Pre-allocate extra send and receive Work Requests needed to handle
backchannel receives and sends.
The transport doesn't know how many extra WRs to pre-allocate until
the xprt_setup_backchannel() call, but that's long after the WRs are
allocated during forechannel setup.
So, use a fixed value for now.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Reviewed-by: Sagi Grimberg <sagig@xxxxxxxxxxxx>
Tested-By: Devesh Sharma <devesh.sharma@xxxxxxxxxxxxx>
---
net/sunrpc/xprtrdma/backchannel.c | 4 ++++
net/sunrpc/xprtrdma/verbs.c | 14 ++++++++++++--
net/sunrpc/xprtrdma/xprt_rdma.h | 10 ++++++++++
3 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/net/sunrpc/xprtrdma/backchannel.c b/net/sunrpc/xprtrdma/backchannel.c
index 3d01b32..3165ed6 100644
--- a/net/sunrpc/xprtrdma/backchannel.c
+++ b/net/sunrpc/xprtrdma/backchannel.c
@@ -125,6 +125,9 @@ int xprt_rdma_bc_setup(struct rpc_xprt *xprt, unsigned int reqs)
* Twice as many rpc_rqsts are prepared to ensure there is
* always an rpc_rqst available as soon as a reply is sent.
*/
+ if (reqs > RPCRDMA_BACKWARD_WRS >> 1)
+ goto out_err;
+
for (i = 0; i < (reqs << 1); i++) {
rqst = kzalloc(sizeof(*rqst), GFP_KERNEL);
if (!rqst) {
@@ -161,6 +164,7 @@ int xprt_rdma_bc_setup(struct rpc_xprt *xprt, unsigned int reqs)
out_free:
xprt_rdma_bc_destroy(xprt, reqs);
+out_err:
pr_err("RPC: %s: setup backchannel transport failed\n", __func__);
return -ENOMEM;
}
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index d920367..d031856 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -570,6 +570,7 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
struct ib_device_attr *devattr = &ia->ri_devattr;
struct ib_cq *sendcq, *recvcq;
struct ib_cq_init_attr cq_attr = {};
+ unsigned int max_qp_wr;
int rc, err;
if (devattr->max_sge < RPCRDMA_MAX_IOVS) {
@@ -578,18 +579,27 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
return -ENOMEM;
}
+ if (devattr->max_qp_wr <= RPCRDMA_BACKWARD_WRS) {
+ dprintk("RPC: %s: insufficient wqe's available\n",
+ __func__);
+ return -ENOMEM;
+ }
+ max_qp_wr = devattr->max_qp_wr - RPCRDMA_BACKWARD_WRS;
+
/* check provider's send/recv wr limits */
- if (cdata->max_requests > devattr->max_qp_wr)
- cdata->max_requests = devattr->max_qp_wr;
+ if (cdata->max_requests > max_qp_wr)
+ cdata->max_requests = max_qp_wr;
ep->rep_attr.event_handler = rpcrdma_qp_async_error_upcall;
ep->rep_attr.qp_context = ep;
ep->rep_attr.srq = NULL;
ep->rep_attr.cap.max_send_wr = cdata->max_requests;
+ ep->rep_attr.cap.max_send_wr += RPCRDMA_BACKWARD_WRS;
rc = ia->ri_ops->ro_open(ia, ep, cdata);
if (rc)
return rc;
ep->rep_attr.cap.max_recv_wr = cdata->max_requests;
+ ep->rep_attr.cap.max_recv_wr += RPCRDMA_BACKWARD_WRS;
ep->rep_attr.cap.max_send_sge = RPCRDMA_MAX_IOVS;
ep->rep_attr.cap.max_recv_sge = 1;
ep->rep_attr.cap.max_inline_data = 0;
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 1eb86c79f..55d2660 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -101,6 +101,16 @@ struct rpcrdma_ep {
*/
#define RPCRDMA_IGNORE_COMPLETION (0ULL)
+/* Pre-allocate extra Work Requests for handling backward receives
+ * and sends. This is a fixed value because the Work Queues are
+ * allocated when the forward channel is set up.
+ */
+#if defined(CONFIG_SUNRPC_BACKCHANNEL)
+#define RPCRDMA_BACKWARD_WRS (8)
+#else
+#define RPCRDMA_BACKWARD_WRS (0)
+#endif
+
/* Registered buffer -- registered kmalloc'd memory for RDMA SEND/RECV
*
* The below structure appears at the front of a large region of kmalloc'd
--
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