* [Bridge] [PATCH 2/7] netpoll: make __netpoll_cleanup non-block
[not found] <1343403484-29347-1-git-send-email-amwang@redhat.com>
@ 2012-07-27 15:37 ` Cong Wang
2012-07-27 18:40 ` Neil Horman
2012-07-27 15:38 ` [Bridge] [PATCH 4/7] bridge: call NETDEV_RELEASE notifier in br_del_if() Cong Wang
1 sibling, 1 reply; 6+ messages in thread
From: Cong Wang @ 2012-07-27 15:37 UTC (permalink / raw)
To: netdev
Cc: bridge, Jiri Pirko, Cong Wang, Neil Horman, Jay Vosburgh,
linux-kernel, David S. Miller, Eric Dumazet, Joe Perches,
Cong Wang, Stephen Hemminger
Like the previous patch, slave_disable_netpoll() and __netpoll_cleanup()
may be called with read_lock() held too, so we should make them
non-block, by moving the cleanup and kfree() to call_rcu_bh() callbacks.
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
---
drivers/net/bonding/bond_main.c | 4 +--
include/linux/netpoll.h | 3 ++
net/8021q/vlan_dev.c | 6 +----
net/bridge/br_device.c | 6 +----
net/core/netpoll.c | 42 +++++++++++++++++++++++++++++---------
5 files changed, 38 insertions(+), 23 deletions(-)
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index ab773d4..9907889 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1257,9 +1257,7 @@ static inline void slave_disable_netpoll(struct slave *slave)
return;
slave->np = NULL;
- synchronize_rcu_bh();
- __netpoll_cleanup(np);
- kfree(np);
+ __netpoll_free_rcu(np);
}
static inline bool slave_dev_support_netpoll(struct net_device *slave_dev)
{
diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index 28f5389..5011d74 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -23,6 +23,7 @@ struct netpoll {
u8 remote_mac[ETH_ALEN];
struct list_head rx; /* rx_np list element */
+ struct rcu_head rcu;
};
struct netpoll_info {
@@ -38,6 +39,7 @@ struct netpoll_info {
struct delayed_work tx_work;
struct netpoll *netpoll;
+ struct rcu_head rcu;
};
void netpoll_send_udp(struct netpoll *np, const char *msg, int len);
@@ -48,6 +50,7 @@ int netpoll_setup(struct netpoll *np);
int netpoll_trap(void);
void netpoll_set_trap(int trap);
void __netpoll_cleanup(struct netpoll *np);
+void __netpoll_free_rcu(struct netpoll *np);
void netpoll_cleanup(struct netpoll *np);
int __netpoll_rx(struct sk_buff *skb);
void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index 73a2a83..43e14a2 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -703,11 +703,7 @@ static void vlan_dev_netpoll_cleanup(struct net_device *dev)
info->netpoll = NULL;
- /* Wait for transmitting packets to finish before freeing. */
- synchronize_rcu_bh();
-
- __netpoll_cleanup(netpoll);
- kfree(netpoll);
+ __netpoll_free_rcu(netpoll);
}
#endif /* CONFIG_NET_POLL_CONTROLLER */
diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index 3334845..bb6a5dd 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -267,11 +267,7 @@ void br_netpoll_disable(struct net_bridge_port *p)
p->np = NULL;
- /* Wait for transmitting packets to finish before freeing. */
- synchronize_rcu_bh();
-
- __netpoll_cleanup(np);
- kfree(np);
+ __netpoll_free_rcu(np);
}
#endif
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index c78a966..19dddef 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -878,6 +878,24 @@ static int __init netpoll_init(void)
}
core_initcall(netpoll_init);
+static void rcu_cleanup_netpoll_info(struct rcu_head *rcu_head)
+{
+ struct netpoll_info *npinfo =
+ container_of(rcu_head, struct netpoll_info, rcu);
+
+ skb_queue_purge(&npinfo->arp_tx);
+ skb_queue_purge(&npinfo->txq);
+
+ /* we can't call cancel_delayed_work_sync here, as we are in softirq*/
+ cancel_delayed_work(&npinfo->tx_work);
