RDMA/core: Allow detaching gid attribute netdevice for RoCE

When there is active traffic through a GID, a QP/AH holds reference to
this GID entry. RoCE GID entry holds reference to its attached
netdevice. Due to this when netdevice is deleted by admin user, its
refcount is not dropped.

Therefore, while deleting RoCE GID, wait for all GID attribute's netdev
users to finish accessing netdev in rcu context.  Once all users done
accessing it, release the netdev refcount.

Signed-off-by: Huy Nguyen <huyn@mellanox.com>
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 a53c7713d77a1750c25175f356c408e75b92bab1..099d922ae7bd57b0570b17103c1e90a0cf1f1898 100644 (file)
--- a/drivers/infiniband/core/cache.c
+++ b/drivers/infiniband/core/cache.c
@@ -78,11 +78,22 @@ enum gid_table_entry_state {
        GID_TABLE_ENTRY_PENDING_DEL     = 3,
 };
 
+struct roce_gid_ndev_storage {
+       struct rcu_head rcu_head;
+       struct net_device *ndev;
+};
+
 struct ib_gid_table_entry {
        struct kref                     kref;
        struct work_struct              del_work;
        struct ib_gid_attr              attr;
        void                            *context;
+       /* Store the ndev pointer to release reference later on in
+        * call_rcu context because by that time gid_table_entry
+        * and attr might be already freed. So keep a copy of it.
+        * ndev_storage is freed by rcu callback.
+        */
+       struct roce_gid_ndev_storage    *ndev_storage;
        enum gid_table_entry_state      state;
 };
 
@@ -206,6 +217,20 @@ static void schedule_free_gid(struct kref *kref)
        queue_work(ib_wq, &entry->del_work);
 }
 
+static void put_gid_ndev(struct rcu_head *head)
+{
+       struct roce_gid_ndev_storage *storage =
+               container_of(head, struct roce_gid_ndev_storage, rcu_head);
+
+       WARN_ON(!storage->ndev);
+       /* At this point its safe to release netdev reference,
+        * as all callers working on gid_attr->ndev are done
+        * using this netdev.
+        */
+       dev_put(storage->ndev);
+       kfree(storage);
+}
+
 static void free_gid_entry_locked(struct ib_gid_table_entry *entry)
 {
        struct ib_device *device = entry->attr.device;
@@ -228,8 +253,8 @@ static void free_gid_entry_locked(struct ib_gid_table_entry *entry)
        /* Now this index is ready to be allocated */
        write_unlock_irq(&table->rwlock);
 
-       if (entry->attr.ndev)
-               dev_put(entry->attr.ndev);
+       if (entry->ndev_storage)
+               call_rcu(&entry->ndev_storage->rcu_head, put_gid_ndev);
        kfree(entry);
 }
 
@@ -266,14 +291,25 @@ static struct ib_gid_table_entry *
 alloc_gid_entry(const struct ib_gid_attr *attr)
 {
        struct ib_gid_table_entry *entry;
+       struct net_device *ndev;
 
        entry = kzalloc(sizeof(*entry), GFP_KERNEL);
        if (!entry)
                return NULL;
+
+       ndev = rcu_dereference_protected(attr->ndev, 1);
+       if (ndev) {
+               entry->ndev_storage = kzalloc(sizeof(*entry->ndev_storage),
+                                             GFP_KERNEL);
+               if (!entry->ndev_storage) {
+                       kfree(entry);
+                       return NULL;
+               }
+               dev_hold(ndev);
+               entry->ndev_storage->ndev = ndev;
+       }
        kref_init(&entry->kref);
        memcpy(&entry->attr, attr, sizeof(*attr));
-       if (entry->attr.ndev)
-               dev_hold(entry->attr.ndev);
        INIT_WORK(&entry->del_work, free_gid_work);
        entry->state = GID_TABLE_ENTRY_INVALID;
        return entry;
@@ -343,6 +379,7 @@ static int add_roce_gid(struct ib_gid_table_entry *entry)
 static void del_gid(struct ib_device *ib_dev, u8 port,
                    struct ib_gid_table *table, int ix)
 {
+       struct roce_gid_ndev_storage *ndev_storage;
        struct ib_gid_table_entry *entry;
 
        lockdep_assert_held(&table->lock);
@@ -360,6 +397,13 @@ static void del_gid(struct ib_device *ib_dev, u8 port,
                table->data_vec[ix] = NULL;
        write_unlock_irq(&table->rwlock);
 
