net: sched: flower: handle concurrent filter insertion in fl_change
Check if user specified a handle and another filter with the same handle
was inserted concurrently. Return EAGAIN to retry filter processing (in
case it is an overwrite request).
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index db47828..70b357f 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -1542,6 +1542,15 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
/* user specifies a handle and it doesn't exist */
err = idr_alloc_u32(&head->handle_idr, fnew, &handle,
handle, GFP_ATOMIC);
+
+ /* Filter with specified handle was concurrently
+ * inserted after initial check in cls_api. This is not
+ * necessarily an error if NLM_F_EXCL is not set in
+ * message flags. Returning EAGAIN will cause cls_api to
+ * try to update concurrently inserted rule.
+ */
+ if (err == -ENOSPC)
+ err = -EAGAIN;
} else {
handle = 1;
err = idr_alloc_u32(&head->handle_idr, fnew, &handle,