mirror of https://gitee.com/openkylin/linux.git
772 lines
21 KiB
C
772 lines
21 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Copyright (c) 2017 Covalent IO, Inc. http://covalent.io
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*/
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/* Devmaps primary use is as a backend map for XDP BPF helper call
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* bpf_redirect_map(). Because XDP is mostly concerned with performance we
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* spent some effort to ensure the datapath with redirect maps does not use
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* any locking. This is a quick note on the details.
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*
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* We have three possible paths to get into the devmap control plane bpf
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* syscalls, bpf programs, and driver side xmit/flush operations. A bpf syscall
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* will invoke an update, delete, or lookup operation. To ensure updates and
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* deletes appear atomic from the datapath side xchg() is used to modify the
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* netdev_map array. Then because the datapath does a lookup into the netdev_map
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* array (read-only) from an RCU critical section we use call_rcu() to wait for
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* an rcu grace period before free'ing the old data structures. This ensures the
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* datapath always has a valid copy. However, the datapath does a "flush"
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* operation that pushes any pending packets in the driver outside the RCU
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* critical section. Each bpf_dtab_netdev tracks these pending operations using
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* a per-cpu flush list. The bpf_dtab_netdev object will not be destroyed until
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* this list is empty, indicating outstanding flush operations have completed.
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*
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* BPF syscalls may race with BPF program calls on any of the update, delete
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* or lookup operations. As noted above the xchg() operation also keep the
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* netdev_map consistent in this case. From the devmap side BPF programs
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* calling into these operations are the same as multiple user space threads
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* making system calls.
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*
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* Finally, any of the above may race with a netdev_unregister notifier. The
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* unregister notifier must search for net devices in the map structure that
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* contain a reference to the net device and remove them. This is a two step
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* process (a) dereference the bpf_dtab_netdev object in netdev_map and (b)
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* check to see if the ifindex is the same as the net_device being removed.
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* When removing the dev a cmpxchg() is used to ensure the correct dev is
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* removed, in the case of a concurrent update or delete operation it is
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* possible that the initially referenced dev is no longer in the map. As the
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* notifier hook walks the map we know that new dev references can not be
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* added by the user because core infrastructure ensures dev_get_by_index()
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* calls will fail at this point.
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*
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* The devmap_hash type is a map type which interprets keys as ifindexes and
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* indexes these using a hashmap. This allows maps that use ifindex as key to be
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* densely packed instead of having holes in the lookup array for unused
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* ifindexes. The setup and packet enqueue/send code is shared between the two
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* types of devmap; only the lookup and insertion is different.
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*/
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#include <linux/bpf.h>
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#include <net/xdp.h>
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#include <linux/filter.h>
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#include <trace/events/xdp.h>
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#define DEV_CREATE_FLAG_MASK \
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(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
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#define DEV_MAP_BULK_SIZE 16
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struct bpf_dtab_netdev;
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struct xdp_bulk_queue {
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struct xdp_frame *q[DEV_MAP_BULK_SIZE];
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struct list_head flush_node;
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struct net_device *dev_rx;
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struct bpf_dtab_netdev *obj;
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unsigned int count;
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};
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struct bpf_dtab_netdev {
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struct net_device *dev; /* must be first member, due to tracepoint */
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struct hlist_node index_hlist;
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struct bpf_dtab *dtab;
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struct xdp_bulk_queue __percpu *bulkq;
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struct rcu_head rcu;
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unsigned int idx; /* keep track of map index for tracepoint */
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};
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struct bpf_dtab {
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struct bpf_map map;
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struct bpf_dtab_netdev **netdev_map;
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struct list_head __percpu *flush_list;
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struct list_head list;
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/* these are only used for DEVMAP_HASH type maps */
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struct hlist_head *dev_index_head;
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spinlock_t index_lock;
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unsigned int items;
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u32 n_buckets;
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};
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static DEFINE_SPINLOCK(dev_map_lock);
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static LIST_HEAD(dev_map_list);
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static struct hlist_head *dev_map_create_hash(unsigned int entries)
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{
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int i;
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struct hlist_head *hash;
