linux-kernel - Re: move hyperv CHANNELMSG_UNLOAD from crashed kernel to kdump kernel

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Message-ID: <20161215135111.GD6336@aepfle.de>
Date:   Thu, 15 Dec 2016 14:51:12 +0100
From:   Olaf Hering <olaf@...fle.de>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     kys@...rosoft.com, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org, devel@...uxdriverproject.org
Subject: Re: move hyperv CHANNELMSG_UNLOAD from crashed kernel to kdump kernel

On Thu, Dec 15, Vitaly Kuznetsov wrote:

> vmbus_wait_for_unload() may be receiving a message (not necessarily the
> CHANNELMSG_UNLOAD_RESPONSE, we may see some other message) on the same
> CPU it runs and in this case wrmsrl() makes sense. In other cases it
> does nothing (neither good nor bad).

If that other cpu has interrupts disabled it may not process a pending
msg (the response may be stuck in the host queue?), and the loop can not
kick the other cpus queue if a wrmsrl is just valid for the current cpu.
If thats true, the response will not arrive in the loop.

Olaf

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