+
+ /* clean after last, unfinished work */
+ __skb_queue_purge(&npinfo->txq);
+ /* now cancel it again */
+ cancel_delayed_work(&npinfo->tx_work);
+ kfree(npinfo);
+}
+
void __netpoll_cleanup(struct netpoll *np)
{
struct netpoll_info *npinfo;
@@ -903,20 +921,24 @@ void __netpoll_cleanup(struct netpoll *np)
ops->ndo_netpoll_cleanup(np->dev);
RCU_INIT_POINTER(np->dev->npinfo, NULL);
+ call_rcu_bh(&npinfo->rcu, rcu_cleanup_netpoll_info);
+ }
+}
+EXPORT_SYMBOL_GPL(__netpoll_cleanup);
- /* avoid racing with NAPI reading npinfo */
- synchronize_rcu_bh();
+static void rcu_cleanup_netpoll(struct rcu_head *rcu_head)
+{
+ struct netpoll *np = container_of(rcu_head, struct netpoll, rcu);
- skb_queue_purge(&npinfo->arp_tx);
- skb_queue_purge(&npinfo->txq);
- cancel_delayed_work_sync(&npinfo->tx_work);
+ __netpoll_cleanup(np);
+ kfree(np);
+}
- /* clean after last, unfinished work */
- __skb_queue_purge(&npinfo->txq);
- kfree(npinfo);
- }
+void __netpoll_free_rcu(struct netpoll *np)
+{
+ call_rcu_bh(&np->rcu, rcu_cleanup_netpoll);
}
-EXPORT_SYMBOL_GPL(__netpoll_cleanup);
+EXPORT_SYMBOL_GPL(__netpoll_free_rcu);
void netpoll_cleanup(struct netpoll *np)
{
--
1.7.7.6
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [Bridge] [PATCH 4/7] bridge: call NETDEV_RELEASE notifier in br_del_if()
[not found] <1343403484-29347-1-git-send-email-amwang@redhat.com>
2012-07-27 15:37 ` [Bridge] [PATCH 2/7] netpoll: make __netpoll_cleanup non-block Cong Wang
@ 2012-07-27 15:38 ` Cong Wang
2012-07-27 15:50 ` Stephen Hemminger
1 sibling, 1 reply; 6+ messages in thread
From: Cong Wang @ 2012-07-27 15:38 UTC (permalink / raw)
To: netdev; +Cc: linux-kernel, Stephen Hemminger, bridge, Cong Wang,
David S. Miller
When a bridge interface deletes its underlying ports, it should
notify netconsole too, like what bonding interface does.
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
---
net/bridge/br_if.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index e1144e1..d243914 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -427,6 +427,7 @@ int br_del_if(struct net_bridge *br, struct net_device *dev)
if (!p || p->br != br)
return -EINVAL;
+ call_netdevice_notifiers(NETDEV_RELEASE, br->dev);
del_nbp(p);
spin_lock_bh(&br->lock);
--
1.7.7.6
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [Bridge] [PATCH 4/7] bridge: call NETDEV_RELEASE notifier in br_del_if()
2012-07-27 15:38 ` [Bridge] [PATCH 4/7] bridge: call NETDEV_RELEASE notifier in br_del_if() Cong Wang
@ 2012-07-27 15:50 ` Stephen Hemminger
2012-07-30 1:59 ` Cong Wang
0 siblings, 1 reply; 6+ messages in thread
From: Stephen Hemminger @ 2012-07-27 15:50 UTC (permalink / raw)
To: Cong Wang; +Cc: netdev, bridge, David S. Miller, linux-kernel
On Fri, 27 Jul 2012 23:38:01 +0800
Cong Wang <amwang@redhat.com> wrote:
> When a bridge interface deletes its underlying ports, it should
> notify netconsole too, like what bonding interface does.
>
> Cc: "David S. Miller" <davem@davemloft.net>
> Signed-off-by: Cong Wang <amwang@redhat.com>
> ---
> net/bridge/br_if.c | 1 +
> 1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
> index e1144e1..d243914 100644
> --- a/net/bridge/br_if.c
> +++ b/net/bridge/br_if.c
> @@ -427,6 +427,7 @@ int br_del_if(struct net_bridge *br, struct net_device *dev)
> if (!p || p->br != br)
> return -EINVAL;
>
> + call_netdevice_notifiers(NETDEV_RELEASE, br->dev);
> del_nbp(p);
>
> spin_lock_bh(&br->lock);
Since you can have multiple ports attached to the bridge, this
doesn't seem correct. Don't you want the netconsole to keep going
on the other ports of the bridge?
