From: Arnd Bergmann <arnd@arndb.de>
To: "André Almeida" <andrealmeid@collabora.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Darren Hart <dvhart@infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Collabora kernel ML <kernel@collabora.com>,
Gabriel Krisman Bertazi <krisman@collabora.com>,
Linux API <linux-api@vger.kernel.org>,
GNU C Library <libc-alpha@sourceware.org>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Arnd Bergmann <arnd@arndb.de>,
Alistair Francis <alistair.francis@wdc.com>
Subject: Re: [PATCH v2 20/22] selftests: futex: Test sys_futex_waitv() timeout
Date: Tue, 9 Nov 2021 14:05:11 +0100 [thread overview]
Message-ID: <CAK8P3a3T4qmZvags28bibibsyLBBLjsRQTGJqanLdcergxQTXQ@mail.gmail.com> (raw)
In-Reply-To: <51bbfe74-33f6-bb92-3ce8-a22e4185820b@collabora.com>
On Tue, Nov 9, 2021 at 1:52 PM André Almeida <andrealmeid@collabora.com> wrote:
> Às 08:18 de 09/11/21, Vasily Gorbik escreveu:
> > On Thu, Sep 23, 2021 at 02:11:09PM -0300, André Almeida wrote:
> >> Test if the futex_waitv timeout is working as expected, using the
> >> supported clockid options.
> >
> >> + /* futex_waitv with CLOCK_MONOTONIC */
> >> + if (futex_get_abs_timeout(CLOCK_MONOTONIC, &to, timeout_ns))
> >> + return RET_FAIL;
> >> + res = futex_waitv(&waitv, 1, 0, &to, CLOCK_MONOTONIC);
> >> + test_timeout(res, &ret, "futex_waitv monotonic", ETIMEDOUT);
> >> +
> >> + /* futex_waitv with CLOCK_REALTIME */
> >> + if (futex_get_abs_timeout(CLOCK_REALTIME, &to, timeout_ns))
> >> + return RET_FAIL;
> >> + res = futex_waitv(&waitv, 1, 0, &to, CLOCK_REALTIME);
> >> + test_timeout(res, &ret, "futex_waitv realtime", ETIMEDOUT);
> >
> > Hi André,
> >
> > when built with -m32 and run as compat this two futex_waitv calls hang
> > on x86 and s390 (noticed while wiring up futex_waitv). The rest of the
> > futex selftests pass. This suggests some common compat issue? Any ideas?
>
> The issue is that futex_waitv() only accepts struct timespec that uses
> 64bit members. When using -m32, glibc will give you a 32bit timespec,
> thus the timeout won't wort. Someday glibc will provide 64bit timespec
> to 32bit userspace, given that this is affected by y2038 bug.
I think in the latest glibc you should be able to pass -D_TIME_BITS=64 to
the compiler to get the correct definition. Unfortunately, this only works
for simple test cases, but breaks if you call any interfaces from another
(non-glibc) library that depend on a particular time_t definition.
Alistair Francis also recently posted a set of helpers for the old futex()
call to make that easier to use from applications regardless of the libc
interface. I think it would be good to have this for futex_waitv() as well.
Arnd
next prev parent reply other threads:[~2021-11-09 13:05 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-23 17:10 [PATCH v2 00/22] futex: splitup and waitv syscall André Almeida
2021-09-23 17:10 ` [PATCH v2 01/22] futex: Move to kernel/futex/ André Almeida
2021-09-23 17:10 ` [PATCH v2 02/22] futex: Split out syscalls André Almeida
2021-09-23 17:10 ` [PATCH v2 03/22] futex: Rename {,__}{,un}queue_me() André Almeida
2021-09-23 17:10 ` [PATCH v2 04/22] futex: Rename futex_wait_queue_me() André Almeida
2021-09-23 17:10 ` [PATCH v2 05/22] futex: Rename: queue_{,un}lock() André Almeida
2021-09-23 17:10 ` [PATCH v2 06/22] futex: Rename __unqueue_futex() André Almeida
2021-09-23 17:10 ` [PATCH v2 07/22] futex: Rename hash_futex() André Almeida
2021-09-23 17:10 ` [PATCH v2 08/22] futex: Rename: {get,cmpxchg}_futex_value_locked() André Almeida
2021-09-23 17:10 ` [PATCH v2 09/22] futex: Split out PI futex André Almeida
2021-09-23 17:10 ` [PATCH v2 10/22] futex: Rename: hb_waiter_{inc,dec,pending}() André Almeida
2021-09-23 17:11 ` [PATCH v2 11/22] futex: Rename: match_futex() André Almeida
2021-09-23 17:11 ` [PATCH v2 12/22] futex: Rename mark_wake_futex() André Almeida
2021-09-23 17:11 ` [PATCH v2 13/22] futex: Split out requeue André Almeida
2021-09-23 17:11 ` [PATCH v2 14/22] futex: Split out wait/wake André Almeida
2021-09-23 17:11 ` [PATCH v2 15/22] futex: Simplify double_lock_hb() André Almeida
2021-09-23 17:11 ` [PATCH v2 16/22] futex: Implement sys_futex_waitv() André Almeida
2021-10-06 11:50 ` Peter Zijlstra
2021-10-06 13:48 ` Zack Weinberg
2021-10-07 9:08 ` Peter Zijlstra
2021-10-07 13:27 ` Steven Rostedt
2021-09-23 17:11 ` [PATCH v2 17/22] futex,x86: Wire up sys_futex_waitv() André Almeida
2021-09-23 17:11 ` [PATCH v2 18/22] futex,arm: " André Almeida
2021-09-23 17:11 ` [PATCH v2 19/22] selftests: futex: Add sys_futex_waitv() test André Almeida
2021-09-23 17:11 ` [PATCH v2 20/22] selftests: futex: Test sys_futex_waitv() timeout André Almeida
2021-11-09 11:18 ` Vasily Gorbik
2021-11-09 12:52 ` André Almeida
2021-11-09 13:00 ` Adhemerval Zanella
2021-11-09 13:05 ` Arnd Bergmann [this message]
2021-09-23 17:11 ` [PATCH v2 21/22] selftests: futex: Test sys_futex_waitv() wouldblock André Almeida
2021-09-23 17:11 ` [PATCH v2 22/22] futex2: Documentation: Document sys_futex_waitv() uAPI André Almeida
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