RE: [PATCH 1/1] staging: hv: Fix race condition on IC channelinitialization (modified)

[Haiyang Zhang]

> From: Greg KH [mailto:gregkh@xxxxxxx]
> > 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.
> 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...)

Actually, since the interrupts only happen on cpu0, this is not a concern. How about use a simple int variable here? Also, remove the mb().

> > 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.

The VmbusChannelProcessOffer() is called from interrupt context, and initialize the channels, wake up vmbus_init when all channels are ready. If using local variable only, how to pass the channel ready info to vmbus_init() which is in a different context?

Thanks,

- Haiyang

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