[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.


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