From: AMEET M. PARANJAPE <aparanja@redhat.com>
Date: Mon, 2 Feb 2009 11:05:51 -0500
Subject: [net] ehea: improve behaviour in low mem conditions
Message-id: 20090202160430.31058.11540.sendpatchset@squad5-lp1.lab.bos.redhat.com
O-Subject: [PATCH RHEL5.4 BZ483148] ehea: Improve driver behaviour in low mem conditions
Bugzilla: 483148
RH-Acked-by: David Miller <davem@redhat.com>
RH-Acked-by: Anton Arapov <aarapov@redhat.com>

RHBZ#:
======
https://bugzilla.redhat.com/show_bug.cgi?id=483148

Description:
===========
Re-worked EHEA driver receive queue fill policies to make the driver more
tolerant in low memory conditions.

RHEL Version Found:
================
RHEL 5.3

kABI Status:
============
No symbols were harmed.

Brew:
=====
Built on all platforms.
http://brewweb.devel.redhat.com/brew/taskinfo?taskID=1667788

Upstream Status:
================
http://git.kernel.org/?p=linux/kernel/git/davem/net-next-2.6.git;a=commit;h=e2878806227d223467f84f900ef4c6733ee166df

Test Status:
============
Without this patch a POWER machine will not successfully configure the EHEA
network interface if the amount of memory available is <12MB for each
receive queue.  With this patch the system is able to successfully configure
the network device even in low memory conditions.

This driver has executed the following tests succesfully with the patch:
- ipv4: ping, flood ping, broadcast ping
- ipv6: ping, flood ping, TCP traffic
- flood ping with big pakets
- ftp tests with large files using 4 connections with TSO on/off
- ftp long run using 4 connections with TSO on/off
- netpipe
- netperf
- netperf via IPv6
- netperf using LRO
- netperf/udp
- vlan ping
- multicast basic
- dlpar memory add
- dlpar port add / remove
===============================================================
Ameet Paranjape 978-392-3903 ext 23903
IBM on-site partner

Proposed Patch:
===============

diff --git a/drivers/net/ehea/ehea.h b/drivers/net/ehea/ehea.h
index eda20da..feab775 100644
--- a/drivers/net/ehea/ehea.h
+++ b/drivers/net/ehea/ehea.h
@@ -40,7 +40,7 @@
 #include <asm/io.h>
 
 #define DRV_NAME	"ehea"
-#define DRV_VERSION	"EHEA_0092-00"
+#define DRV_VERSION	"EHEA_0092-01"
 
 /* eHEA capability flags */
 #define DLPAR_PORT_ADD_REM 1
diff --git a/drivers/net/ehea/ehea_main.c b/drivers/net/ehea/ehea_main.c
index cb99ef2..a009c7f 100644
--- a/drivers/net/ehea/ehea_main.c
+++ b/drivers/net/ehea/ehea_main.c
@@ -373,8 +373,6 @@ static void ehea_refill_rq1(struct ehea_port_res *pr, int index, int nr_of_wqes)
 							      EHEA_L_PKT_SIZE);
 			if (!skb_arr_rq1[index]) {
 				pr->rq1_skba.os_skbs = fill_wqes - i;
-				ehea_error("%s: no mem for skb/%d wqes filled",
-					   dev->name, i);
 				break;
 			}
 		}
@@ -390,26 +388,19 @@ static void ehea_refill_rq1(struct ehea_port_res *pr, int index, int nr_of_wqes)
 	ehea_update_rq1a(pr->qp, adder);
 }
 
-static int ehea_init_fill_rq1(struct ehea_port_res *pr, int nr_rq1a)
+static void ehea_init_fill_rq1(struct ehea_port_res *pr, int nr_rq1a)
 {
-	int ret = 0;
 	struct sk_buff **skb_arr_rq1 = pr->rq1_skba.arr;
 	struct net_device *dev = pr->port->netdev;
 	int i;
 
 	for (i = 0; i < pr->rq1_skba.len; i++) {
 		skb_arr_rq1[i] = netdev_alloc_skb(dev, EHEA_L_PKT_SIZE);
-		if (!skb_arr_rq1[i]) {
-			ehea_error("%s: no mem for skb/%d wqes filled",
-				   dev->name, i);
-			ret = -ENOMEM;
-			goto out;
-		}
+		if (!skb_arr_rq1[i])
+			break;
 	}
 	/* Ring doorbell */
 	ehea_update_rq1a(pr->qp, nr_rq1a);
-out:
-	return ret;
 }
 
 static int ehea_refill_rq_def(struct ehea_port_res *pr,
@@ -438,10 +429,12 @@ static int ehea_refill_rq_def(struct ehea_port_res *pr,
 		u64 tmp_addr;
 		struct sk_buff *skb = netdev_alloc_skb(dev, packet_size);
 		if (!skb) {
-			ehea_error("%s: no mem for skb/%d wqes filled",
-				   pr->port->netdev->name, i);
 			q_skba->os_skbs = fill_wqes - i;
-			ret = -ENOMEM;
+			if (q_skba->os_skbs == q_skba->len - 2) {
+				ehea_info("%s: rq%i ran dry - no mem for skb",
+					  pr->port->netdev->name, rq_nr);
+				ret = -ENOMEM;
+			}
 			break;
 		}
 		skb_reserve(skb, NET_IP_ALIGN);
@@ -1212,11 +1205,11 @@ static int ehea_fill_port_res(struct ehea_port_res *pr)
 	int ret;
 	struct ehea_qp_init_attr *init_attr = &pr->qp->init_attr;
 
-	ret = ehea_init_fill_rq1(pr, init_attr->act_nr_rwqes_rq1
-				     - init_attr->act_nr_rwqes_rq2
-				     - init_attr->act_nr_rwqes_rq3 - 1);
+	ehea_init_fill_rq1(pr, init_attr->act_nr_rwqes_rq1
+			       - init_attr->act_nr_rwqes_rq2
+			       - init_attr->act_nr_rwqes_rq3 - 1);
 
-	ret |= ehea_refill_rq2(pr, init_attr->act_nr_rwqes_rq2 - 1);
+	ret = ehea_refill_rq2(pr, init_attr->act_nr_rwqes_rq2 - 1);
 
 	ret |= ehea_refill_rq3(pr, init_attr->act_nr_rwqes_rq3 - 1);