From: Michael Kelley mhklinux@outlook.com Sent: Tuesday, October 29, 2024 4:45 PM [...] An alternate approach occurs to me. util_probe() does these three things in order:
- Allocates the receive buffer
- Calls the util_init() function, which for KVP and VSS creates the char dev
- Sets up the VMBus channel, including calling vmbus_open()
What if the order of #2 and #3 were swapped in util_probe()? I don't immediately see any interdependency between #2 and #3 for KVP and VSS, nor for Shutdown and Timesync. With the swap, the VMBus channel would be fully open by the time the /dev entry appears and the user space daemon can do anything.
I haven't though too deeply about this, so maybe there's a problem somewhere. But if not, it seems a lot cleaner.
Michael
I think #3 depends on #2, e.g. hv_kvp_init() sets the channel's preferred max_pkt_size, which is tested later in __vmbus_open().
Another example of dependency is: hv_timesync_init() initializes host_ts.lock and adj_time_work, which are used by timesync_onchannelcallback() -> adj_guesttime(). Note: the channel callback can be already running before vmbus_open() returns.
Thanks, Dexuan