linux-kernel - Re: [PATCH v6] Drivers: hv: vmbus: Expose monitor data only when monitor pages are used

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Date:   Wed, 20 Mar 2019 23:57:05 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     Kimberly Brown <kimbrownkd@...il.com>
Cc:     Michael Kelley <mikelley@...rosoft.com>,
        Long Li <longli@...rosoft.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Dexuan Cui <decui@...rosoft.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6] Drivers: hv: vmbus: Expose monitor data only when
 monitor pages are used

On Tue, Mar 19, 2019 at 12:04:01AM -0400, Kimberly Brown wrote:
>There are two methods for signaling the host: the monitor page mechanism
>and hypercalls. The monitor page mechanism is used by performance
>critical channels (storage, networking, etc.) because it provides
>improved throughput. However, latency is increased. Monitor pages are
>allocated to these channels.
>
>Monitor pages are not allocated to channels that do not use the monitor
>page mechanism. Therefore, these channels do not have a valid monitor id
>or valid monitor page data. In these cases, some of the "_show"
>functions return incorrect data. They return an invalid monitor id and
>data that is beyond the bounds of the hv_monitor_page array fields.
>
>The "channel->offermsg.monitor_allocated" value can be used to determine
>whether monitor pages have been allocated to a channel.
>
>Add "is_visible()" callback functions for the device-level and
>channel-level attribute groups. These functions will hide the monitor
>sysfs files when the monitor mechanism is not used.
>
>Remove ".default_attributes" from "vmbus_chan_attrs" and create a
>channel-level attribute group. These changes allow the new
>"is_visible()" callback function to be applied to the channel-level
>attributes.
>
>Call "sysfs_create_group()" in "vmbus_add_channel_kobj()" to create the
>channel's sysfs files. Add a new function,
>“vmbus_remove_channel_attr_group()”, and call it in "free_channel()" to
>remove the channel's sysfs files when the channel is closed.
>
>Signed-off-by: Kimberly Brown <kimbrownkd@...il.com>

I've queued it up for hyperv-fixes, thanks Kimberly.

Should this go in stable as well?

--
Thanks,
Sasha