diff options
| author |   Jakub Kicinski <kuba@kernel.org> | 2020-08-26 12:40:06 -0700 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2020-08-26 16:16:39 -0700 |
| commit | 96e97bc07e90f175a8980a22827faf702ca4cb30 (patch) | |
| tree | 12b95b421bf2f7c68f77c5615c3857e9ceef0d63 | |
| parent | ipv4: Silence suspicious RCU usage warning (diff) | |
| download | linux-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>
| -rw-r--r-- | net/core/dev.c | 3 | ||||
| -rw-r--r-- | net/core/netpoll.c | 2 |
2 files changed, 3 insertions, 2 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index d42c9ea0c3c0..95ac7568f693 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6612,12 +6612,13 @@ void netif_napi_add(struct net_device *dev, struct napi_struct *napi, netdev_err_once(dev, "%s() called with weight %d\n", __func__, weight); napi->weight = weight; - list_add(&napi->dev_list, &dev->napi_list); napi->dev = dev; #ifdef CONFIG_NETPOLL napi->poll_owner = -1; #endif set_bit(NAPI_STATE_SCHED, &napi->state); + set_bit(NAPI_STATE_NPSVC, &napi->state); + list_add_rcu(&napi->dev_list, &dev->napi_list); napi_hash_add(napi); } EXPORT_SYMBOL(netif_napi_add); 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); |