From: Arnd Bergmann <arnd@arndb.de>
To: Ido Schimmel <idosch@idosch.org>
Cc: Andrew Lunn <andrew@lunn.ch>, Aya Levin <ayal@mellanox.com>,
"David S. Miller" <davem@davemloft.net>,
Jiri Pirko <jiri@mellanox.com>,
Networking <netdev@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [net] devlink: Add method for time-stamp on reporter's dump
Date: Thu, 22 Aug 2019 21:11:42 +0200 [thread overview]
Message-ID: <CAK8P3a2mQHvQKzWSKofBPdzFDTZq9oJkDHqR2PR85Hswocy45g@mail.gmail.com> (raw)
In-Reply-To: <20190822174037.GA18030@splinter>
On Thu, Aug 22, 2019 at 7:40 PM Ido Schimmel <idosch@idosch.org> wrote:
> On Thu, Aug 22, 2019 at 04:06:35PM +0200, Andrew Lunn wrote:
> > On Thu, Aug 22, 2019 at 11:17:51AM +0300, Aya Levin wrote:
> > > When setting the dump's time-stamp, use ktime_get_real in addition to
> > > jiffies. This simplifies the user space implementation and bypasses
> > > some inconsistent behavior with translating jiffies to current time.
> >
> > Is this year 2038 safe? I don't know enough about this to answer the
> > question myself.
>
> Good point. 'struct timespec' is not considered year 2038 safe and
> unfortunately I recently made the mistake of using it to communicate
> timestamps to user space over netlink. :/ The code is still in net-next,
> so I will fix it while I can.
>
> Arnd, would it be acceptable to use 'struct __kernel_timespec' instead?
The in-kernel representation should just use 'timespec64' if you need
separate seconds and nanoseconds, you can convert that to
__kernel_timespec while copying to user space.
However, please consider two other points:
- for simplicity, the general recommendation is to use 64-bit nanoseconds
without separate seconds for timestamps
- instead of CLOCK_REALTIME, you could use CLOCK_MONOTONIC
timestamps that are not affected by clock_settime() or leap second jumps.
Arnd
prev parent reply other threads:[~2019-08-22 19:12 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-22 8:17 [net] devlink: Add method for time-stamp on reporter's dump Aya Levin
2019-08-22 14:06 ` Andrew Lunn
2019-08-22 17:40 ` Ido Schimmel
2019-08-22 19:11 ` Arnd Bergmann [this message]
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