Change Details

When a ng_tty node receives a byte or packet from the device, it sends the data up through its hook. Once it makes its way up to an ng_iface node, it gets dispatched through netisr, so the thread must have a VNET context set. By default ng_tty will use direct dispatch, i.e., the thread calling the TTY hook will pass packets all the way up to netisr. However, it does not set a VNET context, so in this case we crash. Work around the problem by queueing all packets through netgraph worker threads, which do set the vnet context appropriately. This is obviously not an optimal solution, but I am not sure how we can derive the correct vnet in TTY. If someone more familiar with netgraph than me can suggest something, I'd appreciate it. In the meantime, this diff ensures that ng_tty is not totally broken when VIMAGE is enabled.

When a ng_tty node receives a byte or packet from the device, it sends the data up through its hook. Once it makes its way up to an ng_iface node, it gets dispatched through netisr, so the thread must have a VNET context set. By default ng_tty will use direct dispatch, i.e., the thread calling the TTY hook will pass packets all the way up to netisr. However, it does not set a VNET context, so in this case we crash. Work around the problem by queueing all packets through netgraph worker threads, which do set the vnet context appropriately. This is obviously not an optimal solution, but I am not sure how we can derive the correct vnet in ng_tty. If someone more familiar with netgraph than me can suggest something, I'd appreciate it. In the meantime, this diff ensures that ng_tty is not totally broken when VIMAGE is enabled.

When a ng_tty node receives a byte or packet from the device, it sends the data up through its hook. Once it makes its way up to an ng_iface node, it gets dispatched through netisr, so the thread must have a VNET context set. By default ng_tty will use direct dispatch, i.e., the thread calling the TTY hook will pass packets all the way up to netisr. However, it does not set a VNET context, so in this case we crash. Work around the problem by queueing all packets through netgraph worker threads, which do set the vnet context appropriately. This is obviously not an optimal solution, but I am not sure how we can derive the correct vnet in TTYng_tty. If someone more familiar with netgraph than me can suggest something, I'd appreciate it. In the meantime, this diff ensures that ng_tty is not totally broken when VIMAGE is enabled.