[Xen-devel] [PATCH net] xen-netback: respect user provided max_queues

[Wei Liu <wei.liu2@xxxxxxxxxx>]

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>
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
Cc: Johnny Strom <johnny.strom@xxxxxxxxxxxxxxxxx>
Cc: David Vrabel <david.vrabel@xxxxxxxxxx>
---
 drivers/net/xen-netback/netback.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/xen-netback/netback.c 
b/drivers/net/xen-netback/netback.c
index 42569b9..b219a80 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -67,7 +67,7 @@ module_param(rx_drain_timeout_msecs, uint, 0444);
 unsigned int rx_stall_timeout_msecs = 60000;
 module_param(rx_stall_timeout_msecs, uint, 0444);
 
-unsigned int xenvif_max_queues;
+unsigned int xenvif_max_queues = 0;
 module_param_named(max_queues, xenvif_max_queues, uint, 0644);
 MODULE_PARM_DESC(max_queues,
                 "Maximum number of queues per virtual interface");
@@ -2105,8 +2105,11 @@ 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",
-- 
2.1.4


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