netdev - [RFC -next 3/3] net: make sure napi_list is safe for RCU traversal

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Message-Id: <20200827223250.2045503-4-kuba@kernel.org>
Date:   Thu, 27 Aug 2020 15:32:50 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     eric.dumazet@...il.com
Cc:     davem@...emloft.net, netdev@...r.kernel.org, kernel-team@...com,
        Jakub Kicinski <kuba@...nel.org>
Subject: [RFC -next 3/3] net: make sure napi_list is safe for RCU traversal

netpoll needs to traverse dev->napi_list under RCU, make
sure it uses the right iterator and that removal from this
list is handled safely.

Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
 net/core/dev.c     | 2 +-
 net/core/netpoll.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 623060907132..dfb4a4137eea 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6656,7 +6656,7 @@ void __netif_napi_del(struct napi_struct *napi)
 		return;
 
 	napi_hash_del(napi);
-	list_del_init(&napi->dev_list);
+	list_del_rcu(&napi->dev_list);
 	napi_free_frags(napi);
 
 	flush_gro_hash(napi);
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 2338753e936b..c310c7c1cef7 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -297,7 +297,7 @@ static int netpoll_owner_active(struct net_device *dev)
 {
 	struct napi_struct *napi;
 
-	list_for_each_entry(napi, &dev->napi_list, dev_list) {
+	list_for_each_entry_rcu(napi, &dev->napi_list, dev_list) {
 		if (napi->poll_owner == smp_processor_id())
 			return 1;
 	}
-- 
2.26.2