_timedrdlock and pthread_rwlock_timedwrlock, let's move
the timeout validity checks into the corresponding pthread_rwlock_rdlock_full
and pthread_rwlock_wrlock_full functions. Since these functions may be
called with abstime == NULL, an extra check for that is necessary too.
* nptl/pthread_rwlock_common.c (__pthread_rwlock_rdlock_full):
Check validity of abstime parameter.
(__pthread_rwlock_rwlock_full): Likewise.
* nptl/pthread_rwlock_timedrdlock.c
* (pthread_rwlock_timedrdlock):
Remove check for validity of abstime parameter.
* nptl/pthread_rwlock_timedwrlock.c
* (pthread_rwlock_timedwrlock):
Likewise.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
In preparation for adding POSIX clockwait variants of timedwait functions,
add a clockid_t parameter to futex_abstimed_wait functions and pass
CLOCK_REALTIME from all callers for the time being.
Replace lll_futex_timed_wait_bitset with lll_futex_clock_wait_bitset
which takes a clockid_t parameter rather than the magic clockbit.
* sysdeps/nptl/lowlevellock-futex.h,
sysdeps/unix/sysv/linux/lowlevellock-futex.h: Replace
lll_futex_timed_wait_bitset with lll_futex_clock_wait_bitset that
takes a clockid rather than a special clockbit.
* sysdeps/nptl/lowlevellock-futex.h: Add
lll_futex_supported_clockid so that client functions can check
whether their clockid parameter is valid even if they don't
ultimately end up calling lll_futex_clock_wait_bitset.
* sysdeps/nptl/futex-internal.h,
sysdeps/unix/sysv/linux/futex-internal.h
(futex_abstimed_wait, futex_abstimed_wait_cancelable): Add
clockid_t parameter to indicate which clock the absolute time
passed should be measured against. Pass that clockid onto
lll_futex_clock_wait_bitset. Add invalid clock as reason for
returning -EINVAL.
* sysdeps/nptl/futex-internal.h,
sysdeps/unix/sysv/linux/futex-internal.h: Introduce
futex_abstimed_supported_clockid so that client functions can check
whether their clockid parameter is valid even if they don't
ultimately end up calling futex_abstimed_wait.
* nptl/pthread_cond_wait.c (__pthread_cond_wait_common): Remove
code to calculate relative timeout for
__PTHREAD_COND_CLOCK_MONOTONIC_MASK and just pass CLOCK_MONOTONIC
or CLOCK_REALTIME as required to futex_abstimed_wait_cancelable.
* nptl/pthread_rwlock_common (__pthread_rwlock_rdlock_full)
(__pthread_wrlock_full), nptl/sem_waitcommon (do_futex_wait): Pass
additional CLOCK_REALTIME to futex_abstimed_wait_cancelable.
* nptl/pthread_mutex_timedlock.c (__pthread_mutex_timedlock):
Switch to lll_futex_clock_wait_bitset and pass CLOCK_REALTIME
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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).
Without this fix, the rwlock can fail to execute the explicit hand-over
in certain cases (e.g., empty critical sections that switch quickly between
read and write phases). This can then lead to errors in how __wrphase_futex
is accessed, which in turn can lead to deadlocks.
