On 05/09/2017 11:51 AM, Timur Tabi wrote: > On 05/09/2017 01:46 PM, Florian Fainelli wrote: >> A good test case for exercising a .shutdown() function is kexec'ing a >> new kernel for instance. > > I tried that. I run iperf in one window while launching kexec in another. > Even without a shutdown function, network traffic appear to halt on its own > and the kexec succeeds. > > Is it possible that the network stack detects a kexec and automatically > stops all network devices?
No. why would it? However the device driver model does call into your driver's remove function and that one does a right job already because it does an network device unregister, and so on. There is no strict requirement for implementing a .shutdown() function AFAICT and it does not necessarily make sense to have one depending on the bus type. For platform/MMIO devices, it hardly has any value, but on e.g: PCI, it could be added as an additional step to perform a full device shutdown. > >> You should put your HW in a state where it won't be doing DMA, or have >> any adverse side effects to the system, putting it in a low power state >> is also a good approach. > > My in-house driver stops the RX and TX queues. I'm guessing that's good > enough, but I don't have a failing test case to prove it. > That's probably good enough, yes. -- Florian
