Re: [RFC PATCH 3/5] sunrpc: wait for gssproxy to start on initial upcall attempt before falling back to legacy upcall

["J. Bruce Fields" <bfields@fieldses.org>]

On Thu, Jan 02, 2014 at 06:10:55PM -0500, Jeff Layton wrote:
> On Thu, 2 Jan 2014 16:35:47 -0500
> "J. Bruce Fields" <bfields@fieldses.org> wrote:
> 
> > On Wed, Jan 01, 2014 at 07:28:32AM -0500, Jeff Layton wrote:
> > > Currently, the only thing that waits for gssproxy to start is reads
> > > from the use-gss-proxy procfile. That's a little odd, since nothing
> > > but gssproxy itself will likely ever open that file, and all it does
> > > it write to it.
> > > 
> > > It seems like what we really want instead is for svcrpc code to give
> > > gssproxy a little time to start up in the event that some RPCs come
> > > in before it's ready.
> > 
> > Legacy userspace will never write, so this adds an 5-second delay in
> > that case.
> > 
> > I'd rather avoid any arbitrary timeout.
> > 
> > It seems to me all you need is for gss-proxy to ensure that it does the
> > write to use-gss-proxy before it indicates to whoever started it that
> > it's done starting.
> > 
> > Then as long as the init system orders gss-proxy startup before nfsd
> > startup, we're good.
> > 
> > --b.
> > 
> 
> Yep, that 5s delay on the first upcall was the part that was
> questionable...
> 
> Ok, so basically the behavior you want is:
> 
> "If gssproxy is up and running by the time the first RPC comes in then
>  use that. If not, then use the legacy code."
> 
> I'll respin the set with that behavior in mind. I need to do a bit of
> testing with it too, so it may be a week or so before I repost.

Thanks!

On a quick skim, I thought that rendered the later patches mostly
unnecessary, but I may not have been paying close enough attention....

--b.

> 
> > > 
> > > Change it so that the upcall instead waits a little while for gssproxy
> > > to start before giving up. If the wait times out, we go ahead and
> > > disable gssproxy so that later upcalls don't delay.
> > > 
> > > Signed-off-by: Jeff Layton <jlayton@redhat.com>
> > > ---
> > >  net/sunrpc/auth_gss/svcauth_gss.c | 28 ++++++++++------------------
> > >  1 file changed, 10 insertions(+), 18 deletions(-)
> > > 
> > > diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
> > > index 64c025e..921f388 100644
> > > --- a/net/sunrpc/auth_gss/svcauth_gss.c
> > > +++ b/net/sunrpc/auth_gss/svcauth_gss.c
> > > @@ -1265,24 +1265,6 @@ out:
> > >  
> > >  DEFINE_SPINLOCK(use_gssp_lock);
> > >  
> > > -static bool use_gss_proxy(struct net *net)
> > > -{
> > > -	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
> > > -
> > > -	if (sn->use_gss_proxy != -1)
> > > -		return sn->use_gss_proxy;
> > > -	spin_lock(&use_gssp_lock);
> > > -	/*
> > > -	 * If you wanted gss-proxy, you should have said so before
> > > -	 * starting to accept requests:
> > > -	 */
> > > -	sn->use_gss_proxy = 0;
> > > -	spin_unlock(&use_gssp_lock);
> > > -	return 0;
> > > -}
> > > -
> > > -#ifdef CONFIG_PROC_FS
> > > -
> > >  static int set_gss_proxy(struct net *net, int type)
> > >  {
> > >  	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
> > > @@ -1332,6 +1314,16 @@ static int wait_for_gss_proxy(struct net *net)
> > >  	return ret < 0 ? ret : 0;
> > >  }
> > >  
> > > +static bool use_gss_proxy(struct net *net)
> > > +{
> > > +	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
> > > +
> > > +	if (wait_for_gss_proxy(net))
> > > +		return false;
> > > +	return gssp_ready(sn);
> > > +}
> > > +
> > > +#ifdef CONFIG_PROC_FS
> > >  
> > >  static ssize_t write_gssp(struct file *file, const char __user *buf,
> > >  			 size_t count, loff_t *ppos)
> > > -- 
> > > 1.8.4.2
> > > 
> 
> 
> -- 
> Jeff Layton <jlayton@redhat.com>