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From: Glen Turner <glen.turner@aarnet.edu.au>
To: Tim Hockin <thockin@hockin.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: PATCH: report NGROUPS_MAX via a sysctl (read-only)
Date: Wed, 25 Feb 2004 11:29:27 +1030	[thread overview]
Message-ID: <1077670767.24730.51.camel@andromache> (raw)
In-Reply-To: <20040220071028.GA4948@hockin.org>

On Fri, 2004-02-20 at 17:40, Tim Hockin wrote:

> Well, really I don't see how apps would want to use it in any way that was
> correct.

The mere existence of the value means it can be used correctly
in application code for sanity checking.

eg:
   assert(list_length(group_list) < ngroups_max());
   list_append(&group_list, group);

An application might also use it to automatically
size data structure details, such as the parameters of
a hash function.

  h = hash_create(ngroups_max());

Returning INT_MAX for NGROUPS_MAX isn't wrong, but you
then can't blame user space for making inefficient choices
if the kernel limit is actually smaller.

Cheers,
Glen



  reply	other threads:[~2004-02-25  1:00 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-02-20  2:39 PATCH: report NGROUPS_MAX via a sysctl (read-only) Tim Hockin
2004-02-20  5:30 ` Andrew Morton
2004-02-20  6:35   ` Tim Hockin
2004-02-20  6:47     ` Andrew Morton
2004-02-20  7:10       ` Tim Hockin
2004-02-25  0:59         ` Glen Turner [this message]
2004-02-25  1:14           ` Tim Hockin
2004-02-25  7:32             ` Ulrich Drepper

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