Verbs providers may perform house-keeping on a send queue during
each signaled send completion. It is necessary therefore for a verbs
consumer (like xprtrdma) to occasionally force a signaled send
completion if it runs unsignaled some of the time.
xprtrdma does not need signaled completions for Send or FastReg Work
Requests. So, it forces a signal about half way through the send
queue by counting the number of Send Queue Entries it consumes. It
currently does this by counting each ib_post_send as one SQE.
Commit c9918ff56dfb ("xprtrdma: Add ro_unmap_sync method for FRWR")
introduced the ability for frwr_op_unmap_sync to post more than one
WR with a single post_send. Thus the underlying assumption of one WR
per ib_post_send is no longer true.
Also, FastReg is currently never signaled. It should be signaled
once in a while to keep the accounting of consumed SQEs accurate.
While we're here, convert the CQCOUNT macros to the currently
preferred kernel coding style, which is inline functions.
Fixes: c9918ff56dfb ("xprtrdma: Add ro_unmap_sync method for FRWR")
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
net/sunrpc/xprtrdma/frwr_ops.c | 13 ++++++++++---
net/sunrpc/xprtrdma/verbs.c | 10 ++--------
net/sunrpc/xprtrdma/xprt_rdma.h | 20 ++++++++++++++++++--
3 files changed, 30 insertions(+), 13 deletions(-)
diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
index 26b26be..adbf52c 100644
--- a/net/sunrpc/xprtrdma/frwr_ops.c
+++ b/net/sunrpc/xprtrdma/frwr_ops.c
@@ -421,7 +421,7 @@
IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE :
IB_ACCESS_REMOTE_READ;
- DECR_CQCOUNT(&r_xprt->rx_ep);
+ rpcrdma_set_signaled(&r_xprt->rx_ep, ®_wr->wr);
rc = ib_post_send(ia->ri_id->qp, ®_wr->wr, &bad_wr);
if (rc)
goto out_senderr;
@@ -486,7 +486,7 @@
struct rpcrdma_ia *ia = &r_xprt->rx_ia;
struct rpcrdma_mw *mw, *tmp;
struct rpcrdma_frmr *f;
- int rc;
+ int count, rc;
dprintk("RPC: %s: req %p\n", __func__, req);
@@ -496,6 +496,7 @@
* a single ib_post_send() call.
*/
f = NULL;
+ count = 0;
invalidate_wrs = pos = prev = NULL;
list_for_each_entry(mw, &req->rl_registered, mw_list) {
if ((rep->rr_wc_flags & IB_WC_WITH_INVALIDATE) &&
@@ -505,6 +506,7 @@
}
pos = __frwr_prepare_linv_wr(mw);
+ count++;
if (!invalidate_wrs)
invalidate_wrs = pos;
@@ -523,7 +525,12 @@
f->fr_invwr.send_flags = IB_SEND_SIGNALED;
f->fr_cqe.done = frwr_wc_localinv_wake;
reinit_completion(&f->fr_linv_done);
- INIT_CQCOUNT(&r_xprt->rx_ep);
+
+ /* Initialize CQ count, since there is always a signaled
+ * WR being posted here. The new cqcount depends on how
+ * many SQEs are about to be consumed.
+ */
+ rpcrdma_init_cqcount(&r_xprt->rx_ep, count);
/* Transport disconnect drains the receive CQ before it
* replaces the QP. The RPC reply handler won't call us
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index ec74289..451f5f2 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -532,7 +532,7 @@ static void rpcrdma_destroy_id(struct rdma_cm_id *id)
ep->rep_cqinit = ep->rep_attr.cap.max_send_wr/2 - 1;
if (ep->rep_cqinit <= 2)
ep->rep_cqinit = 0; /* always signal? */
- INIT_CQCOUNT(ep);
+ rpcrdma_init_cqcount(ep, 0);
init_waitqueue_head(&ep->rep_connect_wait);
INIT_DELAYED_WORK(&ep->rep_connect_worker, rpcrdma_connect_worker);
@@ -1311,13 +1311,7 @@ struct rpcrdma_regbuf *
dprintk("RPC: %s: posting %d s/g entries\n",
__func__, send_wr->num_sge);
- if (DECR_CQCOUNT(ep) > 0)
- send_wr->send_flags = 0;
- else { /* Provider must take a send completion every now and then */
- INIT_CQCOUNT(ep);
- send_wr->send_flags = IB_SEND_SIGNALED;
- }
-
+ rpcrdma_set_signaled(ep, send_wr);
rc = ib_post_send(ia->ri_id->qp, send_wr, &send_wr_fail);
if (rc)
goto out_postsend_err;
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 6e1bba3..f6ae1b2 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -95,8 +95,24 @@ struct rpcrdma_ep {
struct delayed_work rep_connect_worker;
};
-#define INIT_CQCOUNT(ep) atomic_set(&(ep)->rep_cqcount, (ep)->rep_cqinit)
-#define DECR_CQCOUNT(ep) atomic_sub_return(1, &(ep)->rep_cqcount)
+static inline void
+rpcrdma_init_cqcount(struct rpcrdma_ep *ep, int count)
+{
+ atomic_set(&ep->rep_cqcount, ep->rep_cqinit - count);
+}
+
+/* To update send queue accounting, provider must take a
+ * send completion every now and then.
+ */
+static inline void
+rpcrdma_set_signaled(struct rpcrdma_ep *ep, struct ib_send_wr *send_wr)
+{
+ send_wr->send_flags = 0;
+ if (unlikely(atomic_sub_return(1, &ep->rep_cqcount) <= 0)) {
+ rpcrdma_init_cqcount(ep, 0);
+ send_wr->send_flags = IB_SEND_SIGNALED;
+ }
+}
/* Pre-allocate extra Work Requests for handling backward receives
* and sends. This is a fixed value because the Work Queues are
--
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