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

On 14.12.2017 15:31, John Ferlan wrote: > > > 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). Sorry, somehow I lost this impornant notice on my read. I thought [1] was more about valueable but unrelated to this patch cleanup. > > 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]. Unfortunately it is not and looks like patch 4 is not pushed too. Anyway it can't help finishing RPC threads in rigth order to hypervisor drivers cleanup.

> >> >> [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? In a sense yes - virStateCleanup is still called before RPC threads are joined which causes crashes. It is not fixed by [1]. Nikolay

> > John > >> >> Nikolay >> >> On 30.10.2017 14:14, John Ferlan wrote: >>> From: Nikolay Shirokovskiy <nshirokovskiy(a)virtuozzo.com&gt; >>> >>> 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(a)redhat.com&gt; >>> --- >>> 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); >>> } >>>