From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: Florian Weimer <fweimer@redhat.com>, libc-alpha@sourceware.org
Subject: Re: [PATCH v8 1/8] nptl: Add C11 threads thrd_* functions
Date: Fri, 13 Jul 2018 10:18:47 -0300 [thread overview]
Message-ID: <38895177-c89b-40ae-9dbd-53768d3d73be@linaro.org> (raw)
In-Reply-To: <0ebcfb95-926d-b7a1-b762-7388f1e2b5d1@redhat.com>
On 13/07/2018 10:04, Florian Weimer wrote:
> On 07/13/2018 02:59 PM, Adhemerval Zanella wrote:
>>
>>
>> On 13/07/2018 06:45, Florian Weimer wrote:
>>> On 02/02/2018 06:04 PM, Adhemerval Zanella wrote:
>>>> 2. thrd_sleep uses nanosleep internal direct syscall to avoid clobbering
>>>> errno, to handle expected standard return codes, and to avoid making
>>>> the call a POSIX cancellation entrypoint.
>>>
>>> Isn't this inconsistent with the conditional variable wait and thread join functions, which are still cancellation points?
>>>
>>> On the other hand, a sleep function which is not a cancellation point may be useful.
>>
>> I am not sure which would be the best option to handle POSIX cancellation
>> with C11 threads with nptl implementation. Most straightforward option is
>> just use cancellation entrypoints as default, even though using thread
>> cancellation in C11 is UB (there is no defined way the use can get the
>> POSIX thread id from a C11 thread).
>
> That's not true. The POSIX thread ID is available using pthread_self on the thread itself, and that can be passed to another thread.
That is what I am not sure, if mixing POSIX semantic with C11 is really
defined by any standard (for instance, calling pthread_cancel with an
POSIX thread ID which was not created by pthread_create).
>
>> Another option is just disable cancellation by using non-cancellable
>> entry-points and/or explicit disable cancellation. For thrd_join is
>> just a matter to set on '__pthread_timedjoin_ex', but for
>> cnd_wait/cnd_timedwait we either need to explicit enable/disable or
>> add an option to __pthread_cond_wait_common to select whether to use
>> cancellable syscalls.
>
> From my point of view, the least surprising approach would be to make thrd_sleep a cancellation point to match nanosleep.
Right, I will change thrd_sleep to use a cancellation entrypoint. We
can evaluate the POSIX cancellation interaction with C11 threads in
next releases.
next prev parent reply other threads:[~2018-07-13 13:18 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-02 17:04 [PATCH v8 0/8] Add support for ISO C threads.h Adhemerval Zanella
2018-02-02 17:04 ` [PATCH v8 1/8] nptl: Add C11 threads thrd_* functions Adhemerval Zanella
2018-02-08 13:49 ` Gabriel F. T. Gomes
2018-02-09 10:56 ` Adhemerval Zanella
2018-02-26 12:28 ` Gabriel F. T. Gomes
2018-07-06 12:46 ` Florian Weimer
2018-07-10 19:26 ` Adhemerval Zanella
2018-07-11 15:49 ` Szabolcs Nagy
2018-07-11 16:24 ` Adhemerval Zanella
2018-07-12 12:18 ` Florian Weimer
2018-07-12 17:38 ` Adhemerval Zanella
2018-07-13 7:03 ` Florian Weimer
