[ovs-dev] [PATCH] ovs-lib.in:Add process name checking when start ovs service

Lichunhe lichunhe at huawei.com
Fri Aug 1 01:09:31 UTC 2014


>-----Original Message-----
>From: Ben Pfaff [mailto:blp at nicira.com]
>Sent: Friday, August 01, 2014 8:19 AM
>To: Lichunhe
>Cc: dev at openvswitch.org; Qianhuibin (Huibin QIAN, Euler)
>Subject: Re: [ovs-dev] [PATCH] ovs-lib.in:Add process name checking when start
>ovs service
>
>On Wed, Jul 30, 2014 at 02:22:50PM +0800, lichunhe at huawei.com wrote:
>> From: Chunhe Li <lichunhe at huawei.com>
>>
>> Only check wheather is daemon pid exist is not enough, becasue the pid
>> which store in pidfile maybe assign to another process by OS. So it
>> will checking failed for pid exist, but the starting process which own
>> the pid is not the ovs daemon.
>>
>> Signed-off-by: Chunhe Li <lichunhe at huawei.com>
>> Signed-off-by: wuyunfei <wuyunfei at huawei.com>
>
>Does this solve a problem you observed in practice?
>
>There are at least two other ways that one could verify that the pid is actually
>the process we expect.  One is to look at /proc/$pid/comm or /proc/$pid/exe.
>The other is to verify that the process holds the lock on the pidfile (which all OVS
>daemons do).  These approaches might be more reliable than "pidof": instead
>of checking that some process with the given name exists, they check attributes
>of that particular process.
>
>What are your thoughts?

Yes, we use this patch solve a problem, and the scenario is that the server which runs the daemon 
is cold reset, the "pidfile" is not cleared. When the server starts, the left $pid which stores in "pidfile"
has been assigned to "ovs_workq" kernel process, and then the ovs-vswitchd starts to check the $pid,
finds it exist and exit.

These approaches which you list are better than my provided. Do you want me to send another patch?
Or you could do it yourself.

Thanks.
Chunhe.



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