[libvirt] [PATCH 1/3] Debug: Add WARN'ing messages for when a client has opened/closed connection.

[Prerna]

I looked through what you were suggesting.
I was assuming virNetSocketGetFD()would do a NULL check for the sock arg,
and would return immediately if a different client executed a
virNetServerClientClose() setting client->sock to null.

Since this check is missing, I understand the implicit assumption is to
always have virNetServerClientGetFD() lock the client, and consequently, I
will rearrange debug messages around to prevent lock contention.

Sending out a V2.

On Wed, Mar 22, 2017 at 1:41 PM, Peter Krempa <pkrempa at redhat.com> wrote:

> On Wed, Mar 22, 2017 at 01:02:17 -0700, Prerna Saxena wrote:
> > While tracing connections from a remote client, it helps to keep track
> > of the connection lifecycle. Messages such as the following :
> >
> > error : virNetSocketReadWire:1574 : End of file while reading data:
> Input/output error
> >
> > are rather unhelpful. They do not indicate if the client had earlier
> asked for
> > connection closure via libvirt API.
> > This patch introduces messages to annotate when a client
> connected/disconnected.
> >
> > Signed-off-by: Prerna Saxena <saxenap.ltc at gmail.com>
> > ---
> >  src/rpc/virnetserverclient.c | 18 ++++++++++++++----
> >  1 file changed, 14 insertions(+), 4 deletions(-)
> >
> > diff --git a/src/rpc/virnetserverclient.c b/src/rpc/virnetserverclient.c
> > index 85857bc..a77feaa 100644
> > --- a/src/rpc/virnetserverclient.c
> > +++ b/src/rpc/virnetserverclient.c
> > @@ -678,14 +678,19 @@ int virNetServerClientGetTLSKeySize(virNetServerClientPtr
> client)
> >      return size;
> >  }
> >  #endif
> > -
> > +/*
> > + * This mostly just needs to publish the client socket FD to logs.
> > + * It does not necessarily need a lock, or will add lock contention
> problems.
> > + * Replace the lock with a reference counting mechanism, to prevent the
> client
> > + * object from being deallocated while this is being run
> > + */
> >  int virNetServerClientGetFD(virNetServerClientPtr client)
> >  {
> >      int fd = -1;
> > -    virObjectLock(client);
> > +    virObjectRef(client);
> >      if (client->sock)
> >          fd = virNetSocketGetFD(client->sock);
> > -    virObjectUnlock(client);
> > +    virObjectUnref(client);
>
> This change is not justified in any way. Also looks wrong. You can't
> access an unlocked object.
>
> >      return fd;
> >  }
> >
> > @@ -965,7 +970,9 @@ void virNetServerClientClose(virNetServerClientPtr
> client)
> >      virKeepAlivePtr ka;
> >
> >      virObjectLock(client);
> > -    VIR_DEBUG("client=%p", client);
> > +    VIR_WARN("Free'ing up resources for client=%p sock=%d", client,
> > +               virNetServerClientGetFD(client));
>
> NACK using warnings instead of debug messages is not desired. For debug
> purposes you should use debug logs.
>
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