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authorJakub Kicinski <kuba@kernel.org>2020-08-26 12:40:06 -0700
committerDavid S. Miller <davem@davemloft.net>2020-08-26 16:16:39 -0700
commit96e97bc07e90f175a8980a22827faf702ca4cb30 (patch)
tree12b95b421bf2f7c68f77c5615c3857e9ceef0d63 /net/core/netpoll.c
parentipv4: Silence suspicious RCU usage warning (diff)
downloadlinux-dev-96e97bc07e90f175a8980a22827faf702ca4cb30.tar.xz
linux-dev-96e97bc07e90f175a8980a22827faf702ca4cb30.zip
net: disable netpoll on fresh napis
napi_disable() makes sure to set the NAPI_STATE_NPSVC bit to prevent netpoll from accessing rings before init is complete. However, the same is not done for fresh napi instances in netif_napi_add(), even though we expect NAPI instances to be added as disabled. This causes crashes during driver reconfiguration (enabling XDP, changing the channel count) - if there is any printk() after netif_napi_add() but before napi_enable(). To ensure memory ordering is correct we need to use RCU accessors. Reported-by: Rob Sherwood <rsher@fb.com> Fixes: 2d8bff12699a ("netpoll: Close race condition between poll_one_napi and napi_disable") Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/netpoll.c')
-rw-r--r--net/core/netpoll.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 093e90e52bc2..2338753e936b 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -162,7 +162,7 @@ static void poll_napi(struct net_device *dev)
struct napi_struct *napi;
int cpu = smp_processor_id();
- list_for_each_entry(napi, &dev->napi_list, dev_list) {
+ list_for_each_entry_rcu(napi, &dev->napi_list, dev_list) {
if (cmpxchg(&napi->poll_owner, -1, cpu) == -1) {
poll_one_napi(napi);
smp_store_release(&napi->poll_owner, -1);