linux-kernel - [PATCH 3.16.y-ckt 016/180] xen-netfront: respect user provided max

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Date:	Wed,  3 Feb 2016 22:30:22 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Wei Liu <wei.liu2@...rix.com>,
	David Vrabel <david.vrabel@...rix.com>,
	"David S . Miller" <davem@...emloft.net>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 016/180] xen-netfront: respect user provided max_queues

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

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

From: Wei Liu <wei.liu2@...rix.com>

commit 32a844056fd43dda647e1c3c6b9983bdfa04d17d 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.

Signed-off-by: Wei Liu <wei.liu2@...rix.com>
Cc: David Vrabel <david.vrabel@...rix.com>
Reviewed-by: David Vrabel <david.vrabel@...rix.com>
Tested-by: David Vrabel <david.vrabel@...rix.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 drivers/net/xen-netfront.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index 9d3bdea182cd..2fb7f5d23608 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -2405,8 +2405,11 @@ static int __init netif_init(void)
 
 	pr_info("Initialising Xen virtual ethernet driver\n");
 
-	/* Allow as many queues as there are CPUs, by default */
-	xennet_max_queues = num_online_cpus();
+	/* Allow as many queues as there are CPUs if user has not
+	 * specified a value.
+	 */
+	if (xennet_max_queues == 0)
+		xennet_max_queues = num_online_cpus();
 
 	return xenbus_register_frontend(&netfront_driver);
 }