On Mon, 2008-04-21 at 17:19 -0400, Chuck Lever wrote: > Hi Trond- > > On Apr 19, 2008, at 4:40 PM, Trond Myklebust wrote: > > We want to ensure that req->rq_private_buf.len is updated before > > req->rq_received, so that call_decode() doesn't use an old value for > > req->rq_rcv_buf.len. > > > > In 'call_decode()' itself, instead of using task->tk_status (which > > is set > > using req->rq_received) must use the actual value of > > req->rq_private_buf.len when deciding whether or not the received > > RPC reply > > is too short. > > > > Finally ensure that we set req->rq_rcv_buf.len to zero when retrying a > > request. A typo meant that we were resetting req->rq_private_buf.len > > in > > call_decode(), and then clobbering that value with the old > > rq_rcv_buf.len > > again in xprt_transmit(). > > After staring at this for a while, the interaction between > xprt_complete_rqst and call_decode isn't clear to me. > > I take it there is no guarantee that the xdr_buf fields and > rq_received are completely updated before the task is awoken and > call_decode runs? The call could complete just as the RPC call is being woken up due to a timeout. In any case, we need to ensure that the ordering of the update is correct. We need to know that if a processor sees req->rq_received as being non-zero, then the same processor will see req->rq_private_buf.len as being updated: on something like an alpha processor or a PPC, we need to use explicit read and write barriers to ensure this. -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@xxxxxxxxxx www.netapp.com -- 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
