linux-kernel - Re: [Patch 3/4] ipc/mqueue: strengthen checks on mqueue creation

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Date:	Tue, 01 May 2012 19:04:53 -0400
From:	KOSAKI Motohiro <kosaki.motohiro@...il.com>
To:	Doug Ledford <dledford@...hat.com>
CC:	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	sfr@...b.auug.org.au
Subject: Re: [Patch 3/4] ipc/mqueue: strengthen checks on mqueue creation

(5/1/12 7:02 PM), Doug Ledford wrote:
> On 5/1/2012 4:18 PM, KOSAKI Motohiro wrote:
>>>> But ENOMEM is more inaccurate. It almostly is used for kmalloc failure.
>>>
>>> I chose ENOMEM for that particular error because above there we have
>>> checked the passed in arguments to make sure that they don't violate our
>>> allowances for max message or max message size.  If we violate either of
>>> those items, we return EINVAL.  In this case, neither of the values is
>>> invalid, it's just that together they make an overly large allocation.
>>> I would see that as more helpful to a programmer than EINVAL when the
>>> values are within the maximums allowed.  At least with ENOMEM the
>>> programmer knows they have to reduce their combined message size and
>>> message count in order to get things working.
>>
>> Incorrect. When ENOMEM is returned, programmers can't know
>> which problem was happen 1) kernel has real memory starvation
>> or 2) queue limitation exceed was happen. The problem is, you
>> introduced new overloaded error code for avoiding overload error code.
>> It doesn't make sense. My question was, why can't you choose no
>> overload error code if you want accurate one?
>
> OK, then would EOVERFLOW suit things better?

I have no seen to any confusion source this. thank you.

then, ack all of this series.
  Acked-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>


>
> All this reminds me that when this is taken into Linus' kernel, we need
> to coordinate a man page update for the mq subsystem.


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