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hash = kmalloc_array(entries, sizeof(*hash), GFP_KERNEL);
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if (hash != NULL)
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for (i = 0; i < entries; i++)
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INIT_HLIST_HEAD(&hash[i]);
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return hash;
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}
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static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
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{
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int err, cpu;
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u64 cost;
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/* check sanity of attributes */
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if (attr->max_entries == 0 || attr->key_size != 4 ||
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attr->value_size != 4 || attr->map_flags & ~DEV_CREATE_FLAG_MASK)
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return -EINVAL;
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/* Lookup returns a pointer straight to dev->ifindex, so make sure the
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* verifier prevents writes from the BPF side
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*/
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attr->map_flags |= BPF_F_RDONLY_PROG;
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bpf_map_init_from_attr(&dtab->map, attr);
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/* make sure page count doesn't overflow */
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cost = (u64) dtab->map.max_entries * sizeof(struct bpf_dtab_netdev *);
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cost += sizeof(struct list_head) * num_possible_cpus();
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if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
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dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
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if (!dtab->n_buckets) /* Overflow check */
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return -EINVAL;
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cost += sizeof(struct hlist_head) * dtab->n_buckets;
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}
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/* if map size is larger than memlock limit, reject it */
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err = bpf_map_charge_init(&dtab->map.memory, cost);
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if (err)
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return -EINVAL;
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dtab->flush_list = alloc_percpu(struct list_head);
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if (!dtab->flush_list)
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goto free_charge;
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for_each_possible_cpu(cpu)
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INIT_LIST_HEAD(per_cpu_ptr(dtab->flush_list, cpu));
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dtab->netdev_map = bpf_map_area_alloc(dtab->map.max_entries *
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sizeof(struct bpf_dtab_netdev *),
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dtab->map.numa_node);
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if (!dtab->netdev_map)
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goto free_percpu;
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if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
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dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets);
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if (!dtab->dev_index_head)
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goto free_map_area;
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spin_lock_init(&dtab->index_lock);
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}
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return 0;
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free_map_area:
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bpf_map_area_free(dtab->netdev_map);
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free_percpu:
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free_percpu(dtab->flush_list);
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free_charge:
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bpf_map_charge_finish(&dtab->map.memory);
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return -ENOMEM;
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}
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static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
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{
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struct bpf_dtab *dtab;
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int err;
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if (!capable(CAP_NET_ADMIN))
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return ERR_PTR(-EPERM);
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dtab = kzalloc(sizeof(*dtab), GFP_USER);
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if (!dtab)
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return ERR_PTR(-ENOMEM);
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err = dev_map_init_map(dtab, attr);
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if (err) {
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kfree(dtab);
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return ERR_PTR(err);
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}
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spin_lock(&dev_map_lock);
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list_add_tail_rcu(&dtab->list, &dev_map_list);
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spin_unlock(&dev_map_lock);
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return &dtab->map;
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}
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static void dev_map_free(struct bpf_map *map)
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{
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struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
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int i, cpu;
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/* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
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* so the programs (can be more than one that used this map) were
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* disconnected from events. Wait for outstanding critical sections in
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* these programs to complete. The rcu critical section only guarantees
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* no further reads against netdev_map. It does __not__ ensure pending
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* flush operations (if any) are complete.
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*/
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spin_lock(&dev_map_lock);
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list_del_rcu(&dtab->list);
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spin_unlock(&dev_map_lock);
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bpf_clear_redirect_map(map);
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synchronize_rcu();
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/* Make sure prior __dev_map_entry_free() have completed. */
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rcu_barrier();
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/* To ensure all pending flush operations have completed wait for flush
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* list to empty on _all_ cpus.
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* Because the above synchronize_rcu() ensures the map is disconnected
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* from the program we can assume no new items will be added.
