[PATCH net-next v3 5/10] bonding: create bond_first_slave_rcu()

[PATCH net-next v3 5/10] bonding: create bond_first_slave_rcu()

[Ding Tianhong]

The bond_first_slave_rcu() will be used to instead of bond_first_slave()
in rcu_read_lock().

So move the struct netdev_adjacent to the netdevice.h and make the
bond_first_slave_rcu() could use the struct.

Suggested-by: Jay Vosburgh <fubar@us.ibm.com>
Suggested-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
---
 drivers/net/bonding/bonding.h |  9 +++++++++
 include/linux/netdevice.h     | 16 ++++++++++++++++
 net/core/dev.c                | 16 ----------------
 3 files changed, 25 insertions(+), 16 deletions(-)

diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index 77a07a1..5d37606 100644
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -91,6 +91,15 @@
 		netdev_adjacent_get_private(bond_slave_list(bond)->prev) : \
 		NULL)
 
+/* Caller must have rcu_read_lock */
+#define bond_first_slave_rcu(bond) \
+	({struct list_head *__ptr = (bond_slave_list(bond)); \
+	 struct list_head *__next = ACCESS_ONCE(__ptr->next); \
+	 likely(__ptr != __next) ? \
+	 list_entry_rcu(__next, struct netdev_adjacent, list)->private : \
+		NULL; \
+	 })
+
 #define bond_is_first_slave(bond, pos) (pos == bond_first_slave(bond))
 #define bond_is_last_slave(bond, pos) (pos == bond_last_slave(bond))
 
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 15fa01c..7ca0fc8 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2839,6 +2839,22 @@ extern int		netdev_tstamp_prequeue;
 extern int		weight_p;
 extern int		bpf_jit_enable;
 
+struct netdev_adjacent {
+	struct net_device *dev;
+
+	/* upper master flag, there can only be one master device per list */
+	bool master;
+
+	/* counter for the number of times this device was added to us */
+	u16 ref_nr;
+
+	/* private field for the users */
+	void *private;
+
+	struct list_head list;
+	struct rcu_head rcu;
+};
+
 bool netdev_has_upper_dev(struct net_device *dev, struct net_device *upper_dev);
 bool netdev_has_any_upper_dev(struct net_device *dev);
 struct net_device *netdev_all_upper_get_next_dev_rcu(struct net_device *dev,
diff --git a/net/core/dev.c b/net/core/dev.c
index 8ffc52e..bcc5001 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4377,22 +4377,6 @@ softnet_break:
 	goto out;
 }
 
-struct netdev_adjacent {
-	struct net_device *dev;
-
-	/* upper master flag, there can only be one master device per list */
-	bool master;
-
-	/* counter for the number of times this device was added to us */
-	u16 ref_nr;
-
-	/* private field for the users */
-	void *private;
-
-	struct list_head list;
-	struct rcu_head rcu;
-};
-
 static struct netdev_adjacent *__netdev_find_adj_rcu(struct net_device *dev,
 						     struct net_device *adj_dev,
 						     struct list_head *adj_list)
-- 
1.8.2.1

Re: [PATCH net-next v3 5/10] bonding: create bond_first_slave_rcu()

[Veaceslav Falico]

On Mon, Nov 11, 2013 at 08:36:41PM +0800, Ding Tianhong wrote:
>The bond_first_slave_rcu() will be used to instead of bond_first_slave()
>in rcu_read_lock().
>
>So move the struct netdev_adjacent to the netdevice.h and make the
>bond_first_slave_rcu() could use the struct.

The whole point in netdev_adjacent functions was to hide it from the users
who wanted to use it directly. See

http://www.spinics.net/lists/netdev/msg248026.html

for reference. Please try to avoid that.

