RDMA/core: Introduce rdma_read_gid_attr_ndev_rcu() to check GID attribute

Introduce an API rdma_read_gid_attr_ndev_rcu() to return GID attribute
netdevice which is in UP state for accessing netdevice's fields such as
net namespace and ifindex.

This is useful for users who intent to access netdevice fields under rcu
lock.

Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

diff --git a/drivers/infiniband/core/cache.c b/drivers/infiniband/core/cache.c
index 0bee1f4b914e751d9893875665d0b588d7e3258d..8957d31d60ca29bbcc369d4726b3b906889598be 100644 (file)
--- a/drivers/infiniband/core/cache.c
+++ b/drivers/infiniband/core/cache.c
@@ -1252,6 +1252,39 @@ void rdma_hold_gid_attr(const struct ib_gid_attr *attr)
 }
 EXPORT_SYMBOL(rdma_hold_gid_attr);
 
+/**
+ * rdma_read_gid_attr_ndev_rcu - Read GID attribute netdevice
+ * which must be in UP state.
+ *
+ * @attr:Pointer to the GID attribute
+ *
+ * Returns pointer to netdevice if the netdevice was attached to GID and
+ * netdevice is in UP state. Caller must hold RCU lock as this API
+ * reads the netdev flags which can change while netdevice migrates to
+ * different net namespace. Returns ERR_PTR with error code otherwise.
+ *
+ */
+struct net_device *rdma_read_gid_attr_ndev_rcu(const struct ib_gid_attr *attr)
+{
+       struct ib_gid_table_entry *entry =
+                       container_of(attr, struct ib_gid_table_entry, attr);
+       struct ib_device *device = entry->attr.device;
+       struct net_device *ndev = ERR_PTR(-ENODEV);
+       u8 port_num = entry->attr.port_num;
+       struct ib_gid_table *table;
+       unsigned long flags;
+       bool valid;
+
+       table = rdma_gid_table(device, port_num);
+
+       read_lock_irqsave(&table->rwlock, flags);
+       valid = is_gid_entry_valid(table->data_vec[attr->index]);
+       if (valid && attr->ndev && (READ_ONCE(attr->ndev->flags) & IFF_UP))
+               ndev = attr->ndev;
+       read_unlock_irqrestore(&table->rwlock, flags);
+       return ndev;
+}
+
 static int config_non_roce_gid_cache(struct ib_device *device,
                                     u8 port, int gid_tbl_len)
 {

diff --git a/drivers/infiniband/core/core_priv.h b/drivers/infiniband/core/core_priv.h
index 4dfcf41d83c0840ead27ae0b5f3bcbea1139a428..33f50e1929e7def59ea7e7ca9195f0ad6960856e 100644 (file)
--- a/drivers/infiniband/core/core_priv.h
+++ b/drivers/infiniband/core/core_priv.h
@@ -346,4 +346,6 @@ void rdma_copy_src_l2_addr(struct rdma_dev_addr *dev_addr,
 struct sa_path_rec;
 int roce_resolve_route_from_path(struct sa_path_rec *rec,
                                 const struct ib_gid_attr *attr);
+
+struct net_device *rdma_read_gid_attr_ndev_rcu(const struct ib_gid_attr *attr);
 #endif /* _CORE_PRIV_H */