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RPC/RDMA: fix connection IRD/ORD setting

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This logic sets the connection parameter that configures the local device
and informs the remote peer how many concurrent incoming RDMA_READ
requests are supported. The original logic didn't really do what was
intended for two reasons:

- The max number supported by the device is typically smaller than
any one factor in the calculation used, and

- The field in the connection parameter structure where the value is
stored is a u8 and always overflows for the default settings.

So what really happens is the value requested for responder resources
is the left over 8 bits from the "desired value". If the desired value
happened to be a multiple of 256, the result was zero and it wouldn't
connect at all.

Given the above and the fact that max_requests is almost always larger
than the max responder resources supported by the adapter, this patch
simplifies this logic and simply requests the max supported by the device,
subject to a reasonable limit.

This bug was found by Jim Schutt at Sandia.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Acked-by: Tom Talpey <talpey@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Tom Tucker 2008-10-09 15:00:30 -04:00 committed by Trond Myklebust
parent 3197d309f5
commit b334eaabf4
1 changed files with 15 additions and 38 deletions
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53
net/sunrpc/xprtrdma/verbs.c
View File

@ -705,30 +705,13 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
ep->rep_remote_cma.private_data_len = 0;
/* Client offers RDMA Read but does not initiate */
switch (ia->ri_memreg_strategy) {
case RPCRDMA_BOUNCEBUFFERS:
ep->rep_remote_cma.responder_resources = 0;
break;
case RPCRDMA_MTHCAFMR:
case RPCRDMA_REGISTER:
case RPCRDMA_FRMR:
ep->rep_remote_cma.responder_resources = cdata->max_requests *
(RPCRDMA_MAX_DATA_SEGS / 8);
break;
case RPCRDMA_MEMWINDOWS:
case RPCRDMA_MEMWINDOWS_ASYNC:
#if RPCRDMA_PERSISTENT_REGISTRATION
case RPCRDMA_ALLPHYSICAL:
#endif
ep->rep_remote_cma.responder_resources = cdata->max_requests *
(RPCRDMA_MAX_DATA_SEGS / 2);
break;
default:
break;
}
if (ep->rep_remote_cma.responder_resources > devattr.max_qp_rd_atom)
ep->rep_remote_cma.responder_resources = devattr.max_qp_rd_atom;
ep->rep_remote_cma.initiator_depth = 0;
if (ia->ri_memreg_strategy == RPCRDMA_BOUNCEBUFFERS)
ep->rep_remote_cma.responder_resources = 0;
else if (devattr.max_qp_rd_atom > 32) /* arbitrary but <= 255 */
ep->rep_remote_cma.responder_resources = 32;
else
ep->rep_remote_cma.responder_resources = devattr.max_qp_rd_atom;
ep->rep_remote_cma.retry_count = 7;
ep->rep_remote_cma.flow_control = 0;
@ -858,14 +841,6 @@ if (strnicmp(ia->ri_id->device->dma_device->bus->name, "pci", 3) == 0) {
}
}
/* Theoretically a client initiator_depth > 0 is not needed,
* but many peers fail to complete the connection unless they
* == responder_resources! */
if (ep->rep_remote_cma.initiator_depth !=
ep->rep_remote_cma.responder_resources)
ep->rep_remote_cma.initiator_depth =
ep->rep_remote_cma.responder_resources;
ep->rep_connected = 0;
rc = rdma_connect(ia->ri_id, &ep->rep_remote_cma);
@ -894,14 +869,16 @@ if (strnicmp(ia->ri_id->device->dma_device->bus->name, "pci", 3) == 0) {
if (ep->rep_connected <= 0) {
/* Sometimes, the only way to reliably connect to remote
* CMs is to use same nonzero values for ORD and IRD. */
ep->rep_remote_cma.initiator_depth =
ep->rep_remote_cma.responder_resources;
if (ep->rep_remote_cma.initiator_depth == 0)
++ep->rep_remote_cma.initiator_depth;
if (ep->rep_remote_cma.responder_resources == 0)
++ep->rep_remote_cma.responder_resources;
if (retry_count++ == 0)
if (retry_count++ <= RDMA_CONNECT_RETRY_MAX + 1 &&
(ep->rep_remote_cma.responder_resources == 0 ||
ep->rep_remote_cma.initiator_depth !=
ep->rep_remote_cma.responder_resources)) {
if (ep->rep_remote_cma.responder_resources == 0)
ep->rep_remote_cma.responder_resources = 1;
ep->rep_remote_cma.initiator_depth =
ep->rep_remote_cma.responder_resources;
goto retry;
}
rc = ep->rep_connected;
} else {
dprintk("RPC: %s: connected\n", __func__);