What exactly is the problem with having netconsole persist?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Bridge] [PATCH 2/7] netpoll: make __netpoll_cleanup non-block
2012-07-27 15:37 ` [Bridge] [PATCH 2/7] netpoll: make __netpoll_cleanup non-block Cong Wang
@ 2012-07-27 18:40 ` Neil Horman
2012-07-30 1:42 ` Cong Wang
0 siblings, 1 reply; 6+ messages in thread
From: Neil Horman @ 2012-07-27 18:40 UTC (permalink / raw)
To: Cong Wang
Cc: bridge, Jiri Pirko, netdev, Jay Vosburgh, linux-kernel,
Patrick McHardy, Eric Dumazet, Joe Perches, Cong Wang,
Stephen Hemminger, David S. Miller
On Fri, Jul 27, 2012 at 11:37:59PM +0800, Cong Wang wrote:
> Like the previous patch, slave_disable_netpoll() and __netpoll_cleanup()
> may be called with read_lock() held too, so we should make them
> non-block, by moving the cleanup and kfree() to call_rcu_bh() callbacks.
>
> Cc: "David S. Miller" <davem@davemloft.net>
> Signed-off-by: Cong Wang <amwang@redhat.com>
> ---
> drivers/net/bonding/bond_main.c | 4 +--
> include/linux/netpoll.h | 3 ++
> net/8021q/vlan_dev.c | 6 +----
> net/bridge/br_device.c | 6 +----
> net/core/netpoll.c | 42 +++++++++++++++++++++++++++++---------
> 5 files changed, 38 insertions(+), 23 deletions(-)
><snip>
> struct netpoll_info *npinfo;
> @@ -903,20 +921,24 @@ void __netpoll_cleanup(struct netpoll *np)
> ops->ndo_netpoll_cleanup(np->dev);
>
> RCU_INIT_POINTER(np->dev->npinfo, NULL);
> + call_rcu_bh(&npinfo->rcu, rcu_cleanup_netpoll_info);
> + }
> +}
> +EXPORT_SYMBOL_GPL(__netpoll_cleanup);
>
> - /* avoid racing with NAPI reading npinfo */
> - synchronize_rcu_bh();
> +static void rcu_cleanup_netpoll(struct rcu_head *rcu_head)
> +{
> + struct netpoll *np = container_of(rcu_head, struct netpoll, rcu);
>
> - skb_queue_purge(&npinfo->arp_tx);
> - skb_queue_purge(&npinfo->txq);
> - cancel_delayed_work_sync(&npinfo->tx_work);
> + __netpoll_cleanup(np);
> + kfree(np);
> +}
>
> - /* clean after last, unfinished work */
> - __skb_queue_purge(&npinfo->txq);
> - kfree(npinfo);
> - }
> +void __netpoll_free_rcu(struct netpoll *np)
> +{
> + call_rcu_bh(&np->rcu, rcu_cleanup_netpoll);
Here, and above I see you using an rcu_head to defer cleanup, until after all
pointer uses are dropped, but I don't see any modification of code points that
dereference any struct netpoll pointers to include
rcu_read_lock()/rcu_read_unlock(). Without those using rcu to defer cleanup is
pointless, as the rcu code won't know when its safe to run. You're no better
off that you would be just calling __netpoll_cleanup directly.
