[PATCH 0/5] rcu_barrier: Resubmitting the the networking bits

[PATCH 0/5] rcu_barrier: Resubmitting the the networking bits

[Jesper Dangaard Brouer]

(This time I don't use "stg mail --auto" as it does not seem to do
appropiate double quoting of mail addresses with a "." char in.
Thus hoping vger will not eat my mails again again!)

This patchset is a resubmit of the network related part of a patchseries
titled "We must use rcu_barrier() on module unload".  Just to make it
easier for DaveM to pick it up.

If an unloadable module uses RCU callbacks, it need to use
rcu_barrier() so that the module may be safely unloaded.

For documentation see:

 Paul E. McKenney's Blog
 http://paulmck.livejournal.com/7314.html

 http://lwn.net/Articles/217484/

 Documentation/RCU/rcubarrier.txt

Patchset is made on top of Linus'es tree, 4075ea8c54a7506844a69f674990241e7766357b.
But I have testet is applies to net-next-2.6.

---

Jesper Dangaard Brouer (5):
      decnet: Use rcu_barrier() on module unload.
      ipv6: Use rcu_barrier() on module unload.
      sunrpc: Use rcu_barrier() on unload.
      mac80211: Use rcu_barrier() on unload.
      bridge: Use rcu_barrier() instead of syncronize_net() on unload.


 net/bridge/br.c          |    2 +-
 net/decnet/af_decnet.c   |    2 ++
 net/ipv6/af_inet6.c      |    2 ++
 net/mac80211/mesh.c      |    2 +-
 net/sunrpc/sunrpc_syms.c |    1 +
 5 files changed, 7 insertions(+), 2 deletions(-)

-- 
Best regards,
  Jesper Brouer
  ComX Networks A/S
  Linux Network developer
  Cand. Scient Datalog / MSc.
  Author of http://adsl-optimizer.dk

[PATCH 1/5] bridge: Use rcu_barrier() instead of syncronize_net() on unload.

[Jesper Dangaard Brouer]

When unloading modules that uses call_rcu() callbacks, then we must
use rcu_barrier().  This module uses syncronize_net() which is not
enough to be sure that all callback has been completed.

Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
---

 net/bridge/br.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/bridge/br.c b/net/bridge/br.c
index 9aac521..e1241c7 100644
--- a/net/bridge/br.c
+++ b/net/bridge/br.c
@@ -93,7 +93,7 @@ static void __exit br_deinit(void)
 
 	unregister_pernet_subsys(&br_net_ops);
 
-	synchronize_net();
+	rcu_barrier(); /* Wait for completion of call_rcu()'s */
 
 	br_netfilter_fini();
 #if defined(CONFIG_ATM_LANE) || defined(CONFIG_ATM_LANE_MODULE)

[PATCH 2/5] mac80211: Use rcu_barrier() on unload.

[Jesper Dangaard Brouer]

The mac80211 module uses rcu_call() thus it should use rcu_barrier()
on module unload.

The rcu_barrier() is placed in mech.c ieee80211_stop_mesh() which is
invoked from ieee80211_stop() in case vif.type == NL80211_IFTYPE_MESH_POINT.

Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
---

 net/mac80211/mesh.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
index fc712e6..11cf45b 100644
--- a/net/mac80211/mesh.c
+++ b/net/mac80211/mesh.c
@@ -494,7 +494,7 @@ void ieee80211_stop_mesh(struct ieee80211_sub_if_data *sdata)
 	 * should it be using the interface and enqueuing
 	 * frames at this very time on another CPU.
 	 */
-	synchronize_rcu();
+	rcu_barrier(); /* Wait for RX path and call_rcu()'s */
 	skb_queue_purge(&sdata->u.mesh.skb_queue);
 }
 

[PATCH 3/5] sunrpc: Use rcu_barrier() on unload.

[Jesper Dangaard Brouer]

The sunrpc module uses rcu_call() thus it should use rcu_barrier() on
module unload.

Have not verified that the possibility for new call_rcu() callbacks
has been disabled.  As a hint for checking, the functions calling
call_rcu() (unx_destroy_cred and generic_destroy_cred) are
registered as crdestroy function pointer in struct rpc_credops.

Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
---

 net/sunrpc/sunrpc_syms.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/net/sunrpc/sunrpc_syms.c b/net/sunrpc/sunrpc_syms.c
index 843629f..adaa819 100644
--- a/net/sunrpc/sunrpc_syms.c
+++ b/net/sunrpc/sunrpc_syms.c
@@ -66,6 +66,7 @@ cleanup_sunrpc(void)
 #ifdef CONFIG_PROC_FS
 	rpc_proc_exit();
 #endif
+	rcu_barrier(); /* Wait for completion of call_rcu()'s */
 }
 MODULE_LICENSE("GPL");
 module_init(init_sunrpc);

[PATCH 4/5] ipv6: Use rcu_barrier() on module unload.

[Jesper Dangaard Brouer]

The ipv6 module uses rcu_call() thus it should use rcu_barrier() on
module unload.

Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
---

 net/ipv6/af_inet6.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 85b3d00..caa0278 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -1284,6 +1284,8 @@ static void __exit inet6_exit(void)
 	proto_unregister(&udplitev6_prot);
 	proto_unregister(&udpv6_prot);
 	proto_unregister(&tcpv6_prot);
+
+	rcu_barrier(); /* Wait for completion of call_rcu()'s */
 }
 module_exit(inet6_exit);
 

[PATCH 5/5] decnet: Use rcu_barrier() on module unload.

[Jesper Dangaard Brouer]

The decnet module unloading as been disabled with a '#if 0' statement,
because it have had issues.

We add a rcu_barrier() anyhow for correctness.

The maintainer (Chrissie Caulfield) will look into the unload issue
when time permits.

Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Chrissie Caulfield <christine.caulfield@googlemail.com>
Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
---

 net/decnet/af_decnet.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/net/decnet/af_decnet.c b/net/decnet/af_decnet.c
index d351b8d..77d4028 100644
--- a/net/decnet/af_decnet.c
+++ b/net/decnet/af_decnet.c
@@ -2413,6 +2413,8 @@ static void __exit decnet_exit(void)
 	proc_net_remove(&init_net, "decnet");
 
 	proto_unregister(&dn_proto);
+
+	rcu_barrier_bh(); /* Wait for completion of call_rcu_bh()'s */
 }
 module_exit(decnet_exit);
 #endif

Re: [PATCH 0/5] rcu_barrier: Resubmitting the the networking bits

[David Miller]

From: Jesper Dangaard Brouer <hawk@comx.dk>
Date: Fri, 26 Jun 2009 22:45:43 +0200

> This patchset is a resubmit of the network related part of a patchseries
> titled "We must use rcu_barrier() on module unload".  Just to make it
> easier for DaveM to pick it up.
> 
> If an unloadable module uses RCU callbacks, it need to use
> rcu_barrier() so that the module may be safely unloaded.

All applied, thanks a lot!