Re: [PATCH 1/2 v4] ahci add "em_buffer" attribute for AHCI hosts

[Tejun Heo <tj@kernel.org>]

Hello,

On 04/23/2010 04:47 AM, Harry Zhang wrote:
>> Oh, the PAGE_SIZE limit comes from the way sysfs attributes are
>> implemented.  The kernel buffer sysfs uses is PAGE_SIZE so
>> reads/writes can't be larger than that.  If you write past PAGE_SIZE
>> from show, you'll corrupt someone else's memory.
> Yes, I know that. I just think the EM read buffer size should not larger
> than the PAGE_SIZE in common, and thus, should not break the sysfs
> attributes r/w buffer limitation. Anyway, I will shorten the comment.

Oh I see.

>> It probably would be better to use ata_port_printk() and
>> printk_ratelimit() the message.
>
> OK. I could not determine which is better. I think the EM buffer is
> belong to the host rather than a port, so I chose the "dev_printk".
> BTW, should this be a warning or an error?

The buffer is per ATA port, so I think it would be better to use
ata_port_printk().  Hmmm... as the read will succeed anyway with
truncated message body, maybe warning is better?

Thanks.

-- 
tejun