Sequenced rpc pipes

Jelmer Vernooij jelmer at
Mon Oct 31 23:09:08 GMT 2005

On Mon, Oct 31, 2005 at 01:51:01PM -0800, Jeremy Allison wrote about 'Re: Sequenced rpc pipes':
> On Mon, Oct 31, 2005 at 10:55:56PM +0100, Volker Lendecke wrote:
> > When implementing winbind I found that for example LSA is strictly sequenced.
> > If you asynchronously send a second request on ncacn_np when there's still one
> > unreplied request on the fly, you get a NT_STATUS_PIPE_BUSY on the smbtrans
> > command. So I implemented some workaround in winbind around this. After some
> > irc chat I think this is the wrong level, this should be handled at the dcerpc
> > layer. Attached find some prototype that compiles and survives the normal
> > synchronous RPC-LSA test against w2k3. I did not yet test the sequencing, but I
> > would like to ask whether I am on the right track.
> Yes, I noticed that when re-writing the Samba3 rpc code. There's only
> one outstanding request allowed even if the underlying layer could
> be asynchronous - you get "PIPE_BUSY" errors. I think the server in
> Windows is just synchronous on a pipe.
Yes, that's the default. There is a [async] attribute in IDL that can
make a specific call asynchronous (support for >= W2K). More
information is at



Jelmer Vernooij <jelmer at> -
 00:07:19 up 10 days, 13:12,  4 users,  load average: 0.19, 0.20, 0.16
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