[PATCH,RFC 06/09] svcrdma: Add support to svc_rdma_send to handle chained WR

[PATCH,RFC 06/09] svcrdma: Add support to svc_rdma_send to handle chained WR

[Tom Tucker]

WR can be submitted as linked lists of WR. Update the svc_rdma_send
routine to handle WR chains. This will be used to submit a WR that
uses an FRMR with another WR that invalidates the FRMR.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>

---
  net/sunrpc/xprtrdma/svc_rdma_transport.c |   29 
+++++++++++++++++++++--------
  1 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c 
b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index a61caa7..1f561c0 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -1252,17 +1252,23 @@ int svc_rdma_fastreg(struct svcxprt_rdma *xprt,

  int svc_rdma_send(struct svcxprt_rdma *xprt, struct ib_send_wr *wr)
  {
-	struct ib_send_wr *bad_wr;
+	struct ib_send_wr *bad_wr, *n_wr;
+	int wr_count;
+	int i;
  	int ret;

  	if (test_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags))
  		return -ENOTCONN;

  	BUG_ON(wr->send_flags != IB_SEND_SIGNALED);
+	wr_count = 1;
+	for (n_wr = wr->next; n_wr; n_wr = n_wr->next)
+		wr_count++;
+
  	/* If the SQ is full, wait until an SQ entry is available */
  	while (1) {
  		spin_lock_bh(&xprt->sc_lock);
-		if (xprt->sc_sq_depth == atomic_read(&xprt->sc_sq_count)) {
+		if (xprt->sc_sq_depth < atomic_read(&xprt->sc_sq_count) + wr_count) {
  			spin_unlock_bh(&xprt->sc_lock);
  			atomic_inc(&rdma_stat_sq_starve);

@@ -1277,19 +1283,26 @@ int svc_rdma_send(struct svcxprt_rdma *xprt, 
struct ib_send_wr *wr)
  				return 0;
  			continue;
  		}
-		/* Bumped used SQ WR count and post */
-		svc_xprt_get(&xprt->sc_xprt);
+		/* Take a transport ref for each WR posted */
+		for (i = 0; i < wr_count; i++)
+			svc_xprt_get(&xprt->sc_xprt);
+
+		/* Bump used SQ WR count and post */
+		atomic_add(wr_count, &xprt->sc_sq_count);
  		ret = ib_post_send(xprt->sc_qp, wr, &bad_wr);
-		if (!ret)
-			atomic_inc(&xprt->sc_sq_count);
-		else {
-			svc_xprt_put(&xprt->sc_xprt);
+		if (ret) {
+			set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
+			atomic_sub(wr_count, &xprt->sc_sq_count);
+			for (i = 0; i < wr_count; i ++)
+				svc_xprt_put(&xprt->sc_xprt);
  			dprintk("svcrdma: failed to post SQ WR rc=%d, "
  			       "sc_sq_count=%d, sc_sq_depth=%d\n",
  			       ret, atomic_read(&xprt->sc_sq_count),
  			       xprt->sc_sq_depth);
  		}
  		spin_unlock_bh(&xprt->sc_lock);
+		if (ret)
+			wake_up(&xprt->sc_send_wait);
  		break;
  	}
  	return ret;