On 05/26/2010 11:25 PM, Haiyang Zhang wrote: >> From: Greg KH [mailto:gregkh@xxxxxxx] >>> + VmbusChannelOpen(newChannel, 2 * PAGE_SIZE, >>> + 2 * PAGE_SIZE, NULL, 0, >>> + hv_cb_utils[cnt].callback, >>> + newChannel) == 0) { >>> + hv_cb_utils[cnt].channel = newChannel; >>> + mb(); >> >> What is the mb() call for? Why is it necessary? (hint, if you need it, >> something else is really wrong...) > > It ensures the channel assignment happens before the wakeup call: > osd_WaitEventSet(ic_channel_ready), if the compiler optimization re-arrange > the execution order. wake_up() is a barrier, you don't need the mb() there. BTW osd_WaitEventSet et al. can be easily converted to completion. -- js _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