Neil
> }
> -EXPORT_SYMBOL_GPL(__netpoll_cleanup);
> +EXPORT_SYMBOL_GPL(__netpoll_free_rcu);
>
> void netpoll_cleanup(struct netpoll *np)
> {
> --
> 1.7.7.6
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Bridge] [PATCH 2/7] netpoll: make __netpoll_cleanup non-block
2012-07-27 18:40 ` Neil Horman
@ 2012-07-30 1:42 ` Cong Wang
0 siblings, 0 replies; 6+ messages in thread
From: Cong Wang @ 2012-07-30 1:42 UTC (permalink / raw)
To: Neil Horman
Cc: bridge, Jiri Pirko, netdev, Jay Vosburgh, linux-kernel,
Eric Dumazet, Joe Perches, Cong Wang, Stephen Hemminger,
David S. Miller
On Fri, 2012-07-27 at 14:40 -0400, Neil Horman wrote:
> Here, and above I see you using an rcu_head to defer cleanup, until after all
> pointer uses are dropped, but I don't see any modification of code points that
> dereference any struct netpoll pointers to include
> rcu_read_lock()/rcu_read_unlock(). Without those using rcu to defer cleanup is
> pointless, as the rcu code won't know when its safe to run. You're no better
> off that you would be just calling __netpoll_cleanup directly.
Hi, Neil,
Actually they are protected by rcu_read_lock_bh() which is implied by
local_irq_disable(), see:
commit f0f9deae9e7c421fa0c1c627beb8e174325e1ba7
Author: Herbert Xu <herbert@gondor.apana.org.au>
Date: Fri Sep 17 16:55:03 2010 -0700
netpoll: Disable IRQ around RCU dereference in netpoll_rx
We cannot use rcu_dereference_bh safely in netpoll_rx as we may
be called with IRQs disabled. We could however simply disable
IRQs as that too causes BH to be disabled and is safe in either
case.
Thanks to John Linville for discovering this bug and providing
a patch.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Thanks.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Bridge] [PATCH 4/7] bridge: call NETDEV_RELEASE notifier in br_del_if()
2012-07-27 15:50 ` Stephen Hemminger
@ 2012-07-30 1:59 ` Cong Wang
0 siblings, 0 replies; 6+ messages in thread
From: Cong Wang @ 2012-07-30 1:59 UTC (permalink / raw)
To: Stephen Hemminger; +Cc: netdev, bridge, David S. Miller, linux-kernel
On Fri, 2012-07-27 at 08:50 -0700, Stephen Hemminger wrote:
> On Fri, 27 Jul 2012 23:38:01 +0800
> Cong Wang <amwang@redhat.com> wrote:
>
> > When a bridge interface deletes its underlying ports, it should
> > notify netconsole too, like what bonding interface does.
> >
> > Cc: "David S. Miller" <davem@davemloft.net>
> > Signed-off-by: Cong Wang <amwang@redhat.com>
> > ---
> > net/bridge/br_if.c | 1 +
> > 1 files changed, 1 insertions(+), 0 deletions(-)
> >
> > diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
> > index e1144e1..d243914 100644
> > --- a/net/bridge/br_if.c
> > +++ b/net/bridge/br_if.c
> > @@ -427,6 +427,7 @@ int br_del_if(struct net_bridge *br, struct net_device *dev)
> > if (!p || p->br != br)
> > return -EINVAL;
> >
> > + call_netdevice_notifiers(NETDEV_RELEASE, br->dev);
> > del_nbp(p);
> >
> > spin_lock_bh(&br->lock);
>
> Since you can have multiple ports attached to the bridge, this
> doesn't seem correct. Don't you want the netconsole to keep going
> on the other ports of the bridge?
>
> What exactly is the problem with having netconsole persist?
Hmm, I saw an incorrect log message when deleting the last port from the
bridge when netconsole is setup on it. After rethinking it today, you
are right we should not simply disable netconsole when one port is
detached, as we have no way to know if that port is used to reach the
netconsole server.
So, please ignore this patch.
Thanks.
^ permalink raw reply [flat|nested] 6+ messages in thread
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[not found] <1343403484-29347-1-git-send-email-amwang@redhat.com>
2012-07-27 15:37 ` [Bridge] [PATCH 2/7] netpoll: make __netpoll_cleanup non-block Cong Wang
2012-07-27 18:40 ` Neil Horman
2012-07-30 1:42 ` Cong Wang
2012-07-27 15:38 ` [Bridge] [PATCH 4/7] bridge: call NETDEV_RELEASE notifier in br_del_if() Cong Wang
2012-07-27 15:50 ` Stephen Hemminger
2012-07-30 1:59 ` Cong Wang
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