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From: Jesper Dangaard Brouer <brouer@redhat.com>
To: John Fastabend <john.fastabend@gmail.com>
Cc: brouer@redhat.com, bpf@vger.kernel.org, bjorn.topel@intel.com,
	songliubraving@fb.com, ast@kernel.org, daniel@iogearbox.net,
	toke@redhat.com, maciej.fijalkowski@intel.com,
	netdev@vger.kernel.org
Subject: Re: [PATCH bpf-next v2 2/3] bpf: xdp, virtio_net use access ptr macro for xdp enable check
Date: Sun, 26 Jan 2020 22:28:50 +0100	[thread overview]
Message-ID: <20200126222850.04aff480@carbon> (raw)
In-Reply-To: <1580011133-17784-3-git-send-email-john.fastabend@gmail.com>

On Sat, 25 Jan 2020 19:58:52 -0800
John Fastabend <john.fastabend@gmail.com> wrote:

> virtio_net currently relies on rcu critical section to access the xdp
> program in its xdp_xmit handler. However, the pointer to the xdp program
> is only used to do a NULL pointer comparison to determine if xdp is
> enabled or not.
> 
> Use rcu_access_pointer() instead of rcu_dereference() to reflect this.
> Then later when we drop rcu_read critical section virtio_net will not
> need in special handling.
> 
> Signed-off-by: John Fastabend <john.fastabend@gmail.com>

Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer


  reply	other threads:[~2020-01-26 21:29 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-26  3:58 [PATCH bpf-next v2 0/3] XDP flush cleanups John Fastabend
2020-01-26  3:58 ` [PATCH bpf-next v2 1/3] bpf: xdp, update devmap comments to reflect napi/rcu usage John Fastabend
2020-01-26 21:28   ` Jesper Dangaard Brouer
2020-01-26  3:58 ` [PATCH bpf-next v2 2/3] bpf: xdp, virtio_net use access ptr macro for xdp enable check John Fastabend
2020-01-26 21:28   ` Jesper Dangaard Brouer [this message]
2020-01-26  3:58 ` [PATCH bpf-next v2 3/3] bpf: xdp, remove no longer required rcu_read_{un}lock() John Fastabend
2020-01-26 21:30   ` Jesper Dangaard Brouer

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