[dpdk-dev] [PATCH v3 4/5] eal: prevent secondary process init while sending messages

Burakov, Anatoly anatoly.burakov at intel.com
Wed Feb 28 11:19:45 CET 2018


On 28-Feb-18 1:58 AM, Tan, Jianfeng wrote:
> Hi Anatoly,
> 
>> -----Original Message-----
>> From: Burakov, Anatoly
>> Sent: Tuesday, February 27, 2018 10:36 PM
>> To: dev at dpdk.org
>> Cc: Tan, Jianfeng
>> Subject: [PATCH v3 4/5] eal: prevent secondary process init while sending
>> messages
>>
>> Currently, it is possible to spin up a secondary process while
>> either sendmsg or request is in progress. Fix this by adding
>> directory locks during init, sendmsg and requests.
> 
> Could you give a more detailed example for this issue?
> 
> And why locking the directory can help?
> 
> Thanks,
> Jianfeng
> 

Consider this. You start a request. Since sending this out takes 
non-zero amount of time, and you're waiting for process to reply each 
time you send a message, there's a non-zero chance where contents of 
/var/run may change and another socket file may appear that wasn't there 
when we started sending out those messages.

This is simply making sending requests atomic, if you will. Honestly, i 
can't think of a situation where this might be a problem, but it just 
doesn't feel right, so i fixed it :)

-- 
Thanks,
Anatoly


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