On Tuesday, April 26, 2011 10:42:17 am Hans Petter Selasky wrote: > On Tuesday 26 April 2011 16:37:17 John Baldwin wrote: > > On Tuesday, April 26, 2011 10:27:14 am Warner Losh wrote: > > > On Apr 26, 2011, at 7:42 AM, John Baldwin wrote: > > > > - The Giant protection for new-bus should prevent attach/detach from > > > > running > > > > > > > > concurrently I believe (either that or the USB bus itself should > > > > ensure that the two instances of your device have seperate device_t > > > > instances with separate softc's, so current attach/detach should not > > > > matter except that they may both try to talk to the same hardware > > > > perhaps? In that case that is something the USB bus driver should > > > > fix by prevent a device from attaching at an existing address until > > > > any existing device at that address is fully detached). > > > > > > I thought that if we held Giant when we're about to go to sleep that we > > > drop it as a special case. So if any newbus-releated function sleeps, > > > we can have a situation where attach is running and detach gets called. > > > There is (or was) some code to cope with this in CardBus, iirc. I'm > > > surprised there isn't any in USB, since Hans was the one that alerted me > > > to this issue. > > > > Yes, Giant doesn't really provide too much help here. However, the real > > fix should be in the USB bus, and USB peripheral drivers should not have > > to worry about handling concurrent attach/detach (they can't really handle > > it safely anyway). > > Hi, > > All detach/attach/suspend/resume functions on a device tree belonging to the > same USB controller are executed from a single thread, which is called the > root HUB thread.
Ok, that should work fine then to serialize the detach and attach. -- John Baldwin _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
