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From: Vladimir Oltean <olteanv@gmail.com>
To: Eric Dumazet <edumazet@google.com>
Cc: "David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	netdev <netdev@vger.kernel.org>,
	Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH v2 net-next 08/19] ipmr: do not acquire mrt_lock while calling ip_mr_forward()
Date: Sat, 23 Jul 2022 00:10:05 +0300	[thread overview]
Message-ID: <20220722211005.p2pfvy4qwdvolxi3@skbuf> (raw)
In-Reply-To: <CANn89iK+UO=FevJxnHN0ua17jwR__MfB_RZ_DavLdJz79eyCBw@mail.gmail.com>

On Fri, Jul 22, 2022 at 10:37:24PM +0200, Eric Dumazet wrote:
> Thanks for the report.
> 
> I guess there are multiple ways to solve this issue, one being:
> 
> diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
> index 73651d17e51f31c8755da6ac3c1c2763a99b1117..1c288a7b60132365c072874d1f811b70679a2bcb
> 100644
> --- a/net/ipv4/ipmr.c
> +++ b/net/ipv4/ipmr.c
> @@ -1004,7 +1004,9 @@ static void ipmr_cache_resolve(struct net *net,
> struct mr_table *mrt,
> 
>                         rtnl_unicast(skb, net, NETLINK_CB(skb).portid);
>                 } else {
> +                       rcu_read_lock();
>                         ip_mr_forward(net, mrt, skb->dev, skb, c, 0);
> +                       rcu_read_unlock();
>                 }
>         }
>  }
> @@ -1933,7 +1935,7 @@ static int ipmr_find_vif(const struct mr_table
> *mrt, struct net_device *dev)
>  }
> 
>  /* "local" means that we should preserve one skb (for local delivery) */
> -/* Called uner rcu_read_lock() */
> +/* Called under rcu_read_lock() */
>  static void ip_mr_forward(struct net *net, struct mr_table *mrt,
>                           struct net_device *dev, struct sk_buff *skb,
>                           struct mfc_cache *c, int local)

It sure makes lockdep stop complaining...

I just noticed that we appear to have the same problem with the
equivalent call path for ipv6: ip6mr_mfc_add -> ip6mr_cache_resolve ->
ip6_mr_forward, although I don't have smcroute or the kernel configured
for any IPv6 multicast routes right now, so I can't say for sure.

  reply	other threads:[~2022-07-22 21:10 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-23  4:34 [PATCH v2 net-next 00/19] ipmr: get rid of rwlocks Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 01/19] ip6mr: do not get a device reference in pim6_rcv() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 02/19] ipmr: add rcu protection over (struct vif_device)->dev Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 03/19] ipmr: change igmpmsg_netlink_event() prototype Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 04/19] ipmr: ipmr_cache_report() changes Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 05/19] ipmr: do not acquire mrt_lock in __pim_rcv() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 06/19] ipmr: do not acquire mrt_lock in ioctl(SIOCGETVIFCNT) Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 07/19] ipmr: do not acquire mrt_lock before calling ipmr_cache_unresolved() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 08/19] ipmr: do not acquire mrt_lock while calling ip_mr_forward() Eric Dumazet
2022-07-22 19:34   ` Vladimir Oltean
2022-07-22 20:37     ` Eric Dumazet
2022-07-22 21:10       ` Vladimir Oltean [this message]
2022-07-22 21:15         ` Vladimir Oltean
2022-06-23  4:34 ` [PATCH v2 net-next 09/19] ipmr: do not acquire mrt_lock in ipmr_get_route() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 10/19] ip6mr: ip6mr_cache_report() changes Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 11/19] ip6mr: do not acquire mrt_lock in pim6_rcv() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 12/19] ip6mr: do not acquire mrt_lock in ioctl(SIOCGETMIFCNT_IN6) Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 13/19] ip6mr: do not acquire mrt_lock before calling ip6mr_cache_unresolved Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 14/19] ip6mr: do not acquire mrt_lock while calling ip6_mr_forward() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 15/19] ip6mr: switch ip6mr_get_route() to rcu_read_lock() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 16/19] ipmr: adopt rcu_read_lock() in mr_dump() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 17/19] ipmr: convert /proc handlers to rcu_read_lock() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 18/19] ipmr: convert mrt_lock to a spinlock Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 19/19] ip6mr: " Eric Dumazet
2022-06-24 10:50 ` [PATCH v2 net-next 00/19] ipmr: get rid of rwlocks patchwork-bot+netdevbpf

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