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*/
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for_each_online_cpu(cpu) {
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struct list_head *flush_list = per_cpu_ptr(dtab->flush_list, cpu);
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while (!list_empty(flush_list))
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cond_resched();
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}
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for (i = 0; i < dtab->map.max_entries; i++) {
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struct bpf_dtab_netdev *dev;
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dev = dtab->netdev_map[i];
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if (!dev)
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continue;
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free_percpu(dev->bulkq);
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dev_put(dev->dev);
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kfree(dev);
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}
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free_percpu(dtab->flush_list);
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bpf_map_area_free(dtab->netdev_map);
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kfree(dtab->dev_index_head);
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kfree(dtab);
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}
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static int dev_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
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{
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struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
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u32 index = key ? *(u32 *)key : U32_MAX;
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u32 *next = next_key;
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if (index >= dtab->map.max_entries) {
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*next = 0;
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return 0;
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}
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if (index == dtab->map.max_entries - 1)
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return -ENOENT;
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*next = index + 1;
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return 0;
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}
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static inline struct hlist_head *dev_map_index_hash(struct bpf_dtab *dtab,
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int idx)
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{
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return &dtab->dev_index_head[idx & (dtab->n_buckets - 1)];
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}
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struct bpf_dtab_netdev *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key)
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{
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struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
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struct hlist_head *head = dev_map_index_hash(dtab, key);
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struct bpf_dtab_netdev *dev;
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hlist_for_each_entry_rcu(dev, head, index_hlist)
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if (dev->idx == key)
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return dev;
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return NULL;
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}
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static int dev_map_hash_get_next_key(struct bpf_map *map, void *key,
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void *next_key)
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{
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struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
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u32 idx, *next = next_key;
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struct bpf_dtab_netdev *dev, *next_dev;
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struct hlist_head *head;
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int i = 0;
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if (!key)
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goto find_first;
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idx = *(u32 *)key;
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dev = __dev_map_hash_lookup_elem(map, idx);
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if (!dev)
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goto find_first;
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next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&dev->index_hlist)),
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struct bpf_dtab_netdev, index_hlist);
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if (next_dev) {
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*next = next_dev->idx;
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return 0;
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}
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i = idx & (dtab->n_buckets - 1);
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i++;
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find_first:
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for (; i < dtab->n_buckets; i++) {
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head = dev_map_index_hash(dtab, i);
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next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
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struct bpf_dtab_netdev,
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index_hlist);
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if (next_dev) {
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*next = next_dev->idx;
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return 0;
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}
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}
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return -ENOENT;
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}
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static int bq_xmit_all(struct xdp_bulk_queue *bq, u32 flags,
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bool in_napi_ctx)
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{
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struct bpf_dtab_netdev *obj = bq->obj;
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struct net_device *dev = obj->dev;
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int sent = 0, drops = 0, err = 0;
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int i;
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if (unlikely(!bq->count))
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return 0;
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for (i = 0; i < bq->count; i++) {
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struct xdp_frame *xdpf = bq->q[i];
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prefetch(xdpf);
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}
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sent = dev->netdev_ops->ndo_xdp_xmit(dev, bq->count, bq->q, flags);
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if (sent < 0) {
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err = sent;
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sent = 0;
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goto error;
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}
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drops = bq->count - sent;
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out:
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bq->count = 0;
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trace_xdp_devmap_xmit(&obj->dtab->map, obj->idx,
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sent, drops, bq->dev_rx, dev, err);
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bq->dev_rx = NULL;
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__list_del_clearprev(&bq->flush_node);
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return 0;
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error:
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/* If ndo_xdp_xmit fails with an errno, no frames have been
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* xmit'ed and it's our responsibility to them free all.
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*/
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for (i = 0; i < bq->count; i++) {
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struct xdp_frame *xdpf = bq->q[i];
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/* RX path under NAPI protection, can return frames faster */
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if (likely(in_napi_ctx))
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xdp_return_frame_rx_napi(xdpf);
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else
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xdp_return_frame(xdpf);
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drops++;
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}
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goto out;
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}
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/* __dev_map_flush is called from xdp_do_flush_map() which _must_ be signaled
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* from the driver before returning from its napi->poll() routine. The poll()
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* routine is called either from busy_poll context or net_rx_action signaled
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* from NET_RX_SOFTIRQ. Either way the poll routine must complete before the
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* net device can be torn down. On devmap tear down we ensure the flush list
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* is empty before completing to ensure all flush operations have completed.
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*/
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void __dev_map_flush(struct bpf_map *map)
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{
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struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
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struct list_head *flush_list = this_cpu_ptr(dtab->flush_list);
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struct xdp_bulk_queue *bq, *tmp;
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rcu_read_lock();
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list_for_each_entry_safe(bq, tmp, flush_list, flush_node)
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bq_xmit_all(bq, XDP_XMIT_FLUSH, true);
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rcu_read_unlock();
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}
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/* rcu_read_lock (from syscall and BPF contexts) ensures that if a delete and/or
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* update happens in parallel here a dev_put wont happen until after reading the
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* ifindex.
