[PATCH v2 2/2] y2038: Convert aio_suspend to support 64 bit time
Lukasz Majewski
lukma@denx.de
Tue Nov 17 23:01:34 GMT 2020
Hi Adhemerval,
> On 14/11/2020 18:45, Lukasz Majewski wrote:
> > The aio_suspend function has been converted to support 64 bit time.
> > It was also necessary to provide Linux specific copy of
> > aio_suspend.c to avoid problems on i686-gnu (i.e. HURD) port, which
> > is not providing pthread_cond_timedwait() supporting 64 bit time.
> >
> > This change uses:
> > - New __futex_reltimed_wait64 (instead of futex_reltimed_wait)
> > - New __futex_reltimed_wait_cancellable64
> > (instead of futex_reltimed_wait_cancellable)
> > from ./sysdeps/nptl/futex-helpers.h
> >
> > The aio_suspend() accepts relative timeout.
> >
> > The __aio_suspend() is supposed to be run on ports with __TIMESIZE
> > !=64 and __WORDSIZE==32. It internally utilizes
> > __aio_suspend_time64() and hence the conversion from 32 bit struct
> > timespec to 64 bit one is required.
> >
> > For ports supporting 64 bit time the __aio_suspend_time64() will be
> > used either via alias (to __aio_suspend when __TIMESIZE==64) or
> > redirection (when -D_TIME_BITS=64 is passed).
> >
> > Build tests:
> > ./src/scripts/build-many-glibcs.py glibcs
> >
> > ---
> > Changes for v2:
> > - Add missing -EOVERFLOW error handling for __futex_reltimed_wait64
> > and _futex_reltimed_wait_cancelable64
> >
> > Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
> > ---
> > include/aio.h | 8 +++
> > sysdeps/nptl/aio_misc.h | 4 +-
> > sysdeps/nptl/futex-internal.h | 93
> > +++++++++++++++++++++++++++ sysdeps/unix/sysv/linux/aio_suspend.c |
> > 41 +++++++++--- 4 files changed, 136 insertions(+), 10 deletions(-)
> >
> > diff --git a/include/aio.h b/include/aio.h
> > index 90c74f9951..c7f4233310 100644
> > --- a/include/aio.h
> > +++ b/include/aio.h
> > @@ -9,6 +9,14 @@ extern void __aio_init (const struct aioinit
> > *__init); lio_listio and we do not issue events for each individual
> > list element. */
> > #define LIO_NO_INDIVIDUAL_EVENT 128
> > +
> > +# if __TIMESIZE == 64
> > +# define __aio_suspend_time64 __aio_suspend
> > +# else
> > +extern int __aio_suspend_time64 (const struct aiocb *const list[],
> > int nent,
> > + const struct __timespec64
> > *timeout); +librt_hidden_proto (__aio_suspend_time64)
> > +# endif
> > #endif
> >
> > #endif
> > diff --git a/sysdeps/nptl/aio_misc.h b/sysdeps/nptl/aio_misc.h
> > index 3f195f4794..5c553cce56 100644
> > --- a/sysdeps/nptl/aio_misc.h
> > +++ b/sysdeps/nptl/aio_misc.h
> > @@ -45,10 +45,10 @@
> > do
> > \ {
> > \ if (cancel)
> > \
> > - status = futex_reltimed_wait_cancelable (
> > \
> > + status = __futex_reltimed_wait_cancelable64 (
> > \ (unsigned int *) futexaddr, oldval, timeout,
> > FUTEX_PRIVATE); \ else
> > \
> > - status = futex_reltimed_wait ((unsigned int *)
> > futexaddr, \
> > + status = __futex_reltimed_wait64 ((unsigned int *)
> > futexaddr, \ oldval, timeout, FUTEX_PRIVATE);
> > \ if (status != EAGAIN)
> > \ break;
> > \ diff --git
> > a/sysdeps/nptl/futex-internal.h b/sysdeps/nptl/futex-internal.h
> > index c27d0cdac8..1134ecfe88 100644 ---
> > a/sysdeps/nptl/futex-internal.h +++ b/sysdeps/nptl/futex-internal.h
> > @@ -609,4 +609,97 @@ __futex_clock_wait_bitset64 (int *futexp, int
> > val, clockid_t clockid, const struct __timespec64 *abstime,
> > int private) attribute_hidden;
> >
> > +static __always_inline int
> > +__futex_reltimed_wait64 (unsigned int* futex_word, unsigned int
> > expected,
> > + const struct __timespec64* reltime, int
> > private) +{
>
> The static inline function does not need to use double '__'.
