linux-kernel - Re: [PATCH] VSOCK: Don't call vsock_stream_has

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Date:   Fri, 24 Nov 2017 01:29:23 +0900 (KST)
From:   David Miller <davem@...emloft.net>
To:     jhansen@...are.com
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        gregkh@...uxfoundation.org, pv-drivers@...are.com
Subject: Re: [PATCH] VSOCK: Don't call vsock_stream_has_data in atomic
 context

From: Jorgen Hansen <jhansen@...are.com>
Date: Tue, 21 Nov 2017 02:46:24 -0800

> When using the host personality, VMCI will grab a mutex for any
> queue pair access. In the detach callback for the vmci vsock
> transport, we call vsock_stream_has_data while holding a spinlock,
> and vsock_stream_has_data will access a queue pair.
> 
> To avoid this, we can simply omit calling vsock_stream_has_data
> for host side queue pairs, since the QPs are empty per default
> when the guest has detached.
> 
> This bug affects users of VMware Workstation using kernel version
> 4.4 and later.
> 
> Testing: Ran vsock tests between guest and host, and verified that
> with this change, the host isn't calling vsock_stream_has_data
> during detach. Ran mixedTest between guest and host using both
> guest and host as server.
> 
> Reviewed-by: Adit Ranadive <aditr@...are.com>
> Reviewed-by: Aditya Sarwade <asarwade@...are.com>
> Signed-off-by: Jorgen Hansen <jhansen@...are.com>

This doesn't apply cleanly to the current 'net' GIT tree.