svcrdma: Fix SQ wake-ups

Ensure there is a wake-up when increasing sc_sq_avail.

Likewise, if a wake-up is done, sc_sq_avail needs to be updated,
otherwise the wait_event() conditional is never going to be met.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

net/sunrpc/xprtrdma/svc_rdma_sendto.c

@@ -335,11 +335,11 @@ int svc_rdma_send(struct svcxprt_rdma *rdma, struct svc_rdma_send_ctxt *ctxt)
 	/* If the SQ is full, wait until an SQ entry is available */
 	while (1) {
 		if ((atomic_dec_return(&rdma->sc_sq_avail) < 0)) {
+			svc_rdma_wake_send_waiters(rdma, 1);
 			percpu_counter_inc(&svcrdma_stat_sq_starve);
 			trace_svcrdma_sq_full(rdma, &ctxt->sc_cid);
-			atomic_inc(&rdma->sc_sq_avail);
 			wait_event(rdma->sc_send_wait,
-				   atomic_read(&rdma->sc_sq_avail) > 1);
+				   atomic_read(&rdma->sc_sq_avail) > 0);
 			if (test_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags))
 				return -ENOTCONN;
 			trace_svcrdma_sq_retry(rdma, &ctxt->sc_cid);
@@ -355,7 +355,7 @@ int svc_rdma_send(struct svcxprt_rdma *rdma, struct svc_rdma_send_ctxt *ctxt)
 
 	trace_svcrdma_sq_post_err(rdma, &ctxt->sc_cid, ret);
 	svc_xprt_deferred_close(&rdma->sc_xprt);
-	wake_up(&rdma->sc_send_wait);
+	svc_rdma_wake_send_waiters(rdma, 1);
 	return ret;
 }