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*/
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struct bpf_dtab_netdev *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
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{
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struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
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struct bpf_dtab_netdev *obj;
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if (key >= map->max_entries)
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return NULL;
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obj = READ_ONCE(dtab->netdev_map[key]);
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return obj;
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}
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/* Runs under RCU-read-side, plus in softirq under NAPI protection.
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* Thus, safe percpu variable access.
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*/
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static int bq_enqueue(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf,
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struct net_device *dev_rx)
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{
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struct list_head *flush_list = this_cpu_ptr(obj->dtab->flush_list);
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struct xdp_bulk_queue *bq = this_cpu_ptr(obj->bulkq);
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if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
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bq_xmit_all(bq, 0, true);
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/* Ingress dev_rx will be the same for all xdp_frame's in
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* bulk_queue, because bq stored per-CPU and must be flushed
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* from net_device drivers NAPI func end.
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*/
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if (!bq->dev_rx)
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bq->dev_rx = dev_rx;
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bq->q[bq->count++] = xdpf;
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if (!bq->flush_node.prev)
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list_add(&bq->flush_node, flush_list);
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return 0;
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}
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int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
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struct net_device *dev_rx)
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{
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struct net_device *dev = dst->dev;
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struct xdp_frame *xdpf;
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int err;
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if (!dev->netdev_ops->ndo_xdp_xmit)
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return -EOPNOTSUPP;
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err = xdp_ok_fwd_dev(dev, xdp->data_end - xdp->data);
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if (unlikely(err))
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return err;
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xdpf = convert_to_xdp_frame(xdp);
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if (unlikely(!xdpf))
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return -EOVERFLOW;
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return bq_enqueue(dst, xdpf, dev_rx);
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}
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int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
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struct bpf_prog *xdp_prog)
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{
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int err;
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err = xdp_ok_fwd_dev(dst->dev, skb->len);
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if (unlikely(err))
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return err;
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skb->dev = dst->dev;
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generic_xdp_tx(skb, xdp_prog);
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return 0;
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}
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static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
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{
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struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
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struct net_device *dev = obj ? obj->dev : NULL;
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return dev ? &dev->ifindex : NULL;
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}
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static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key)
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{
|
|
struct bpf_dtab_netdev *obj = __dev_map_hash_lookup_elem(map,
|
|
*(u32 *)key);
|
|
struct net_device *dev = obj ? obj->dev : NULL;
|
|
|
|
return dev ? &dev->ifindex : NULL;
|
|
}
|
|
|
|
static void dev_map_flush_old(struct bpf_dtab_netdev *dev)
|
|
{
|
|
if (dev->dev->netdev_ops->ndo_xdp_xmit) {
|
|
struct xdp_bulk_queue *bq;
|
|
int cpu;
|
|
|
|
rcu_read_lock();
|
|
for_each_online_cpu(cpu) {
|
|
bq = per_cpu_ptr(dev->bulkq, cpu);
|
|
bq_xmit_all(bq, XDP_XMIT_FLUSH, false);
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
}
|
|
|
|
static void __dev_map_entry_free(struct rcu_head *rcu)
|
|
{
|
|
struct bpf_dtab_netdev *dev;
|
|
|
|
dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
|
|
dev_map_flush_old(dev);
|
|
free_percpu(dev->bulkq);
|
|
dev_put(dev->dev);
|
|
kfree(dev);
|
|
}
|
|
|
|
static int dev_map_delete_elem(struct bpf_map *map, void *key)
|
|
{
|
|
struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
|
|
struct bpf_dtab_netdev *old_dev;
|
|
int k = *(u32 *)key;
|
|
|
|
if (k >= map->max_entries)
|
|
return -EINVAL;
|
|
|
|
/* Use call_rcu() here to ensure any rcu critical sections have
|
|
* completed, but this does not guarantee a flush has happened
|
|
* yet. Because driver side rcu_read_lock/unlock only protects the
|
|
* running XDP program. However, for pending flush operations the
|
|
* dev and ctx are stored in another per cpu map. And additionally,
|
|
* the driver tear down ensures all soft irqs are complete before
|
|
* removing the net device in the case of dev_put equals zero.
