From: Kaiwen Xu <kaiwen.xu@hulu.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: David Miller <davem@davemloft.net>,
Linux Kernel Network Developers <netdev@vger.kernel.org>
Subject: Re: [PATCH net v2] net: Do not hold the reference for the same sk_rx_dst
Date: Sat, 18 Mar 2017 21:03:54 -0700 [thread overview]
Message-ID: <20170319040354.GA59612@kevinmbp.test.hulu.com> (raw)
In-Reply-To: <CAM_iQpXFY+isbSR71GWyf_=-o-LEB6Ftj6P0_5c3zf9echsGnA@mail.gmail.com>
On Sat, Mar 18, 2017 at 08:49:43PM -0700, Cong Wang wrote:
> On Sat, Mar 18, 2017 at 6:48 PM, Kevin Xu <kaiwen.xu@hulu.com> wrote:
> > In some rare cases, inet_sk_rx_dst_set() may be called multiple times
> > on the same dst, causing double refcounting. Eventually, it
> > prevents net_device to be destroyed. The bug manifested as
> >
> > unregister_netdevice: waiting for lo to become free. Usage count = 1
> >
> > in the kernel log, preventing new network namespace creation.
> >
> > Signed-off-by: Kevin Xu <kaiwen.xu@hulu.com>
>
> Don't know why you don't follow the discussion on your v1...
>
> It is protected by bh_lock_sock(), so your patch is not needed
> at all.
>
> Read net/ipv4/udp.c:
>
> 1762 /* For TCP sockets, sk_rx_dst is protected by socket lock
> 1763 * For UDP, we use xchg() to guard against concurrent changes.
> 1764 */
I probably misunderstood. Do you mean v2 patch is actually not needed or
the whole workaround is not necessary?
next prev parent reply other threads:[~2017-03-19 4:04 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-16 8:08 [PATCH] [PATCH net] net: Do not hold the reference for the same sk_rx_dst Kevin Xu
2017-03-16 10:01 ` Jakub Sitnicki
2017-03-16 10:12 ` Kevin Xu
2017-03-16 10:45 ` Jakub Sitnicki
2017-03-16 18:18 ` Kaiwen Xu
2017-03-16 18:42 ` Cong Wang
2017-03-16 18:16 ` David Miller
2017-03-19 1:48 ` [PATCH net v2] " Kevin Xu
2017-03-19 3:49 ` Cong Wang
2017-03-19 4:03 ` Kaiwen Xu [this message]
2017-03-20 4:09 ` Cong Wang
2017-03-20 21:23 ` Kaiwen Xu
2017-03-16 21:33 ` [PATCH] [PATCH net] " Eric Dumazet
2017-03-16 23:13 ` Cong Wang
2017-03-16 23:29 ` Eric Dumazet
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