2018-07-12 16:46 ` Florian Weimer
2018-07-12 17:52 ` Adhemerval Zanella
2018-07-12 18:24 ` Florian Weimer
2018-07-12 19:19 ` Adhemerval Zanella
2018-07-12 19:26 ` Florian Weimer
2018-07-12 19:41 ` Adhemerval Zanella
2018-07-12 19:32 ` Adhemerval Zanella
2018-07-12 19:35 ` Florian Weimer
2018-07-12 19:43 ` Adhemerval Zanella
2018-07-13 9:45 ` Florian Weimer
2018-07-13 12:59 ` Adhemerval Zanella
2018-07-13 13:04 ` Florian Weimer
2018-07-13 13:18 ` Adhemerval Zanella [this message]
2018-07-13 13:21 ` Florian Weimer
2018-07-13 9:48 ` Florian Weimer
2018-07-25 7:20 ` Andreas Schwab
2018-07-25 7:38 ` Florian Weimer
2018-07-25 10:29 ` Joseph Myers
2018-02-02 17:04 ` [PATCH v8 2/8] nptl: Add C11 threads mtx_* functions Adhemerval Zanella
2018-07-06 12:51 ` Florian Weimer
2018-07-10 12:35 ` Adhemerval Zanella
2018-07-12 18:39 ` Florian Weimer
2018-07-12 20:30 ` Adhemerval Zanella
2018-07-12 20:38 ` Florian Weimer
2018-07-13 13:08 ` Adhemerval Zanella
2018-07-13 13:10 ` Florian Weimer
2018-07-24 12:04 ` Adhemerval Zanella
2018-07-24 16:04 ` Carlos O'Donell
2018-02-02 17:04 ` [PATCH v8 3/8] nptl: Add C11 threads call_once functions Adhemerval Zanella
2018-07-13 9:32 ` Florian Weimer
2018-02-02 17:04 ` [PATCH v8 4/8] nptl: Add C11 threads cnd_* functions Adhemerval Zanella
2018-02-02 17:04 ` [PATCH v8 5/8] nptl: Add C11 threads tss_* functions Adhemerval Zanella
2018-07-12 16:48 ` Florian Weimer
2018-07-12 20:32 ` Adhemerval Zanella
2018-07-12 20:37 ` Florian Weimer
2018-02-02 17:04 ` [PATCH v8 6/8] nptl: Add abilist symbols for C11 threads Adhemerval Zanella
2018-07-13 9:50 ` Florian Weimer
2018-07-13 15:49 ` Adhemerval Zanella
2018-07-13 17:49 ` Florian Weimer
2018-07-13 18:47 ` Adhemerval Zanella
2018-07-13 19:56 ` Florian Weimer
2018-07-13 21:09 ` Adhemerval Zanella
2018-07-14 13:50 ` Florian Weimer
2018-07-18 17:40 ` Joseph Myers
2018-07-18 20:02 ` Adhemerval Zanella
2018-07-18 21:19 ` Florian Weimer
2018-02-02 17:04 ` [PATCH v8 7/8] nptl: Add test cases for ISO " Adhemerval Zanella
2018-07-13 9:31 ` Florian Weimer
2018-07-13 13:10 ` Adhemerval Zanella
2018-07-13 13:11 ` Florian Weimer
2018-07-13 13:29 ` Adhemerval Zanella
2018-07-17 13:53 ` Adhemerval Zanella
2018-02-02 17:04 ` [PATCH v8 8/8] Add manual documentation for threads.h Adhemerval Zanella
2018-06-27 13:39 ` [PATCH v8 0/8] Add support for ISO C threads.h Adhemerval Zanella
2018-07-19 17:46 ` Adhemerval Zanella
2018-07-19 18:43 ` Carlos O'Donell
2018-07-19 19:12 ` Rical Jasan
2018-07-19 19:58 ` Adhemerval Zanella
2018-07-21 0:26 ` Rical Jasan
2018-07-21 2:11 ` Carlos O'Donell
2018-07-21 6:22 ` Rical Jasan
2018-07-21 13:40 ` Adhemerval Zanella
2018-07-19 21:26 ` Joseph Myers
2018-07-20 12:32 ` Adhemerval Zanella
2018-07-20 13:22 ` Rical Jasan
2018-07-20 13:54 ` Rical Jasan
2018-07-20 14:04 ` Carlos O'Donell
2018-07-20 15:02 ` [PATCH v8 0/8] Add support for ISO C threads.h [thrd_exit] Rical Jasan
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