Hi, I have two kexts: kext A is a USB driver sub-classed from IOService and Kext B sub-classed from IOEthernetController. B "calls" into "A" at various times to perform functions such as delivering outbound frames. I want to "lock" B from entering into A if A has already been entered (via USB callback, timer, etc.) (i.e., its "gate/lock" is busy). Can someone please give me the basics of how I make a given function entry point into A and have it play the "IO Gate" game (i.e., to make sure it's the only one with the lock). Function calls and a pointer to some sample code would be a big help. Thanks, Scott P.S., sorry for the cross-post: I'm not sure which is the best list for this queston. _______________________________________________ darwin-kernel mailing list | darwin-kernel@lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.