linux-kernel - Re: [PATCH net] hv_netvsc: Fix XDP refcnt for synthetic and VF NICs

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Message-Id: <20200207.113413.1857068725421133796.davem@davemloft.net>
Date:   Fri, 07 Feb 2020 11:34:13 +0100 (CET)
From:   David Miller <davem@...emloft.net>
To:     haiyangz@...rosoft.com
Cc:     sashal@...nel.org, linux-hyperv@...r.kernel.org,
        netdev@...r.kernel.org, kys@...rosoft.com, sthemmin@...rosoft.com,
        olaf@...fle.de, vkuznets@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] hv_netvsc: Fix XDP refcnt for synthetic and VF NICs

From: Haiyang Zhang <haiyangz@...rosoft.com>
Date: Thu,  6 Feb 2020 14:01:05 -0800

> The caller of XDP_SETUP_PROG has already incremented refcnt in
> __bpf_prog_get(), so drivers should only increment refcnt by
> num_queues - 1.
> 
> To fix the issue, update netvsc_xdp_set() to add the correct number
> to refcnt.
> 
> Hold a refcnt in netvsc_xdp_set()’s other caller, netvsc_attach().
> 
> And, do the same in netvsc_vf_setxdp(). Otherwise, every time when VF is
> removed and added from the host side, the refcnt will be decreased by one,
> which may cause page fault when unloading xdp program.
> 
> Fixes: 351e1581395f ("hv_netvsc: Add XDP support")
> Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>

Applied, thank you.