From: David Miller <davem@davemloft.net>
To: jasowang@redhat.com
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
mst@redhat.com, sergei.shtylyov@cogentembedded.com,
christoffer.dall@linaro.org, brouer@redhat.com
Subject: Re: [PATCH V4 net 2/3] tuntap: disable preemption during XDP processing
Date: Mon, 26 Feb 2018 13:50:10 -0500 (EST) [thread overview]
Message-ID: <20180226.135010.66707697236959796.davem@davemloft.net> (raw)
In-Reply-To: <1519443146-9089-2-git-send-email-jasowang@redhat.com>
From: Jason Wang <jasowang@redhat.com>
Date: Sat, 24 Feb 2018 11:32:25 +0800
> Except for tuntap, all other drivers' XDP was implemented at NAPI
> poll() routine in a bh. This guarantees all XDP operation were done at
> the same CPU which is required by e.g BFP_MAP_TYPE_PERCPU_ARRAY. But
> for tuntap, we do it in process context and we try to protect XDP
> processing by RCU reader lock. This is insufficient since
> CONFIG_PREEMPT_RCU can preempt the RCU reader critical section which
> breaks the assumption that all XDP were processed in the same CPU.
>
> Fixing this by simply disabling preemption during XDP processing.
>
> Fixes: 761876c857cb ("tap: XDP support")
> Signed-off-by: Jason Wang <jasowang@redhat.com>
Applied.
next prev parent reply other threads:[~2018-02-26 18:50 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-24 3:32 [PATCH V4 net 1/3] Revert "tuntap: add missing xdp flush" Jason Wang
2018-02-24 3:32 ` [PATCH V4 net 2/3] tuntap: disable preemption during XDP processing Jason Wang
2018-02-26 11:02 ` Jesper Dangaard Brouer
2018-02-26 13:43 ` Jason Wang
2018-02-26 18:50 ` David Miller [this message]
2018-02-24 3:32 ` [PATCH V4 net 3/3] tuntap: correctly add the missing XDP flush Jason Wang
2018-02-26 18:50 ` David Miller
2018-02-26 18:50 ` [PATCH V4 net 1/3] Revert "tuntap: add missing xdp flush" David Miller
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