diff options
| author | Jakub Kicinski <kuba@kernel.org> | 2020-08-26 12:40:06 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-09-12 11:45:33 +0200 |
| commit | 3fe69cc4436810cbbf07b1191af05bd3ca18837d (patch) | |
| tree | 911e89f7e12808b88c7a985f0ed037547a271605 | |
| parent | 32a8e4e2d10dee4030629e7c528f1d36f0004d16 (diff) | |
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 09115c68f29d..59157e9686fb 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4849,13 +4849,14 @@ void netif_napi_add(struct net_device *dev, struct napi_struct *napi, pr_err_once("netif_napi_add() called with weight %d on device %s\n", weight, dev->name); napi->weight = weight; - list_add(&napi->dev_list, &dev->napi_list); napi->dev = dev; #ifdef CONFIG_NETPOLL spin_lock_init(&napi->poll_lock); 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); } EXPORT_SYMBOL(netif_napi_add); diff --git a/net/core/netpoll.c b/net/core/netpoll.c index 0d7c2cc1ff09..f2610f8f171c 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -178,7 +178,7 @@ static void poll_napi(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() && spin_trylock(&napi->poll_lock)) { poll_one_napi(napi); |