[3.19.y-ckt stable] Patch "xen-netback: respect user provided max_queues" has been added to the 3.19.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    xen-netback: respect user provided max_queues

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt14.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From bfc924ece6e51d18bc7b31aecc6a7c6f9a5c2f5d Mon Sep 17 00:00:00 2001
From: Wei Liu <wei.liu2 at citrix.com>
Date: Thu, 10 Sep 2015 11:18:57 +0100
Subject: xen-netback: respect user provided max_queues

[ Upstream commit 4c82ac3c37363e8c4ded6a5fe1ec5fa756b34df3 ]

Originally that parameter was always reset to num_online_cpus during
module initialisation, which renders it useless.

The fix is to only set max_queues to num_online_cpus when user has not
provided a value.

Reported-by: Johnny Strom <johnny.strom at linuxsolutions.fi>
Signed-off-by: Wei Liu <wei.liu2 at citrix.com>
Reviewed-by: David Vrabel <david.vrabel at citrix.com>
Acked-by: Ian Campbell <ian.campbell at citrix.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/net/xen-netback/netback.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 83f7da7..9a6dfb5 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -2178,8 +2178,11 @@ static int __init netback_init(void)
 	if (!xen_domain())
 		return -ENODEV;

-	/* Allow as many queues as there are CPUs, by default */
-	xenvif_max_queues = num_online_cpus();
+	/* Allow as many queues as there are CPUs if user has not
+	 * specified a value.
+	 */
+	if (xenvif_max_queues == 0)
+		xenvif_max_queues = num_online_cpus();

 	if (fatal_skb_slots < XEN_NETBK_LEGACY_SLOTS_MAX) {
 		pr_info("fatal_skb_slots too small (%d), bump it to XEN_NETBK_LEGACY_SLOTS_MAX (%d)\n",
--
1.9.1