From: Pavel Emelyanov <xemul@parallels.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: "Sjur Brændeland" <sjur.brandeland@stericsson.com>,
"levinsasha928@gmail.com" <levinsasha928@gmail.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"davem@davemloft.net" <davem@davemloft.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"davej@redhat.com" <davej@redhat.com>,
"sjurbren@gmail.com" <sjurbren@gmail.com>,
"Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH] netns: fix net_alloc_generic()
Date: Thu, 26 Jan 2012 14:44:14 +0400 [thread overview]
Message-ID: <4F212E7E.2040801@parallels.com> (raw)
In-Reply-To: <1327574498.2500.22.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC>
> I believe the problem is in net_namespace infrastructure, not in CAIF.
>
> Could you test following patch instead ?
>
> [PATCH] netns: fix net_alloc_generic()
>
> When a new net namespace is created, we should attach to it a "struct
> net_generic" with enough slots (even empty), or we can hit the following
> BUG_ON() :
>
> [ 200.752016] kernel BUG at include/net/netns/generic.h:40!
> ...
> [ 200.752016] [<ffffffff825c3cea>] ? get_cfcnfg+0x3a/0x180
> [ 200.752016] [<ffffffff821cf0b0>] ? lockdep_rtnl_is_held+0x10/0x20
> [ 200.752016] [<ffffffff825c41be>] caif_device_notify+0x2e/0x530
> [ 200.752016] [<ffffffff810d61b7>] notifier_call_chain+0x67/0x110
> [ 200.752016] [<ffffffff810d67c1>] raw_notifier_call_chain+0x11/0x20
> [ 200.752016] [<ffffffff821bae82>] call_netdevice_notifiers+0x32/0x60
> [ 200.752016] [<ffffffff821c2b26>] register_netdevice+0x196/0x300
> [ 200.752016] [<ffffffff821c2ca9>] register_netdev+0x19/0x30
> [ 200.752016] [<ffffffff81c1c67a>] loopback_net_init+0x4a/0xa0
> [ 200.752016] [<ffffffff821b5e62>] ops_init+0x42/0x180
> [ 200.752016] [<ffffffff821b600b>] setup_net+0x6b/0x100
> [ 200.752016] [<ffffffff821b6466>] copy_net_ns+0x86/0x110
> [ 200.752016] [<ffffffff810d5789>] create_new_namespaces+0xd9/0x190
>
> net_alloc_generic() should take into account the maximum index into the
> ptr array, as a subsystem might use net_generic() anytime.
I'm not sure I understand it correctly, but subsystem can only use the
net_generic() only (!) after the net_assign_generic() is performed.
> This also reduces number of reallocations in net_assign_generic()
>
> Reported-by: Sasha Levin <levinsasha928@gmail.com>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
> Cc: Sjur Brændeland <sjur.brandeland@stericsson.com>
> Cc: Eric W. Biederman <ebiederm@xmission.com>
> Cc: Pavel Emelyanov <xemul@openvz.org>
> ---
> net/core/net_namespace.c | 31 ++++++++++++++++---------------
> 1 file changed, 16 insertions(+), 15 deletions(-)
>
> diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
> index aefcd7a..0e950fd 100644
> --- a/net/core/net_namespace.c
> +++ b/net/core/net_namespace.c
> @@ -30,6 +30,20 @@ EXPORT_SYMBOL(init_net);
>
> #define INITIAL_NET_GEN_PTRS 13 /* +1 for len +2 for rcu_head */
>
> +static unsigned int max_gen_ptrs = INITIAL_NET_GEN_PTRS;
> +
> +static struct net_generic *net_alloc_generic(void)
> +{
> + struct net_generic *ng;
> + size_t generic_size = offsetof(struct net_generic, ptr[max_gen_ptrs]);
> +
> + ng = kzalloc(generic_size, GFP_KERNEL);
> + if (ng)
> + ng->len = max_gen_ptrs;
> +
> + return ng;
> +}
> +
> static int net_assign_generic(struct net *net, int id, void *data)
> {
> struct net_generic *ng, *old_ng;
> @@ -43,8 +57,7 @@ static int net_assign_generic(struct net *net, int id, void *data)
> if (old_ng->len >= id)
> goto assign;
>
> - ng = kzalloc(sizeof(struct net_generic) +
> - id * sizeof(void *), GFP_KERNEL);
> + ng = net_alloc_generic();
> if (ng == NULL)
> return -ENOMEM;
>
> @@ -59,7 +72,6 @@ static int net_assign_generic(struct net *net, int id, void *data)
> * the old copy for kfree after a grace period.
> */
>
> - ng->len = id;
> memcpy(&ng->ptr, &old_ng->ptr, old_ng->len * sizeof(void*));
>
> rcu_assign_pointer(net->gen, ng);
> @@ -161,18 +173,6 @@ out_undo:
> goto out;
> }
>
> -static struct net_generic *net_alloc_generic(void)
> -{
> - struct net_generic *ng;
> - size_t generic_size = sizeof(struct net_generic) +
> - INITIAL_NET_GEN_PTRS * sizeof(void *);
> -
> - ng = kzalloc(generic_size, GFP_KERNEL);
> - if (ng)
> - ng->len = INITIAL_NET_GEN_PTRS;
> -
> - return ng;
> -}
>
> #ifdef CONFIG_NET_NS
> static struct kmem_cache *net_cachep;
> @@ -483,6 +483,7 @@ again:
> }
> return error;
> }
> + max_gen_ptrs = max_t(unsigned int, max_gen_ptrs, *ops->id);
> }
> error = __register_pernet_operations(list, ops);
> if (error) {
>
>
next prev parent reply other threads:[~2012-01-26 10:45 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-24 7:30 [PATCH] net: caif: Don't act on notification for non-caif devices Sasha Levin
2012-01-24 10:52 ` Sjur Brændeland
2012-01-24 14:49 ` Sasha Levin
2012-01-24 15:06 ` Sjur Brændeland
2012-01-24 15:23 ` Sasha Levin
2012-01-24 22:27 ` [PATCH net] caif: Fix crash due to uninitialized net name-space Sjur Brændeland
2012-01-24 22:44 ` David Miller
2012-01-25 16:13 ` Sasha Levin
2012-01-25 20:33 ` Sjur Brændeland
2012-01-26 6:14 ` Eric Dumazet
2012-01-26 10:41 ` [PATCH] netns: fix net_alloc_generic() Eric Dumazet
2012-01-26 10:44 ` Pavel Emelyanov [this message]
2012-01-26 10:51 ` Eric Dumazet
2012-01-26 22:57 ` Eric W. Biederman
2012-01-26 23:07 ` David Miller
2012-01-26 23:57 ` Eric W. Biederman
2012-01-27 0:02 ` [PATCH 1/2] netns: Fail conspicously if someone uses net_generic at an inappropriate time Eric W. Biederman
2012-01-27 0:04 ` [PATCH 2/2] net caif: Register properly as a pernet subsystem Eric W. Biederman
2012-01-27 13:24 ` Sasha Levin
2012-01-27 14:48 ` Sjur BRENDELAND
2012-01-28 2:07 ` David Miller
2012-01-28 2:07 ` [PATCH 1/2] netns: Fail conspicously if someone uses net_generic at an inappropriate time David Miller
2012-01-27 6:09 ` [PATCH] netns: fix net_alloc_generic() Eric Dumazet
2012-01-27 6:54 ` Eric W. Biederman
2012-01-27 7:07 ` Eric Dumazet
2012-01-26 14:40 ` Sasha Levin
2012-01-26 18:37 ` David Miller
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