[PATCH 3.16.y-ckt 015/180] xen-netback: respect user provided max_queues

From: Luis Henriques
Date: Wed Feb 03 2016 - 18:59:55 EST


3.16.7-ckt24 -stable review patch. If anyone has any objections, please let me know.

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

From: Wei Liu <wei.liu2@xxxxxxxxxx>

commit 4c82ac3c37363e8c4ded6a5fe1ec5fa756b34df3 upstream.

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@xxxxxxxxxxxxxxxxx>
Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
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 0c1574212162..4a35be8e397c 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -2008,8 +2008,11 @@ 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",