From: Jakub Kicinski <jakub.kicin...@netronome.com> Date: Mon, 12 Feb 2018 21:35:31 -0800
> netif_set_real_num_tx_queues() can be called when netdev is up. > That usually happens when user requests change of number of > channels/rings with ethtool -L. The procedure for changing > the number of queues involves resetting the qdiscs and setting > dev->num_tx_queues to the new value. When the new value is > lower than the old one, extra care has to be taken to ensure > ordering of accesses to the number of queues vs qdisc reset. > > Currently the queues are reset before new dev->num_tx_queues > is assigned, leaving a window of time where packets can be > enqueued onto the queues going down, leading to a likely > crash in the drivers, since most drivers don't check if TX > skbs are assigned to an active queue. > > Fixes: e6484930d7c7 ("net: allocate tx queues in register_netdevice") > Signed-off-by: Jakub Kicinski <jakub.kicin...@netronome.com> > --- > Also reported: http://lists.openwall.net/netdev/2017/04/26/211, > GSO just made it more likely. Looks good, applied and queued up for -stable, thanks!