From: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
To: Eric Rannaud <eric.rannaud@gmail.com>,
linux-api@vger.kernel.org, linux-man@vger.kernel.org
Cc: mtk.manpages@gmail.com, Aleksa Sarai <asarai@suse.de>
Subject: Re: clock_settime(2) error for non-settable clocks
Date: Thu, 26 Mar 2020 09:37:40 +0100 [thread overview]
Message-ID: <a225bae5-e342-fee4-b7fa-c3093ca52fa0@gmail.com> (raw)
In-Reply-To: <CA+zRj8U5_NaY4ZQXj9r=f58KcO3pq5k9HZt9KxRYHnOOk=e1WQ@mail.gmail.com>
Eric,
On 3/20/20 7:02 PM, Eric Rannaud wrote:
> If clock_id is a valid clock on the system (i.e. it can be passed to
> clock_gettime(2)), clock_settime(clock_id, &ts) sets errno to, either:
>
> - EINVAL if CONFIG_POSIX_TIMERS is not enabled (kernel/posix-stubs.c);
> - EINVAL if CONFIG_POSIX_TIMERS is enabled (kernel/posix-timers.c)
> and the k_clock has no set function (e.g. CLOCK_BOOTTIME);
> - EACCES for dynamic posix clock devices that lack F_WRITE
> (kernel/posix-time.c);
> - EOPNOTSUPP for dynamic posix clock devices that have F_WRITE but
> don't have a clock_settime op.
> - EOPNOTSUPP for drivers/ptp/ptp_kvm.c (they provide a clock_settime
> op that returns -EOPNOTSUPP directly, rather than opt to leave
> clock_settime NULL which would do the same thing, see previous point).
>
> The manpage for clock_settime(2) is not very clear:
>
> EINVAL The clk_id specified is not supported on this system.
>
> EPERM clock_settime() does not have permission to set the clock indi‐
> cated.
>
> To me, the manpage reads like EPERM should be expected when trying to
> set a clock that is not settable.
>
> Should we update the manpage to more fully explain the range of
> possible errors or instead try to have more consistent errors? For
> syscalls, what's the backward-compatibility contract for errno values?
A man-pages patch would be most appropriate. Would you be able to put
something together?
Thanks,
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
next prev parent reply other threads:[~2020-03-26 8:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-20 18:02 clock_settime(2) error for non-settable clocks Eric Rannaud
2020-03-21 3:56 ` Aleksa Sarai
2020-03-26 8:37 ` Michael Kerrisk (man-pages) [this message]
2020-03-29 20:49 ` Michael Kerrisk (man-pages)
2020-04-02 11:48 ` Michael Kerrisk (man-pages)
2020-04-02 14:23 ` [PATCH 1/1] clock_getres.2: dynamic POSIX clock devices can return other errors Eric Rannaud
2020-04-02 19:55 ` Michael Kerrisk (man-pages)
2020-04-02 20:06 ` Eric Rannaud
2020-04-02 20:19 ` Michael Kerrisk (man-pages)
2020-04-02 20:49 ` Eric Rannaud
2020-04-02 20:50 ` Eric Rannaud
2020-04-03 7:02 ` Michael Kerrisk (man-pages)
2020-04-03 16:42 ` Eric Rannaud
2020-04-20 11:13 ` Michael Kerrisk (man-pages)
2020-04-02 14:29 ` clock_settime(2) error for non-settable clocks Eric Rannaud
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