Ok.
>
> > + int err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word,
> > + __lll_private_flag (FUTEX_WAIT,
> > private),
> > + expected, reltime);
> > +#ifndef __ASSUME_TIME64_SYSCALLS
> > + if (err == -ENOSYS)
> > + {
> > + if (in_time_t_range (reltime->tv_sec))
> > + {
> > + struct timespec ts32 = valid_timespec64_to_timespec
> > (*reltime); +
> > + err = INTERNAL_SYSCALL_CALL (futex, futex_word,
> > + __lll_private_flag
> > (FUTEX_WAIT,
> > +
> > private),
> > + expected, &ts32);
> > + }
> > + else
> > + err = -EOVERFLOW;
> > + }
> > +#endif
> > + switch (err)
> > + {
> > + case 0:
> > + case -EAGAIN:
> > + case -EINTR:
> > + case -ETIMEDOUT:
> > + case -EOVERFLOW: /* Passed relative timeout uses 64 bit
> > time_t type, but
> > + underlying kernel does not support 64 bit
> > time_t futex
> > + syscalls. */
> > + return -err;
> > +
> > + case -EFAULT: /* Must have been caused by a glibc or
> > application bug. */
> > + case -EINVAL: /* Either due to wrong alignment or due to the
> > timeout not
> > + being normalized. Must have been caused by a
> > glibc or
> > + application bug. */
> > + case -ENOSYS: /* Must have been caused by a glibc bug. */
> > + /* No other errors are documented at this time. */
> > + default:
> > + futex_fatal_error ();
> > + }
> > +}
> > +
> > +/* Like futex_reltimed_wait but is a POSIX cancellation point. */
> > +static __always_inline int
> > +__futex_reltimed_wait_cancelable64 (unsigned int* futex_word,
> > + unsigned int expected,
> > + const struct __timespec64*
> > reltime,
> > + int private)
>
> Same as before.
Ok.
>
> > +{
> > + int err = INTERNAL_SYSCALL_CANCEL (futex_time64, futex_word,
> > + __lll_private_flag
> > (FUTEX_WAIT, private),
> > + expected, reltime);
> > +#ifndef __ASSUME_TIME64_SYSCALLS
> > + if (err == -ENOSYS)
> > + {
> > + if (in_time_t_range (reltime->tv_sec))
> > + {
> > + struct timespec ts32 = valid_timespec64_to_timespec
> > (*reltime); +
> > + err = INTERNAL_SYSCALL_CANCEL (futex, futex_word,
> > + __lll_private_flag
> > (FUTEX_WAIT,
> > +
> > private),
> > + expected, &ts32);
> > + }
> > + else
> > + err = -EOVERFLOW;
> > + }
> > +#endif
> > + switch (err)
> > + {
> > + case 0:
> > + case -EAGAIN:
> > + case -EINTR:
> > + case -ETIMEDOUT:
> > + case -EOVERFLOW: /* Passed relative timeout uses 64 bit
> > time_t type, but
> > + underlying kernel does not support 64 bit
> > time_t futex
> > + syscalls. */
> > + return -err;
> > +
> > + case -EFAULT: /* Must have been caused by a glibc or
> > application bug. */
> > + case -EINVAL: /* Either due to wrong alignment or due to the
> > timeout not
> > + being normalized. Must have been caused by a
> > glibc or
> > + application bug. */
> > + case -ENOSYS: /* Must have been caused by a glibc bug. */
> > + /* No other errors are documented at this time. */
> > + default:
> > + futex_fatal_error ();
> > + }
> > +}
> > +
> > #endif /* futex-internal.h */
>
> We might revise this large inline functions later, specially for
> !__ASSUME_TIME64_SYSCALLS.
Ok.
> These would be used on GAI_MISC_WAIT, so
> it might be better to either export it to libpthread GLIBC_PRIVATE
> namespace or build futex-internal.c on librt (which will pull extra
> unused implementation).
Hmm... Another place which would require Y2038 tunning...
