linux-kernel - Re: [PATCH v2 1/1] eventfd: implementation of EFD

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Message-ID: <55F91DBE.90903@igel.co.jp>
Date:	Wed, 16 Sep 2015 16:43:58 +0900
From:	Damian Hobson-Garcia <dhobsong@...l.co.jp>
To:	Martin Sustrik <sustrik@...bpm.com>
Cc:	viro@...iv.linux.org.uk, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, linux-api@...r.kernel.org,
	netdev@...r.kernel.org, David.Laight@...lab.com
Subject: Re: [PATCH v2 1/1] eventfd: implementation of EFD_MASK flag

Hi Martin,

On 2015-09-16 3:51 PM, Martin Sustrik wrote:
> On 2015-09-16 08:27, Damian Hobson-Garcia wrote:
>>
>> Additionally, to provide a way to associate user-space state with eventfd
>> object, it allows to attach user-space data to the file descriptor.
> 
> The above paragraph is a leftover from the past. The functionality no
> longer exist.
> 
Oops, I forgot to delete that part. I'll get rid of it.

>>
>> The semantics of EFD_MASK are as follows:
>>
>> eventfd(2):
>>
>> If eventfd is created with EFD_MASK flag set, it is initialised in such a
>> way as to signal no events on the file descriptor when it is polled on.
>> The 'initval' argument is ignored.
>>
>> write(2):
>>
>> User is allowed to write only buffers containing the following structure:
>>
>> struct efd_mask {
>>   uint32_t events;
>> };
> 
> Is it worth having a struct here? Why not just uint32_t?
As it stands right now, no, the struct doesn't really add anything.
uint32_t should be just fine.
> 
> Martin

Damian
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