From: Lukasz Majewski <lukma@denx.de>
To: Joseph Myers <joseph@codesourcery.com>,
Paul Eggert <eggert@cs.ucla.edu>,
Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: Alistair Francis <alistair23@gmail.com>,
Arnd Bergmann <arnd@arndb.de>,
Alistair Francis <alistair.francis@wdc.com>,
GNU C Library <libc-alpha@sourceware.org>,
Florian Weimer <fweimer@redhat.com>,
Carlos O'Donell <carlos@redhat.com>,
Stepan Golosunov <stepan@golosunov.pp.ru>,
Andreas Schwab <schwab@suse.de>, Zack Weinberg <zackw@panix.com>,
Jeff Law <law@redhat.com>
Subject: Re: [PATCH v2 2/3] Y2038: nptl: Provide futex_abstimed_wait64 supporting 64 bit time
Date: Tue, 29 Sep 2020 18:55:58 +0200 [thread overview]
Message-ID: <20200929185558.28c20479@jawa> (raw)
In-Reply-To: <20200919130759.31916-2-lukma@denx.de>
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Dear Community,
> This is the helper function, which uses struct __timespec64
> to provide 64 bit absolute time to futex syscalls.
>
> The aim of this function is to move convoluted pre-processor
> macro code from sysdeps/nptl/lowlevellock-futex.h to C
> function in futex-internal.c
>
> The futex_abstimed_wait64 function has been put into a separate
> file on the purpose - to avoid issues apparent on the m68k
> architecture related to small number of available registers (there
> is not enough registers to put all necessary arguments in them if
> the above function would be added to futex-internal.h with
> __always_inline attribute).
>
> Additional precautions for m68k port have been taken - the
> futex-internal.c file will be compiled with -fno-inline flag.
>
Do we have more comments regarding this patch? Or shall I pull it to
-master?
> ---
> Changes for v2:
> - Handle the case when *abstime pointer is NULL
> ---
> sysdeps/nptl/futex-internal.c | 70
> +++++++++++++++++++++++++++ sysdeps/nptl/futex-internal.h |
> 6 +++ sysdeps/unix/sysv/linux/m68k/Makefile | 2 +
> 3 files changed, 78 insertions(+)
>
> diff --git a/sysdeps/nptl/futex-internal.c
> b/sysdeps/nptl/futex-internal.c index 3366aac162..3211b4c94f 100644
> --- a/sysdeps/nptl/futex-internal.c
> +++ b/sysdeps/nptl/futex-internal.c
> @@ -45,6 +45,29 @@ __futex_abstimed_wait_cancelable32 (unsigned int*
> futex_word, abstime != NULL ? &ts32 : NULL,
> NULL /* Unused. */,
> FUTEX_BITSET_MATCH_ANY); }
> +
> +static int
> +__futex_abstimed_wait32 (unsigned int* futex_word,
> + unsigned int expected, clockid_t clockid,
> + const struct __timespec64* abstime,
> + int private)
> +{
> + struct timespec ts32;
> +
> + if (abstime != NULL && ! in_time_t_range (abstime->tv_sec))
> + return -EOVERFLOW;
> +
> + unsigned int clockbit = (clockid == CLOCK_REALTIME) ?
