Re: [PATCH] [RFC] notify userspace about time changes

From: Kay Sievers
Date: Thu Aug 05 2010 - 18:40:31 EST

On Fri, Aug 6, 2010 at 00:34, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> On 08/05/2010 03:22 PM, Kay Sievers wrote:
>> I think that's really awkward interface, to pass file descriptor
>> numbers around and write them to magic sysfs files.
>> I would very much prefer a file that contains the current time, and
>> wakes up possible users with a POLL_ERR on changes caused by some
>> other process. That works very well for things like /proc/mounts, is
>> easy to get, and does not need a full page of weird instructions to
>> get stuff done. :)
> Okay, what's wrong with having a file descriptor that gets *written to*
> on a notification?

Because it needs documentation, and is just not needed for such a
simple thing, I think. Why would you want to write a fd number to a
magic file, which can be your fd right away, even passing you the data
on read().


Because normal files can not be poll()ed, and it's not that new data
has arrived, it just tells you to rewind and read it again. It's
commonly used:;a=commitdiff;h=5addc5dd8836aa061f6efc4a0d9ba6323726297a

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