From 4c41675adc85891f6605bc94aaa1baf7f7dd67e7 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Wed, 10 Oct 2018 13:27:49 +0100
Subject: [PATCH 2/6] iser: fix posting of receive descriptors

RH-Author: Paolo Bonzini <pbonzini@redhat.com>
Message-id: <20181010132749.7381-1-pbonzini@redhat.com>
Patchwork-id: 82566
O-Subject: [RHEL8 libiscsi PATCH 2/6] iser: fix posting of receive descriptors
Bugzilla: 1634541
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
RH-Acked-by: Thomas Huth <thuth@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

The old code is effectively always posting iser_conn->min_posted_rx
descriptors, since it is

   if (outstanding + iser_conn->min_posted_rx <= iser_conn->qp_max_recv_dtos) {
       if(iser_conn->qp_max_recv_dtos - outstanding > iser_conn->min_posted_rx)
           count = iser_conn->min_posted_rx;
       else
           count = iser_conn->qp_max_recv_dtos - outstanding;

which is equivalent to

    if(iser_conn->qp_max_recv_dtos - outstanding >= iser_conn->min_posted_rx)
        if(iser_conn->qp_max_recv_dtos - outstanding > iser_conn->min_posted_rx)
            count = iser_conn->min_posted_rx;
        else
            count = iser_conn->min_posted_rx;

So the "if" is redundant and the "min_posted_rx" is actually behaving more
like a _maximum_ number of posted descriptors in one iser_post_recvm.
Fix it with the (presumably) intended logic and remove a goto along
the way.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit f0fcee72c477dea57f0a50887b7368ba6d4ec33b)
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 lib/iser.c | 24 +++++++++---------------
 1 file changed, 9 insertions(+), 15 deletions(-)

diff --git a/lib/iser.c b/lib/iser.c
index 4b314be..e5c8435 100644
--- a/lib/iser.c
+++ b/lib/iser.c
@@ -1021,7 +1021,7 @@ iser_rcv_completion(struct iser_rx_desc *rx_desc,
 		    struct iser_conn *iser_conn)
 {
 	struct iscsi_in_pdu *in = NULL;
-	int outstanding, count = 0, err;
+	int empty, err;
 	struct iscsi_context *iscsi = iser_conn->cma_id->context;
 
 	in = iscsi_malloc(iscsi, sizeof(*in));
@@ -1089,23 +1089,17 @@ nop_target:
 	 * for the posted rx bufs refcount to become zero handles everything   */
 	iser_conn->post_recv_buf_count--;
 
-	if ((unsigned char *)rx_desc == iser_conn->login_resp_buf)
-		goto receive;
-
-	outstanding = iser_conn->post_recv_buf_count;
-	if (outstanding + iser_conn->min_posted_rx <= iser_conn->qp_max_recv_dtos) {
-		if(iser_conn->qp_max_recv_dtos - outstanding > iser_conn->min_posted_rx)
-			count = iser_conn->min_posted_rx;
-		else
-			count = iser_conn->qp_max_recv_dtos - outstanding;
-		err = iser_post_recvm(iser_conn, count);
-		if (err) {
-			err = -1;
-			goto error;
+	if ((unsigned char *)rx_desc != iser_conn->login_resp_buf) {
+		empty = iser_conn->qp_max_recv_dtos - iser_conn->post_recv_buf_count;
+		if (empty >= iser_conn->min_posted_rx) {
+			err = iser_post_recvm(iser_conn, empty);
+			if (err) {
+				err = -1;
+				goto error;
+			}
 		}
 	}
 
-receive:
 	err = iscsi_process_pdu(iscsi, in);
 
 error:
-- 
1.8.3.1