From: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Date: Wed, 7 Mar 2018 13:19:43 +0000 (+0100)
Subject: s390/qdio: restrict buffer merging to eligible devices
X-Git-Tag: v4.17-rc1~78^2~14
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=c11a3dfd6fedd5266c2f9d7286981dc804dfb7cc;p=linux.git

s390/qdio: restrict buffer merging to eligible devices

Only attempt to merge PENDING into EMPTY buffers for devices where
the PENDING state is actually expected (ie. IQD with CQ).
This might speed up the hot path a little bit.

Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Reviewed-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---

diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
index bd26df85f559..63c6e9cf958f 100644
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -761,7 +761,8 @@ static int get_outbound_buffer_frontier(struct qdio_q *q)
 	if (!count)
 		goto out;
 
-	count = get_buf_states(q, q->first_to_check, &state, count, 0, 1);
+	count = get_buf_states(q, q->first_to_check, &state, count, 0,
+			       q->u.out.use_cq);
 	if (!count)
 		goto out;