* [RFC PATCH] ixgbe: acquire RCU read lock when calling netdev_for_each_all_upper_dev_rcu()
@ 2013-12-19 6:00 Jiang Liu
2013-12-19 6:38 ` John Fastabend
0 siblings, 1 reply; 2+ messages in thread
From: Jiang Liu @ 2013-12-19 6:00 UTC (permalink / raw)
To: Jeff Kirsher, Jesse Brandeburg, Bruce Allan, Carolyn Wyborny,
Don Skidmore, Greg Rose, Alex Duyck, John Ronciak,
David S. Miller, Jacob Keller
Cc: Jiang Liu, e1000-devel, netdev, linux-kernel
According to documentation for netdev_for_each_all_upper_dev_rcu(),
caller should take RCU read lock, otherwise it will trigger following
warnings. The simplest fix is to protect with rcu_read_lock()/
rcu_read_unlock(). And this solutions passes basic tests.
Otherwise we may need to introduce netdev_for_each_all_upper_dev()
as netdev_lower_get_next_private(), which assumes the caller has
gained the lock to protect the list.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
---
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index cc06854..da72a5f 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -4336,6 +4336,7 @@ static void ixgbe_configure_dfwd(struct ixgbe_adapter *adapter)
struct list_head *iter;
int err;
+ rcu_read_lock();
netdev_for_each_all_upper_dev_rcu(adapter->netdev, upper, iter) {
if (netif_is_macvlan(upper)) {
struct macvlan_dev *dfwd = netdev_priv(upper);
@@ -4348,6 +4349,7 @@ static void ixgbe_configure_dfwd(struct ixgbe_adapter *adapter)
}
}
}
+ rcu_read_unlock();
}
static void ixgbe_configure(struct ixgbe_adapter *adapter)
@@ -4601,6 +4603,7 @@ static void ixgbe_up_complete(struct ixgbe_adapter *adapter)
netif_tx_start_all_queues(adapter->netdev);
/* enable any upper devices */
+ rcu_read_lock();
netdev_for_each_all_upper_dev_rcu(adapter->netdev, upper, iter) {
if (netif_is_macvlan(upper)) {
struct macvlan_dev *vlan = netdev_priv(upper);
@@ -4609,6 +4612,7 @@ static void ixgbe_up_complete(struct ixgbe_adapter *adapter)
netif_tx_start_all_queues(upper);
}
}
+ rcu_read_unlock();
/* bring the link up in the watchdog, this could race with our first
* link up interrupt but shouldn't be a problem */
@@ -4803,6 +4807,7 @@ void ixgbe_down(struct ixgbe_adapter *adapter)
netif_tx_disable(netdev);
/* disable any upper devices */
+ rcu_read_lock();
netdev_for_each_all_upper_dev_rcu(adapter->netdev, upper, iter) {
if (netif_is_macvlan(upper)) {
struct macvlan_dev *vlan = netdev_priv(upper);
@@ -4814,6 +4819,7 @@ void ixgbe_down(struct ixgbe_adapter *adapter)
}
}
}
+ rcu_read_unlock();
ixgbe_irq_disable(adapter);
--
1.7.10.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [RFC PATCH] ixgbe: acquire RCU read lock when calling netdev_for_each_all_upper_dev_rcu()
2013-12-19 6:00 [RFC PATCH] ixgbe: acquire RCU read lock when calling netdev_for_each_all_upper_dev_rcu() Jiang Liu
@ 2013-12-19 6:38 ` John Fastabend
0 siblings, 0 replies; 2+ messages in thread
From: John Fastabend @ 2013-12-19 6:38 UTC (permalink / raw)
To: Jiang Liu
Cc: Jeff Kirsher, Jesse Brandeburg, Bruce Allan, Carolyn Wyborny,
Don Skidmore, Greg Rose, Alex Duyck, John Ronciak,
David S. Miller, Jacob Keller, e1000-devel, netdev, linux-kernel
On 12/18/2013 10:00 PM, Jiang Liu wrote:
> According to documentation for netdev_for_each_all_upper_dev_rcu(),
> caller should take RCU read lock, otherwise it will trigger following
> warnings. The simplest fix is to protect with rcu_read_lock()/
> rcu_read_unlock(). And this solutions passes basic tests.
>
> Otherwise we may need to introduce netdev_for_each_all_upper_dev()
> as netdev_lower_get_next_private(), which assumes the caller has
> gained the lock to protect the list.
>
> Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
> ---
Jiang,
The following patch addresses the same issue,
http://patchwork.ozlabs.org/patch/302711/
[net,1/5] net: allow netdev_all_upper_get_next_dev_rcu with rtnl lock held
It is under review and solves the problem by having the call check for
the rtnl lock as well. Take a look. I think it is a slightly better fix
in that it doesn't clutter the driver with unnecessary rcu_read_lock()
and rcu_read_unlock() calls.
Thanks,
John
^ permalink raw reply [flat|nested] 2+ messages in thread
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2013-12-19 6:00 [RFC PATCH] ixgbe: acquire RCU read lock when calling netdev_for_each_all_upper_dev_rcu() Jiang Liu
2013-12-19 6:38 ` John Fastabend
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