linux-kernel - RE: [PATCH v2] Drivers: hv: vmbus: Ignore CHANNELMSG_TL_CONNECT

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Message-ID: <MW2PR2101MB1052AEC27FF7287F5BA81C91D7320@MW2PR2101MB1052.namprd21.prod.outlook.com>
Date:   Mon, 20 Jan 2020 00:51:51 +0000
From:   Michael Kelley <mikelley@...rosoft.com>
To:     Dexuan Cui <decui@...rosoft.com>,
        KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        "sashal@...nel.org" <sashal@...nel.org>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
CC:     Sunil Muthuswamy <sunilmut@...rosoft.com>,
        Andrea Parri <Andrea.Parri@...rosoft.com>,
        Wei Hu <weh@...rosoft.com>
Subject: RE: [PATCH v2] Drivers: hv: vmbus: Ignore
 CHANNELMSG_TL_CONNECT_RESULT(23)

From: Dexuan Cui <decui@...rosoft.com> Sent: Sunday, January 19, 2020 3:29 PM
> 
> When a Linux hv_sock app tries to connect to a Service GUID on which no
> host app is listening, a recent host (RS3+) sends a
> CHANNELMSG_TL_CONNECT_RESULT (23) message to Linux and this triggers such
> a warning:
> 
> unknown msgtype=23
> WARNING: CPU: 2 PID: 0 at drivers/hv/vmbus_drv.c:1031 vmbus_on_msg_dpc
> 
> Actually Linux can safely ignore the message because the Linux app's
> connect() will time out in 2 seconds: see VSOCK_DEFAULT_CONNECT_TIMEOUT
> and vsock_stream_connect(). We don't bother to make use of the message
> because: 1) it's only supported on recent hosts; 2) a non-trivial effort
> is required to use the message in Linux, but the benefit is small.
> 
> So, let's not see the warning by silently ignoring the message.
> 
> Signed-off-by: Dexuan Cui <decui@...rosoft.com>
> ---
> 
> In v2 (followed Michael Kelley's suggestions):
>     Removed the redundant code in vmbus_onmessage()
>     Added the new enries into channel_message_table[].
> 
>  drivers/hv/channel_mgmt.c | 21 +++++++--------------
>  drivers/hv/vmbus_drv.c    |  4 ++++
>  include/linux/hyperv.h    |  2 ++
>  3 files changed, 13 insertions(+), 14 deletions(-)
> 

Reviewed-by: Michael Kelley <mikelley@...rosoft.com>