[libvirt] [PATCH v2 16/24] network_conf: Introduce locked versions of lookup functions

Peter Krempa pkrempa at redhat.com
Fri Mar 6 08:15:05 UTC 2015


On Thu, Mar 05, 2015 at 16:58:08 +0100, Peter Krempa wrote:
> On Thu, Mar 05, 2015 at 12:05:17 +0100, Michal Privoznik wrote:
> > This is going to be needed later, when some functions needs to avoid
> > calling multiple times at once. It will work like this:
> > 
> > 1) gain the object list mutex
> > 2) find the object to work on
> > 3) do the work
> > 4) release the mutex
> > 
> > As an example of such function is virNetworkAssignDef(). The other
> > use case might be in virNetworkObjListForEach() callback.
> > 
> > Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> > ---
> >  src/conf/network_conf.c  | 45 ++++++++++++++++++++++++++++++++++-----------
> >  src/conf/network_conf.h  |  4 ++++
> >  src/libvirt_private.syms |  2 ++
> >  3 files changed, 40 insertions(+), 11 deletions(-)
> > 
> > diff --git a/src/conf/network_conf.c b/src/conf/network_conf.c
> > index a821f6c..8cf9ffd 100644
> > --- a/src/conf/network_conf.c
> > +++ b/src/conf/network_conf.c
> > @@ -153,34 +153,57 @@ virNetworkObjListPtr virNetworkObjListNew(void)
> >      return nets;
> >  }
> >  
> > +virNetworkObjPtr
> > +virNetworkObjFindByUUIDLocked(virNetworkObjListPtr nets,
> > +                              const unsigned char *uuid)
> > +{
> > +    size_t i;
> > +
> > +    for (i = 0; i < nets->count; i++) {
> > +        virObjectLock(nets->objs[i]);
> > +        if (!memcmp(nets->objs[i]->def->uuid, uuid, VIR_UUID_BUFLEN))
> > +            return nets->objs[i];
> 
> This also creates a deadlock that you fix in the next one. Looks like a
> rebase artifact.

Disregard this please, the locking is right, just the changes in the
next patch confused me at first.

Peter
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