+       ndev_storage = entry->ndev_storage;
+       if (ndev_storage) {
+               entry->ndev_storage = NULL;
+               rcu_assign_pointer(entry->attr.ndev, NULL);
+               call_rcu(&ndev_storage->rcu_head, put_gid_ndev);
+       }
+
        if (rdma_cap_roce_gid_table(ib_dev, port))
                ib_dev->ops.del_gid(&entry->attr, &entry->context);
 
@@ -1244,8 +1288,12 @@ struct net_device *rdma_read_gid_attr_ndev_rcu(const struct ib_gid_attr *attr)
 
        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;
+       if (valid) {
+               ndev = rcu_dereference(attr->ndev);
+               if (!ndev ||
+                   (ndev && ((READ_ONCE(ndev->flags) & IFF_UP) == 0)))
+                       ndev = ERR_PTR(-ENODEV);
+       }
        read_unlock_irqrestore(&table->rwlock, flags);
        return ndev;
 }
@@ -1281,10 +1329,12 @@ int rdma_read_gid_l2_fields(const struct ib_gid_attr *attr,
 {
        struct net_device *ndev;
 
-       ndev = attr->ndev;
-       if (!ndev)
-               return -EINVAL;
-
+       rcu_read_lock();
+       ndev = rcu_dereference(attr->ndev);
+       if (!ndev) {
+               rcu_read_unlock();
+               return -ENODEV;
+       }
        if (smac)
                ether_addr_copy(smac, ndev->dev_addr);
        if (vlan_id) {
@@ -1296,12 +1346,11 @@ int rdma_read_gid_l2_fields(const struct ib_gid_attr *attr,
                         * device is vlan device, consider vlan id of the
                         * the lower vlan device for this gid entry.
                         */
-                       rcu_read_lock();
                        netdev_walk_all_lower_dev_rcu(attr->ndev,
                                        get_lower_dev_vlan, vlan_id);
-                       rcu_read_unlock();
                }
        }
+       rcu_read_unlock();
        return 0;
 }
 EXPORT_SYMBOL(rdma_read_gid_l2_fields);

diff --git a/drivers/infiniband/core/sysfs.c b/drivers/infiniband/core/sysfs.c
index 7a599c5e455fa9ee44337e3fe1fa264268e11a75..8c7adc27aeeae254906110dbabc68a49c3e1ad22 100644 (file)
--- a/drivers/infiniband/core/sysfs.c
+++ b/drivers/infiniband/core/sysfs.c
@@ -349,10 +349,15 @@ static struct attribute *port_default_attrs[] = {
 
 static size_t print_ndev(const struct ib_gid_attr *gid_attr, char *buf)
 {
-       if (!gid_attr->ndev)
-               return -EINVAL;
-
-       return sprintf(buf, "%s\n", gid_attr->ndev->name);
+       struct net_device *ndev;
+       size_t ret = -EINVAL;
+
+       rcu_read_lock();
+       ndev = rcu_dereference(gid_attr->ndev);
+       if (ndev)
+               ret = sprintf(buf, "%s\n", ndev->name);
+       rcu_read_unlock();
+       return ret;
 }
 
 static size_t print_gid_type(const struct ib_gid_attr *gid_attr, char *buf)

diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 4312899231caf7f6f82ae33551dd54088701b557..8f8965f8ffdb4938068f8cd88ae0a5602fbacc0e 100644 (file)
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -124,7 +124,7 @@ enum ib_gid_type {
 
 #define ROCE_V2_UDP_DPORT      4791
 struct ib_gid_attr {
-       struct net_device       *ndev;
+       struct net_device __rcu *ndev;
        struct ib_device        *device;
        union ib_gid            gid;
        enum ib_gid_type        gid_type;