Date: Thu, 2 Jan 2014 16:35:47 -0500
From: "J. Bruce Fields" <bfields@fieldses.org>
To: Jeff Layton <jlayton@redhat.com>
Cc: linux-nfs@vger.kernel.org, simo@redhat.com, neilb@suse.de
Subject: Re: [RFC PATCH 3/5] sunrpc: wait for gssproxy to start on initial
 upcall attempt before falling back to legacy upcall
Message-ID: <20140102213547.GD28219@fieldses.org>
References: <1388579314-15255-1-git-send-email-jlayton@redhat.com>
 <1388579314-15255-4-git-send-email-jlayton@redhat.com>
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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.

> 
> 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
>