On Wed, Sep 24, 2008 at 12:59:42PM -0400, Trond Myklebust wrote: > On Wed, 2008-09-24 at 12:35 -0400, J. Bruce Fields wrote: > > On Thu, Sep 18, 2008 at 02:24:39PM -0500, Benny Halevy wrote: > > > From: Benny Halevy <bhalevy@xxxxxxxxxxx> > > > > > > since commit ff7d9756b501744540be65e172d27ee321d86103 > > > "nfsd: use static memory for callback program and stats" > > > do_probe_callback uses a static callback program > > > (NFS4_CALLBACK) rather than the one set in clp->cl_callback.cb_prog > > > as passed in by the client in setclientid (4.0) > > > or create_session (4.1). > > > > > > This patches allows allocating cb_program (and cb_stats) dynamically > > > and setting a free_rpc_program function pointer to be > > > called when the rpc_clnt structure is destroyed. > > > > So that means we handle two cases: > > > > - free_rpc_program = NULL: We assume the program and stats are > > in static memory (or module memory--which might be a problem > > if we shut down the server and remove the nfsd module in quick > > succession. I assume there's a similar (probably very > > hard-to-hit) bug on the client too, but haven't looked > > carefully.). > > - free_rpc_program != NULL: We assume this rpc_client is the > > last user of the program. > > > > It seems a little ad hoc, but I can't see why it wouldn't solve the > > problem. > > > > I'd want Trond's ack. > > Well the current implementation is certainly broken. Look at what > happens if I clone the rpc_clnt... Hence the comment that "we assume this rpc_client is the last user of the program." I believe that assumption is correct in the case of nfsd callbacks, so Benny's patch is at least not broken--just a little ad-hoc. So the question is whether the above solution, which addresses only this particular case, is sufficient, or whether we'd like something more general, like adding a reference count to the program along with a free_program callback called only on the final put. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
