linux-kernel - Re: [PATCH v2] inet: fix possible seqlock deadlocks

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Date:	Fri, 29 Nov 2013 02:08:29 +0000 (GMT)
From:	Jongman Heo <jongman.heo@...sung.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	David Miller <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>
Subject: Re: [PATCH v2] inet: fix possible seqlock deadlocks

 
------ Original Message -------
Sender : Eric Dumazet<eric.dumazet@...il.com>
Date : 2013-11-29 02:51 (GMT+09:00)
Title : [PATCH v2] inet: fix possible seqlock deadlocks
> 
> From: Eric Dumazet 
> 
> In commit c9e9042994d3 ("ipv4: fix possible seqlock deadlock") I left
> another places where IP_INC_STATS_BH() were improperly used.
> 
> udp_sendmsg(), ping_v4_sendmsg() and tcp_v4_connect() are called from
> process context, not from softirq context.
> 
> This was detected by lockdep seqlock support.
> 
> Reported-by: jongman heo 
> Fixes: 584bdf8cbdf6 ("[IPV4]: Fix "ipOutNoRoutes" counter error for TCP and UDP")
> Fixes: c319b4d76b9e ("net: ipv4: add IPPROTO_ICMP socket kind")
> Signed-off-by: Eric Dumazet 
> Cc: Hannes Frederic Sowa 
> ---
> net/ipv4/ping.c     |    2 +-
> net/ipv4/tcp_ipv4.c |    2 +-
> net/ipv4/udp.c      |    2 +-
> 3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
> index 840cf1b9e6ee..242e7f4ed6f4 100644
> --- a/net/ipv4/ping.c
> +++ b/net/ipv4/ping.c
> @@ -772,7 +772,7 @@ int ping_v4_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
> err = PTR_ERR(rt);
> rt = NULL;
> if (err == -ENETUNREACH)
> - IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
> + IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
> goto out;
> }
> 
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index 59a6f8b90cd9..067213924751 100644
> --- a/net/ipv4/tcp_ipv4.c
> +++ b/net/ipv4/tcp_ipv4.c
> @@ -177,7 +177,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> if (IS_ERR(rt)) {
> err = PTR_ERR(rt);
> if (err == -ENETUNREACH)
> - IP_INC_STATS_BH(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
> + IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
> return err;
> }
> 
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index 44dfaa09b584..44e3884f9e4c 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -999,7 +999,7 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
> err = PTR_ERR(rt);
> rt = NULL;
> if (err == -ENETUNREACH)
> - IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
> + IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
> goto out;
> }
> 

Hi, Eric,

I've applied your patch, and will let you know the result, after a full day or half day test.
Usually the issue happens within 10 minutes after boot, but to be sure...

Regards,
Jongman Heo.