On Wed, May 19, 2010 at 10:12:51PM +0000, Haiyang Zhang wrote: > > > Actually, we already assign a default callback function, > > chn_cb_negotiate(), > > > when the channels are opened in vmbus module. It's a real function > > and can > > > handle common negotiation messages. > > > > Then why don't you use it here? > > When vmbus is loaded and channel is offered from HyperV host, the default > callback function, chn_cb_negotiate(), is assigned to the function ptr, and > used to do basic responses of negotiation messages. Great, so that works. > After hv_utils modules is loaded the callback function ptr is overridden by > a specialized function in hv_utils module, and handles each feature (shutdown, > timesync, etc.) differently. That's the problem. Provide a "correct" interface to properly change the callback function. Just setting function pointers in a random manner is ripe for all sorts of bad problems, don't you agree? Heck, I don't see any locking happening here which could cause messages to be handled when things are only half-way set up. Also, what's to say your function pointer write is atomic in the first place :) In short, use proper locking for something like this. > > I still think there's a real problem somewhere else in the architecture > > if such a sleep is necessary... > > > > Is the issue that the modprobe of the hv_vmbus can return before the > > bus > > is really all set up and ready to go? If so, just fix that, then you > > will not need any "sleep" calls anywhere, right? > > After vmbus is loaded, the channel offering will come from the host, then > it initializes the channel. The channel offering can happen a little later > after vmbus_init() is done and modprobe returns. So I think we should let > vmbus_init function wait(sleep) until all channel offerings are received before > returning. This will ensure all channels are ready before modprobe returns. That sounds like a good idea. thanks, greg k-h _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
