[libvirt] [PATCH v5 3/3] libvirtd: fix crash on termination

[John Ferlan]

On 12/14/2017 06:58 AM, Nikolay Shirokovskiy wrote:
> Hi, all.
> 
> I looked over thread for this particular patch again and found resolution is we:
> 
> 1. make a more sane cleanup order in libvirtd's main function (already done by [1]).
> 2. rewrite linked series [2] by introducing event loop closing callback (ok)
> 
> But there is no resolution on this patch itself if I am not mistaken and
> it is not pushed too.
> 
> LINKS
> 
> [1] [PATCH 0/5] libvirtd: Adjustments to startup and cleanup processing
> https://www.redhat.com/archives/libvir-list/2017-November/msg00293.html

The cover letter of this essentially states the cleanup is an
alternative based upon the review of "this" series' 3/3 patch (IOW: this
patch).

So I agree w/ Erik - the (last) memory strand that I have left on this
indicates that the virHashRemoveAll isn't necessary in virNetDaemonClose
because we've properly order the cleanup with the new patch 4 from [1].

> 
> [2] [PATCH 0/4] libvirtd: fix hang on termination in qemu driver
> https://www.redhat.com/archives/libvir-list/2017-October/msg01134.html
> 

I responded to this series' cover letter with:

https://www.redhat.com/archives/libvir-list/2017-November/msg00455.html

in order to attempt to move the conversations found in "this" series to
that series rather than clouding "this" series with information
belonging to that series.

So the question *now* is - did you find a condition/case with [1]
patches applied, but [2] patches not applied (IOW: current top) where
something isn't being Unref'd properly?

John

> 
> Nikolay
> 
> On 30.10.2017 14:14, John Ferlan wrote:
>> From: Nikolay Shirokovskiy <nshirokovskiy at virtuozzo.com>
>>
>> The problem is incorrect order of qemu driver shutdown and shutdown
>> of netserver threads that serve client requests (thru qemu driver
>> particularly).
>>
>> Net server threads are shutdown upon dispose which is triggered
>> by last daemon object unref at the end of main function. At the same
>> time qemu driver is shutdown earlier in virStateCleanup. As a result
>> netserver threads see invalid driver object in the middle of request
>> processing.
>>
>> Let's move shutting down netserver threads earlier to virNetDaemonClose.
>>
>> Note: order of last daemon unref and virStateCleanup
>> is introduced in 85c3a182 for a valid reason.
>>
>> Signed-off-by: John Ferlan <jferlan at redhat.com>
>> ---
>>  src/rpc/virnetdaemon.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/src/rpc/virnetdaemon.c b/src/rpc/virnetdaemon.c
>> index 8c21414897..33bd8e3b06 100644
>> --- a/src/rpc/virnetdaemon.c
>> +++ b/src/rpc/virnetdaemon.c
>> @@ -881,6 +881,7 @@ virNetDaemonClose(virNetDaemonPtr dmn)
>>      virObjectLock(dmn);
>>  
>>      virHashForEach(dmn->servers, daemonServerClose, NULL);
>> +    virHashRemoveAll(dmn->servers);
>>  
>>      virObjectUnlock(dmn);
>>  }
>>