netdev - Re: [PATCH v3 2/5] vsock/virtio: fix locking for fwd_cnt and buf

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Message-ID: <20190603110717.rjbwfojpdpye3yxe@steredhat.homenet.telecomitalia.it>
Date:   Mon, 3 Jun 2019 13:07:17 +0200
From:   Stefano Garzarella <sgarzare@...hat.com>
To:     David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, stefanha@...hat.com,
        virtualization@...ts.linux-foundation.org, mst@...hat.com,
        jasowang@...hat.com, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Subject: Re: [PATCH v3 2/5] vsock/virtio: fix locking for fwd_cnt and
 buf_alloc

On Sun, Jun 02, 2019 at 06:03:34PM -0700, David Miller wrote:
> From: Stefano Garzarella <sgarzare@...hat.com>
> Date: Fri, 31 May 2019 15:39:51 +0200
> 
> > @@ -434,7 +434,9 @@ void virtio_transport_set_buffer_size(struct vsock_sock *vsk, u64 val)
> >  	if (val > vvs->buf_size_max)
> >  		vvs->buf_size_max = val;
> >  	vvs->buf_size = val;
> > +	spin_lock_bh(&vvs->rx_lock);
> >  	vvs->buf_alloc = val;
> > +	spin_unlock_bh(&vvs->rx_lock);
> 
> This locking doesn't do anything other than to strongly order the
> buf_size store to occur before the buf_alloc one.

Sure, I'll remove the lock. I was confused because I moved its reading
under the rx_lock (together with other variables), but here I'm updating
only buf_alloc, so this lock is useless.

Thanks,
Stefano