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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 13:39:12 +0200 |
| commit | 652a9dc840fb5bf1274a43a92c76372fac7e1b25 (patch) | |
| tree | 72f53f623640edaf5ea5e9ef14eb8159b4bc09ee | |
| parent | b5782c68d954896ca2e783fc8c7d7f4501b1aed3 (diff) | |
| download | linux-stable-652a9dc840fb5bf1274a43a92c76372fac7e1b25.tar.gz linux-stable-652a9dc840fb5bf1274a43a92c76372fac7e1b25.tar.bz2 linux-stable-652a9dc840fb5bf1274a43a92c76372fac7e1b25.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 7ec549e481e3..d101f95a47fb 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5532,12 +5532,13 @@ 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 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 abab3753a9e0..0b247f7cd583 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -179,7 +179,7 @@ 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); |