linux-kernel - Re: [RFC 1/6] bidi support: request dma_data

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <45B6115C.2010601@panasas.com>
Date:	Tue, 23 Jan 2007 15:45:00 +0200
From:	Benny Halevy <bhalevy@...asas.com>
To:	Muli Ben-Yehuda <muli@...ibm.com>,
	Boaz Harrosh <bharrosh@...asas.com>
CC:	Jens Axboe <jens.axboe@...cle.com>,
	Christoph Hellwig <hch@...radead.org>,
	Mike Christie <michaelc@...wisc.edu>,
	linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
	open-iscsi@...glegroups.com, Daniel.E.Messinger@...gate.com,
	Liran Schour <LIRANS@...ibm.com>
Subject: Re: [RFC 1/6] bidi support: request dma_data_direction

Muli Ben-Yehuda wrote:
> On Mon, Jan 22, 2007 at 01:21:28AM +0200, Boaz Harrosh wrote:
> 
>> - Introduce a new enum dma_data_direction data_dir member in struct request.
>>   and remove the RW bit from request->cmd_flag
> 
> Some architecture use 'enum dma_data_direction' and some 'int
> dma_data_direction'. The consensus was to move to int over
> time. Please use 'int dma_data_direction'.

That should be fine (although I'm not sure what made you go this way :)
Please see my reply to Douglas, proposing an enum req_io_direction
at the block layer and up which will provide a better enumeration
for our use.

>>
>> +static inline int dma_write_dir(enum dma_data_direction dir)
>> +{
>> +	return (dir == DMA_TO_DEVICE) || (dir == DMA_BIDIRECTIONAL);
>> +}
> 
> "write" can mean "write to device" or "write to memory", depending on
> context. Not exactly something which should be a generic
> helper. Rename to 'dma_to_device(int dir)'?

much better. thanks!

> 
>> +static inline int dma_uni_dir(enum dma_data_direction dir)
>> +{
>> +	return (dir == DMA_TO_DEVICE) || (dir == DMA_FROM_DEVICE) ||
>> +	       (dir == DMA_NONE);
>> +}
> 
> While this doesn't look very useful. Why is "DMA_NONE" a uni-dir? I
> suggest replacing this with an open coded (dir != DMA_BIDIRECTIONAL).

The idea was to be resilient to invalid values. (dir != DMA_BIDIRECTIONAL)
is fine of course, but I'd add a BUG_ON such as (dir < 0 || dir > DMA_BIDIRECTIONAL)

Benny
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/