On Wed, May 26, 2010 at 09:25:31PM +0000, Haiyang Zhang wrote: > > From: Greg KH [mailto:gregkh@xxxxxxx] > > > + static atomic_t ic_channel_initcnt = ATOMIC_INIT(0); > > Why is this an atomic_t? > > As discussed previously, I used atomic_t to handle more general case > if vmbus interrupts happen on every cpu. Ok, but then you should use a lock to protect the variable, not an atomic_t. > > > > + 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. If you care about this, because some other thread is looking at it, then you really need to protect it with a lock. Don't rely on a mb() to get it all correct for you (hint, I doubt it will...) > > Something wierd happened with your indentation here, it doesn't line up > > properly. That call to VmbusChannelOpen() needs to go in a full tab, > > not 4 spaces. > > > > Please always run your patch through the checkpatch.pl script before > > sending it to me. > > Sure, I will replace it with TAB. I already ran checkpatch.pl on > this patch -- no error: > staging-next-2.6> scripts/checkpatch.pl 0525-Fix-race-condition-on-IC-channel-initialization.patch > total: 0 errors, 0 warnings, 71 lines checked > > 0525-Fix-race-condition-on-IC-channel-initialization.patch has no obvious style problems and is ready for submission. Looks like a bug in checkpatch.pl, go poke Andy about that please. > > > +struct osd_waitevent *ic_channel_ready; > > > > What's with the "ic_" naming scheme here? It should be "hv_" right? > > IC stands for "integration components", such as Shutdown, Timesync, > Heartbeat, etc. Yes, I know what it stands for, but the rest of the world doesn't :) > > As you are using this "ic_channel_ready variable only within the > > vmbus_bus_init() call, why not just make it local to there? Then > > there's no need to do the create/init/wait/free sequence outside the > > init call. > > > > The init call should just do all of this for us, right? > > The ic_channel_ready variable is called by VmbusChannelProcessOffer / > osd_WaitEventSet(ic_channel_ready) to wake up vmbus_init(). So it's > not a local variable. But again, this logic should be within the init call, as it's part of the proper init sequence. So just put it in that call please. thanks, greg k-h _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
