Re: [Xen-devel] Zero-sized reads from XenBus block

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

El 2/3/16 a les 17:13, Wei Liu ha escrit:
> CC Linux kernel and FreeBSD maintainers.
> 
> On Wed, Mar 02, 2016 at 12:29:26AM +0300, Sergei Lebedev wrote:
>> Hi list,
>>
>> I’m not sure if this is the expected behaviour, but it seems zero-sized 
>> reads from /dev/xen/xenbus block. Here’s sample code in Python
>>
>>     import os
>>     
>>     fd = os.open("/dev/xen/xenbus", os.O_RDWR)
>>     os.read(fd, 0)  # Blocks.
>>
>> The issue is not language-specific, similar code in C blocks as well.

I've tested your code on FreeBSD (after replacing /dev/xen/xenbus with
/dev/xen/xenstore), and it doesn't block there. AFAICT this is because
0-size reads never get to the device "read" routine on FreeBSD, or else
it would block.

Roger.


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