>
> Also, once GAI_MISC_WAIT y2038 supported is added we will probably
> need to remove the ununsed futex_reltimed_wait{_cancellable}.
Also the C preprocessor macro code from
sysdeps/nptl/lowlevellock-futex.h could be removed.
>
> > diff --git a/sysdeps/unix/sysv/linux/aio_suspend.c
> > b/sysdeps/unix/sysv/linux/aio_suspend.c index
> > ad03f13558..8ce7bfedb0 100644 ---
> > a/sysdeps/unix/sysv/linux/aio_suspend.c +++
> > b/sysdeps/unix/sysv/linux/aio_suspend.c @@ -94,7 +94,7 @@ cleanup
> > (void *arg) #ifdef DONT_NEED_AIO_MISC_COND
> > static int
> > __attribute__ ((noinline))
> > -do_aio_misc_wait (unsigned int *cntr, const struct timespec
> > *timeout) +do_aio_misc_wait (unsigned int *cntr, const struct
> > __timespec64 *timeout) {
> > int result = 0;
> >
> > @@ -105,8 +105,8 @@ do_aio_misc_wait (unsigned int *cntr, const
> > struct timespec *timeout) #endif
> >
> > int
> > -aio_suspend (const struct aiocb *const list[], int nent,
> > - const struct timespec *timeout)
> > +__aio_suspend_common64 (const struct aiocb *const list[], int nent,
> > + const struct __timespec64 *timeout)
> > {
> > if (__glibc_unlikely (nent < 0))
> > {
> > @@ -183,10 +183,10 @@ aio_suspend (const struct aiocb *const
> > list[], int nent, {
> > /* We have to convert the relative timeout value into an
> > absolute time value with pthread_cond_timedwait
> > expects. */
> > - struct timespec now;
> > - struct timespec abstime;
> > + struct __timespec64 now;
> > + struct __timespec64 abstime;
> >
> > - __clock_gettime (CLOCK_REALTIME, &now);
> > + __clock_gettime64 (CLOCK_REALTIME, &now);
> > abstime.tv_nsec = timeout->tv_nsec + now.tv_nsec;
> > abstime.tv_sec = timeout->tv_sec + now.tv_sec;
> > if (abstime.tv_nsec >= 1000000000)
> > @@ -195,8 +195,8 @@ aio_suspend (const struct aiocb *const list[],
> > int nent, abstime.tv_sec += 1;
> > }
> >
> > - result = pthread_cond_timedwait (&cond,
> > &__aio_requests_mutex,
> > - &abstime);
> > + result = __pthread_cond_timedwait64 (&cond,
> > &__aio_requests_mutex,
> > + &abstime);
> > }
> > #endif
> >
>
> The pthread_cond fallback is not needed on Linux, it defines
> DONT_NEED_AIO_MISC_COND which would use the futex calls directly.
The usage of DONT_NEED_AIO_MISC_COND seems to be a bit convoluted. It
mixes #include_next with some headers' dependencies.
However, It looks like I can leave the current implementation as is - I
don't need to adjust aio_suspend() (__aio_suspend_common64) when the
DONT_NEED_AIO_MISC_COND flag is NOT defined - "Linux" ports do define it.
I'm now testing such patch and will post it if it is OK.
>
> > @@ -250,4 +250,29 @@ aio_suspend (const struct aiocb *const list[],
> > int nent, return result;
> > }
> >
> > +int
> > +__aio_suspend_time64 (const struct aiocb *const list[], int nent,
> > + const struct __timespec64 *timeout)
> > +{
> > + return __aio_suspend_common64 (list, nent, timeout);
> > +}
> > +
> > +#if __TIMESIZE != 64
> > +librt_hidden_def (__aio_suspend_time64)
> > +
> > +int
> > +__aio_suspend(const struct aiocb *const list[], int nent,
> > + const struct timespec *timeout)
> > +{
> > + struct __timespec64 ts64;
> > +
> > + if (timeout != NULL)
> > + {
> > + ts64 = valid_timespec_to_timespec64 (*timeout);
> > + }
> > +
> > + return __aio_suspend_time64 (list, nent, timeout != NULL ? &ts64
> > : NULL); +}
> > +#endif
> > +weak_alias (__aio_suspend, aio_suspend)
> > weak_alias (aio_suspend, aio_suspend64)
> >
Best regards,
Lukasz Majewski
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de
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