> + FUTEX_CLOCK_REALTIME : 0;
> + int op = __lll_private_flag (FUTEX_WAIT_BITSET | clockbit,
> private); +
> + if (abstime != NULL)
> + ts32 = valid_timespec64_to_timespec (*abstime);
> +
> + return INTERNAL_SYSCALL_CALL (futex, futex_word, op, expected,
> + abstime != NULL ? &ts32 : NULL,
> + NULL /* Unused. */,
> FUTEX_BITSET_MATCH_ANY); +}
> #endif
>
> int
> @@ -97,3 +120,50 @@ __futex_abstimed_wait_cancelable64 (unsigned int*
> futex_word, futex_fatal_error ();
> }
> }
> +
> +int
> +__futex_abstimed_wait64 (unsigned int* futex_word, unsigned int
> expected,
> + clockid_t clockid,
> + const struct __timespec64* abstime, int
> private) +{
> + unsigned int clockbit;
> + int err;
> +
> + /* Work around the fact that the kernel rejects negative timeout
> values
> + despite them being valid. */
> + if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))
> + return ETIMEDOUT;
> +
> + if (! lll_futex_supported_clockid(clockid))
> + return EINVAL;
> +
> + clockbit = (clockid == CLOCK_REALTIME) ? FUTEX_CLOCK_REALTIME : 0;
> + int op = __lll_private_flag (FUTEX_WAIT_BITSET | clockbit,
> private); +
> + err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word, op,
> expected,
> + abstime, NULL /* Unused. */,
> + FUTEX_BITSET_MATCH_ANY);
> +#ifndef __ASSUME_TIME64_SYSCALLS
> + if (err == -ENOSYS)
> + err = __futex_abstimed_wait32 (futex_word, expected,
> + clockid, abstime, private);
> +#endif
> + switch (err)
> + {
> + case 0:
> + case -EAGAIN:
> + case -EINTR:
> + case -ETIMEDOUT:
> + return -err;
> +
> + case -EFAULT: /* Must have been caused by a glibc or application
> bug. */
> + case -EINVAL: /* Either due to wrong alignment, unsupported
> + clockid 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 ();
> + }
> +}
> diff --git a/sysdeps/nptl/futex-internal.h
> b/sysdeps/nptl/futex-internal.h index 7f3910ad98..1ba0d61938 100644
> --- a/sysdeps/nptl/futex-internal.h
> +++ b/sysdeps/nptl/futex-internal.h
> @@ -529,4 +529,10 @@ __futex_abstimed_wait_cancelable64 (unsigned
> int* futex_word, const struct __timespec64* abstime,
> int private) attribute_hidden;
>
> +int
> +__futex_abstimed_wait64 (unsigned int* futex_word, unsigned int
> expected,
> + clockid_t clockid,
> + const struct __timespec64* abstime,
> + int private) attribute_hidden;
> +
> #endif /* futex-internal.h */
> diff --git a/sysdeps/unix/sysv/linux/m68k/Makefile
> b/sysdeps/unix/sysv/linux/m68k/Makefile index be40fae68a..65164c5752
> 100644 --- a/sysdeps/unix/sysv/linux/m68k/Makefile
> +++ b/sysdeps/unix/sysv/linux/m68k/Makefile
> @@ -21,3 +21,5 @@ sysdep-dl-routines += dl-static
> sysdep-others += lddlibc4
> install-bin += lddlibc4
> endif
> +
> +CFLAGS-futex-internal.c += -fno-inline
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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next prev parent reply other threads:[~2020-09-29 16:56 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-19 13:07 [PATCH v2 1/3] nptl: futex: Move __NR_futex_time64 alias to beginning of futex-internal.h Lukasz Majewski
2020-09-19 13:07 ` [PATCH v2 2/3] Y2038: nptl: Provide futex_abstimed_wait64 supporting 64 bit time Lukasz Majewski
2020-09-21 17:00 ` Alistair Francis
2020-09-29 16:55 ` Lukasz Majewski [this message]
2020-09-30 11:52 ` Adhemerval Zanella
2020-09-30 12:47 ` Lukasz Majewski
2020-09-30 12:58 ` Andreas Schwab
2020-09-30 13:17 ` Lukasz Majewski
2020-09-30 13:14 ` Adhemerval Zanella
2020-09-30 13:39 ` Lukasz Majewski
2020-09-30 14:06 ` Lukasz Majewski
2020-09-19 13:07 ` [PATCH v2 3/3] y2038: nptl: Convert pthread_rwlock_{clock|timed}{rd|wr}lock to support " Lukasz Majewski
2020-09-29 16:56 ` Lukasz Majewski
2020-09-30 11:59 ` Adhemerval Zanella
2020-09-30 13:12 ` Lukasz Majewski
2020-09-30 13:19 ` Adhemerval Zanella
2020-10-02 12:15 ` Lukasz Majewski
2020-10-02 13:51 ` Adhemerval Zanella
2020-09-29 16:55 ` [PATCH v2 1/3] nptl: futex: Move __NR_futex_time64 alias to beginning of futex-internal.h Lukasz Majewski
2020-09-29 18:12 ` Adhemerval Zanella
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