|
|
*/
|
|
old_dev = xchg(&dtab->netdev_map[k], NULL);
|
|
if (old_dev)
|
|
call_rcu(&old_dev->rcu, __dev_map_entry_free);
|
|
return 0;
|
|
}
|
|
|
|
static int dev_map_hash_delete_elem(struct bpf_map *map, void *key)
|
|
{
|
|
struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
|
|
struct bpf_dtab_netdev *old_dev;
|
|
int k = *(u32 *)key;
|
|
unsigned long flags;
|
|
int ret = -ENOENT;
|
|
|
|
spin_lock_irqsave(&dtab->index_lock, flags);
|
|
|
|
old_dev = __dev_map_hash_lookup_elem(map, k);
|
|
if (old_dev) {
|
|
dtab->items--;
|
|
hlist_del_init_rcu(&old_dev->index_hlist);
|
|
call_rcu(&old_dev->rcu, __dev_map_entry_free);
|
|
ret = 0;
|
|
}
|
|
spin_unlock_irqrestore(&dtab->index_lock, flags);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
|
|
struct bpf_dtab *dtab,
|
|
u32 ifindex,
|
|
unsigned int idx)
|
|
{
|
|
gfp_t gfp = GFP_ATOMIC | __GFP_NOWARN;
|
|
struct bpf_dtab_netdev *dev;
|
|
struct xdp_bulk_queue *bq;
|
|
int cpu;
|
|
|
|
dev = kmalloc_node(sizeof(*dev), gfp, dtab->map.numa_node);
|
|
if (!dev)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
dev->bulkq = __alloc_percpu_gfp(sizeof(*dev->bulkq),
|
|
sizeof(void *), gfp);
|
|
if (!dev->bulkq) {
|
|
kfree(dev);
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
bq = per_cpu_ptr(dev->bulkq, cpu);
|
|
bq->obj = dev;
|
|
}
|
|
|
|
dev->dev = dev_get_by_index(net, ifindex);
|
|
if (!dev->dev) {
|
|
free_percpu(dev->bulkq);
|
|
kfree(dev);
|
|
return ERR_PTR(-EINVAL);
|
|
}
|
|
|
|
dev->idx = idx;
|
|
dev->dtab = dtab;
|
|
|
|
return dev;
|
|
}
|
|
|
|
static int __dev_map_update_elem(struct net *net, struct bpf_map *map,
|
|
void *key, void *value, u64 map_flags)
|
|
{
|
|
struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
|
|
struct bpf_dtab_netdev *dev, *old_dev;
|
|
u32 ifindex = *(u32 *)value;
|
|
u32 i = *(u32 *)key;
|
|
|
|
if (unlikely(map_flags > BPF_EXIST))
|
|
return -EINVAL;
|
|
if (unlikely(i >= dtab->map.max_entries))
|
|
return -E2BIG;
|
|
if (unlikely(map_flags == BPF_NOEXIST))
|
|
return -EEXIST;
|
|
|
|
if (!ifindex) {
|
|
dev = NULL;
|
|
} else {
|
|
dev = __dev_map_alloc_node(net, dtab, ifindex, i);
|
|
if (IS_ERR(dev))
|
|
return PTR_ERR(dev);
|
|
}
|
|
|
|
/* Use call_rcu() here to ensure rcu critical sections have completed
|
|
* Remembering the driver side flush operation will happen before the
|
|
* net device is removed.
