From 9a2d93899897efb0702f97e71387f9d0ae94a9d5 Mon Sep 17 00:00:00 2001 From: Vlad Buslov Date: Thu, 21 Mar 2019 15:17:40 +0200 Subject: [PATCH] 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 Acked-by: Jiri Pirko Reviewed-by: Stefano Brivio Signed-off-by: David S. Miller --- net/sched/cls_flower.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c index db47828ea5e2..70b357f23391 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,