>
>Suggested-by: Jay Vosburgh <fubar@us.ibm.com>
>Suggested-by: Veaceslav Falico <vfalico@redhat.com>
>Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
>---
> drivers/net/bonding/bonding.h |  9 +++++++++
> include/linux/netdevice.h     | 16 ++++++++++++++++
> net/core/dev.c                | 16 ----------------
> 3 files changed, 25 insertions(+), 16 deletions(-)
>
>diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
>index 77a07a1..5d37606 100644
>--- a/drivers/net/bonding/bonding.h
>+++ b/drivers/net/bonding/bonding.h
>@@ -91,6 +91,15 @@
> 		netdev_adjacent_get_private(bond_slave_list(bond)->prev) : \
> 		NULL)
>
>+/* Caller must have rcu_read_lock */
>+#define bond_first_slave_rcu(bond) \
>+	({struct list_head *__ptr = (bond_slave_list(bond)); \
>+	 struct list_head *__next = ACCESS_ONCE(__ptr->next); \
>+	 likely(__ptr != __next) ? \
>+	 list_entry_rcu(__next, struct netdev_adjacent, list)->private : \
>+		NULL; \
>+	 })
>+
> #define bond_is_first_slave(bond, pos) (pos == bond_first_slave(bond))
> #define bond_is_last_slave(bond, pos) (pos == bond_last_slave(bond))
>
>diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
>index 15fa01c..7ca0fc8 100644
>--- a/include/linux/netdevice.h
>+++ b/include/linux/netdevice.h
>@@ -2839,6 +2839,22 @@ extern int		netdev_tstamp_prequeue;
> extern int		weight_p;
> extern int		bpf_jit_enable;
>
>+struct netdev_adjacent {
>+	struct net_device *dev;
>+
>+	/* upper master flag, there can only be one master device per list */
>+	bool master;
>+
>+	/* counter for the number of times this device was added to us */
>+	u16 ref_nr;
>+
>+	/* private field for the users */
>+	void *private;
>+
>+	struct list_head list;
>+	struct rcu_head rcu;
>+};
>+
> bool netdev_has_upper_dev(struct net_device *dev, struct net_device *upper_dev);
> bool netdev_has_any_upper_dev(struct net_device *dev);
> struct net_device *netdev_all_upper_get_next_dev_rcu(struct net_device *dev,
>diff --git a/net/core/dev.c b/net/core/dev.c
>index 8ffc52e..bcc5001 100644
>--- a/net/core/dev.c
>+++ b/net/core/dev.c
>@@ -4377,22 +4377,6 @@ softnet_break:
> 	goto out;
> }
>
>-struct netdev_adjacent {
>-	struct net_device *dev;
>-
>-	/* upper master flag, there can only be one master device per list */
>-	bool master;
>-
>-	/* counter for the number of times this device was added to us */
>-	u16 ref_nr;
>-
>-	/* private field for the users */
>-	void *private;
>-
>-	struct list_head list;
>-	struct rcu_head rcu;
>-};
>-
> static struct netdev_adjacent *__netdev_find_adj_rcu(struct net_device *dev,
> 						     struct net_device *adj_dev,
> 						     struct list_head *adj_list)
>-- 
>1.8.2.1
>
>
>

Re: [PATCH net-next v3 5/10] bonding: create bond_first_slave_rcu()

[Ding Tianhong]

On 2013/11/11 20:59, Veaceslav Falico wrote:
> On Mon, Nov 11, 2013 at 08:36:41PM +0800, Ding Tianhong wrote:
>> The bond_first_slave_rcu() will be used to instead of bond_first_slave()
>> in rcu_read_lock().
>>
>> So move the struct netdev_adjacent to the netdevice.h and make the
>> bond_first_slave_rcu() could use the struct.
> 
> The whole point in netdev_adjacent functions was to hide it from the users
> who wanted to use it directly. See
> 
> http://www.spinics.net/lists/netdev/msg248026.html
> 
> for reference. Please try to avoid that.
> 
Hi, Veaceslav
following the point, I rebuild the bond_first_slave_rcu(),
if you have no comments, I will move it in the patch set.

Regards
Ding

+/* Caller must have rcu_read_lock */
+#define bond_first_slave_rcu(bond) \
+       netdev_lower_get_first_private_rcu(bond->dev)
+
 #define bond_is_first_slave(bond, pos) (pos == bond_first_slave(bond))
 #define bond_is_last_slave(bond, pos) (pos == bond_last_slave(bond))

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 15fa01c..abfcfad 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2869,6 +2869,7 @@ void *netdev_lower_get_next_private_rcu(struct net_device *dev,
             priv = netdev_lower_get_next_private_rcu(dev, &(iter)))

 void *netdev_adjacent_get_private(struct list_head *adj_list);
+void *netdev_lower_get_first_private_rcu(struct net_device *dev);
 struct net_device *netdev_master_upper_dev_get(struct net_device *dev);
 struct net_device *netdev_master_upper_dev_get_rcu(struct net_device *dev);
 int netdev_upper_dev_link(struct net_device *dev, struct net_device *upper_dev);
diff --git a/net/core/dev.c b/net/core/dev.c
index 8ffc52e..39bc202 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4570,6 +4570,27 @@ void *netdev_lower_get_next_private_rcu(struct net_device *dev,
 EXPORT_SYMBOL(netdev_lower_get_next_private_rcu);

 /**
+ * netdev_lower_get_first_private_rcu - Get the first ->private from the
+ *                                    lower neighbour list, RCU
+ *                                    variant
+ * @dev: device
+ *
+ * Gets the first netdev_adjacent->private from the dev's lower neighbour
+ * list. The caller must hold RCU read lock.
+ */
+void *netdev_lower_get_first_private_rcu(struct net_device *dev)
+{
+       struct netdev_adjacent *lower;
+
+       lower = list_first_or_null_rcu(&dev->adj_list.lower,
+                       struct netdev_adjacent, list);
+       if (lower)
+               return lower->private;
+       return NULL;
+}
+EXPORT_SYMBOL(netdev_lower_get_first_private_rcu);