[PATCH net] net: accept an empty mask in /sys/class/net/*/queues/rx-*/rps_cpus

[Eric Dumazet <edumazet@google.com>]

We must accept an empty mask in store_rps_map(), or we are not able
to disable RPS on a queue.

Fixes: 07bbecb34106 ("net: Restrict receive packets queuing to housekeeping CPUs")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Maciej Żenczykowski <maze@google.com>
Cc: Alex Belits <abelits@marvell.com>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 net/core/net-sysfs.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 9de33b594ff2693c054022a42703c90084122444..efec66fa78b70b2fe5b0a5920317eb1d0415d9e3 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -757,11 +757,13 @@ static ssize_t store_rps_map(struct netdev_rx_queue *queue,
 		return err;
 	}
 
-	hk_flags = HK_FLAG_DOMAIN | HK_FLAG_WQ;
-	cpumask_and(mask, mask, housekeeping_cpumask(hk_flags));
-	if (cpumask_empty(mask)) {
-		free_cpumask_var(mask);
-		return -EINVAL;
+	if (!cpumask_empty(mask)) {
+		hk_flags = HK_FLAG_DOMAIN | HK_FLAG_WQ;
+		cpumask_and(mask, mask, housekeeping_cpumask(hk_flags));
+		if (cpumask_empty(mask)) {
+			free_cpumask_var(mask);
+			return -EINVAL;
+		}
 	}
 
 	map = kzalloc(max_t(unsigned int,
-- 
2.28.0.236.gb10cc79966-goog