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| author | Jakub Kicinski <kuba@kernel.org> | 2020-08-26 12:40:06 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-09-12 14:18:55 +0200 |
| commit | ddb279d64b724b197dec829c016b5d386314b970 (patch) | |
| tree | 85e98e25e14f87bfa37e3ef3f8e73a2dda2c05a3 | |
| parent | 09c45065257b5b194e08a1b4749daeebb961675e (diff) | |
| download | linux-stable-ddb279d64b724b197dec829c016b5d386314b970.tar.gz linux-stable-ddb279d64b724b197dec829c016b5d386314b970.tar.bz2 linux-stable-ddb279d64b724b197dec829c016b5d386314b970.zip | |
net: disable netpoll on fresh napis
[ Upstream commit 96e97bc07e90f175a8980a22827faf702ca4cb30 ]
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 56cd7b83a382..cdc1c3a144e1 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6231,12 +6231,13 @@ 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 849380a622ef..cb67d36f3adb 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -161,7 +161,7 @@ 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); |