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

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Message-ID: <CAJSP0QXFknaZboxeEwJmxri2Vjo1GfwK5JwDyWPgEKyi5cJp1g@mail.gmail.com>
Date:   Thu, 23 Nov 2017 10:02:05 +0000
From:   Stefan Hajnoczi <stefanha@...il.com>
To:     Jorgen Hansen <jhansen@...are.com>
Cc:     netdev@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Linux Virtualization <virtualization@...ts.linux-foundation.org>,
        pv-drivers@...are.com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        David Miller <davem@...emloft.net>
Subject: Re: [PATCH] VSOCK: Don't call vsock_stream_has_data in atomic context

On Tue, Nov 21, 2017 at 10:46 AM, Jorgen Hansen <jhansen@...are.com> wrote:
> 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>
> ---
>  net/vmw_vsock/vmci_transport.c |   10 +++++++---
>  1 files changed, 7 insertions(+), 3 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@...hat.com>