|
|
*/
|
|
old_dev = xchg(&dtab->netdev_map[i], dev);
|
|
if (old_dev)
|
|
call_rcu(&old_dev->rcu, __dev_map_entry_free);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int dev_map_update_elem(struct bpf_map *map, void *key, void *value,
|
|
u64 map_flags)
|
|
{
|
|
return __dev_map_update_elem(current->nsproxy->net_ns,
|
|
map, key, value, map_flags);
|
|
}
|
|
|
|
static int __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
|
|
void *key, void *value, u64 map_flags)
|
|
{
|
|
struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
|
|
struct bpf_dtab_netdev *dev, *old_dev;
|
|
u32 ifindex = *(u32 *)value;
|
|
u32 idx = *(u32 *)key;
|
|
unsigned long flags;
|
|
int err = -EEXIST;
|
|
|
|
if (unlikely(map_flags > BPF_EXIST || !ifindex))
|
|
return -EINVAL;
|
|
|
|
spin_lock_irqsave(&dtab->index_lock, flags);
|
|
|
|
old_dev = __dev_map_hash_lookup_elem(map, idx);
|
|
if (old_dev && (map_flags & BPF_NOEXIST))
|
|
goto out_err;
|
|
|
|
dev = __dev_map_alloc_node(net, dtab, ifindex, idx);
|
|
if (IS_ERR(dev)) {
|
|
err = PTR_ERR(dev);
|
|
goto out_err;
|
|
}
|
|
|
|
if (old_dev) {
|
|
hlist_del_rcu(&old_dev->index_hlist);
|
|
} else {
|
|
if (dtab->items >= dtab->map.max_entries) {
|
|
spin_unlock_irqrestore(&dtab->index_lock, flags);
|
|
call_rcu(&dev->rcu, __dev_map_entry_free);
|
|
return -E2BIG;
|
|
}
|
|
dtab->items++;
|
|
}
|
|
|
|
hlist_add_head_rcu(&dev->index_hlist,
|
|
dev_map_index_hash(dtab, idx));
|
|
spin_unlock_irqrestore(&dtab->index_lock, flags);
|
|
|
|
if (old_dev)
|
|
call_rcu(&old_dev->rcu, __dev_map_entry_free);
|
|
|
|
return 0;
|
|
|
|
out_err:
|
|
spin_unlock_irqrestore(&dtab->index_lock, flags);
|
|
return err;
|
|
}
|
|
|
|
static int dev_map_hash_update_elem(struct bpf_map *map, void *key, void *value,
|
|
u64 map_flags)
|
|
{
|
|
return __dev_map_hash_update_elem(current->nsproxy->net_ns,
|
|
map, key, value, map_flags);
|
|
}
|
|
|
|
const struct bpf_map_ops dev_map_ops = {
|
|
.map_alloc = dev_map_alloc,
|
|
.map_free = dev_map_free,
|
|
.map_get_next_key = dev_map_get_next_key,
|
|
.map_lookup_elem = dev_map_lookup_elem,
|
|
.map_update_elem = dev_map_update_elem,
|
|
.map_delete_elem = dev_map_delete_elem,
|
|
.map_check_btf = map_check_no_btf,
|
|
};
|
|
|
|
const struct bpf_map_ops dev_map_hash_ops = {
|
|
.map_alloc = dev_map_alloc,
|
|
.map_free = dev_map_free,
|
|
.map_get_next_key = dev_map_hash_get_next_key,
|
|
.map_lookup_elem = dev_map_hash_lookup_elem,
|
|
.map_update_elem = dev_map_hash_update_elem,
|
|
.map_delete_elem = dev_map_hash_delete_elem,
|
|
.map_check_btf = map_check_no_btf,
|
|
};
|
|
|
|
static int dev_map_notification(struct notifier_block *notifier,
|
|
ulong event, void *ptr)
|
|
{
|
|
struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
|
|
struct bpf_dtab *dtab;
|
|
int i;
|
|
|
|
switch (event) {
|
|
case NETDEV_UNREGISTER:
|
|
/* This rcu_read_lock/unlock pair is needed because
|
|
* dev_map_list is an RCU list AND to ensure a delete
|
|
* operation does not free a netdev_map entry while we
|
|
* are comparing it against the netdev being unregistered.
|
|
*/
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(dtab, &dev_map_list, list) {
|
|
for (i = 0; i < dtab->map.max_entries; i++) {
|
|
struct bpf_dtab_netdev *dev, *odev;
|
|
|
|
dev = READ_ONCE(dtab->netdev_map[i]);
|
|
if (!dev || netdev != dev->dev)
|
|
continue;
|
|
odev = cmpxchg(&dtab->netdev_map[i], dev, NULL);
|
|
if (dev == odev)
|
|
call_rcu(&dev->rcu,
|
|
__dev_map_entry_free);
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
static struct notifier_block dev_map_notifier = {
|
|
.notifier_call = dev_map_notification,
|
|
};
|
|
|
|
static int __init dev_map_init(void)
|
|
{
|
|
/* Assure tracepoint shadow struct _bpf_dtab_netdev is in sync */
|
|
BUILD_BUG_ON(offsetof(struct bpf_dtab_netdev, dev) !=
|
|
offsetof(struct _bpf_dtab_netdev, dev));
|
|
register_netdevice_notifier(&dev_map_notifier);
|
|
return 0;
|
|
}
|
|
|
|
subsys_initcall(dev_map_init);
|