swh:1:snp:3c665ee4f67729f27f2e40193ab88e7298cf0fef
Tip revision: 09162bc32c880a791c6c0668ce0745cf7958f576 authored by Linus Torvalds on 16 November 2020, 00:44:31 UTC
Linux 5.10-rc4
Linux 5.10-rc4
Tip revision: 09162bc
devmap.c
// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2017 Covalent IO, Inc. http://covalent.io
*/
/* Devmaps primary use is as a backend map for XDP BPF helper call
* bpf_redirect_map(). Because XDP is mostly concerned with performance we
* spent some effort to ensure the datapath with redirect maps does not use
* any locking. This is a quick note on the details.
*
* We have three possible paths to get into the devmap control plane bpf
* syscalls, bpf programs, and driver side xmit/flush operations. A bpf syscall
* will invoke an update, delete, or lookup operation. To ensure updates and
* deletes appear atomic from the datapath side xchg() is used to modify the
* netdev_map array. Then because the datapath does a lookup into the netdev_map
* array (read-only) from an RCU critical section we use call_rcu() to wait for
* an rcu grace period before free'ing the old data structures. This ensures the
* datapath always has a valid copy. However, the datapath does a "flush"
* operation that pushes any pending packets in the driver outside the RCU
* critical section. Each bpf_dtab_netdev tracks these pending operations using
* a per-cpu flush list. The bpf_dtab_netdev object will not be destroyed until
* this list is empty, indicating outstanding flush operations have completed.
*
* BPF syscalls may race with BPF program calls on any of the update, delete
* or lookup operations. As noted above the xchg() operation also keep the
* netdev_map consistent in this case. From the devmap side BPF programs
* calling into these operations are the same as multiple user space threads
* making system calls.
*
* Finally, any of the above may race with a netdev_unregister notifier. The
* unregister notifier must search for net devices in the map structure that
* contain a reference to the net device and remove them. This is a two step
* process (a) dereference the bpf_dtab_netdev object in netdev_map and (b)
* check to see if the ifindex is the same as the net_device being removed.
* When removing the dev a cmpxchg() is used to ensure the correct dev is
* removed, in the case of a concurrent update or delete operation it is
* possible that the initially referenced dev is no longer in the map. As the
* notifier hook walks the map we know that new dev references can not be
* added by the user because core infrastructure ensures dev_get_by_index()
* calls will fail at this point.
*
* The devmap_hash type is a map type which interprets keys as ifindexes and
* indexes these using a hashmap. This allows maps that use ifindex as key to be
* densely packed instead of having holes in the lookup array for unused
* ifindexes. The setup and packet enqueue/send code is shared between the two
* types of devmap; only the lookup and insertion is different.
*/
#include <linux/bpf.h>
#include <net/xdp.h>
#include <linux/filter.h>
#include <trace/events/xdp.h>
#define DEV_CREATE_FLAG_MASK \
(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
struct xdp_dev_bulk_queue {
struct xdp_frame *q[DEV_MAP_BULK_SIZE];
struct list_head flush_node;
struct net_device *dev;
struct net_device *dev_rx;
unsigned int count;
};
struct bpf_dtab_netdev {
struct net_device *dev; /* must be first member, due to tracepoint */
struct hlist_node index_hlist;
struct bpf_dtab *dtab;
struct bpf_prog *xdp_prog;
struct rcu_head rcu;
unsigned int idx;
struct bpf_devmap_val val;
};
struct bpf_dtab {
struct bpf_map map;
struct bpf_dtab_netdev **netdev_map; /* DEVMAP type only */
struct list_head list;
/* these are only used for DEVMAP_HASH type maps */
struct hlist_head *dev_index_head;
spinlock_t index_lock;
unsigned int items;
u32 n_buckets;
};
static DEFINE_PER_CPU(struct list_head, dev_flush_list);
static DEFINE_SPINLOCK(dev_map_lock);
static LIST_HEAD(dev_map_list);
static struct hlist_head *dev_map_create_hash(unsigned int entries,
int numa_node)
{
int i;
struct hlist_head *hash;
hash = bpf_map_area_alloc(entries * sizeof(*hash), numa_node);
if (hash != NULL)
for (i = 0; i < entries; i++)
INIT_HLIST_HEAD(&hash[i]);
return hash;
}
static inline struct hlist_head *dev_map_index_hash(struct bpf_dtab *dtab,
int idx)
{
return &dtab->dev_index_head[idx & (dtab->n_buckets - 1)];
}
static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
{
u32 valsize = attr->value_size;
u64 cost = 0;
int err;
/* check sanity of attributes. 2 value sizes supported:
* 4 bytes: ifindex
* 8 bytes: ifindex + prog fd
*/
if (attr->max_entries == 0 || attr->key_size != 4 ||
(valsize != offsetofend(struct bpf_devmap_val, ifindex) &&
valsize != offsetofend(struct bpf_devmap_val, bpf_prog.fd)) ||
attr->map_flags & ~DEV_CREATE_FLAG_MASK)
return -EINVAL;
/* Lookup returns a pointer straight to dev->ifindex, so make sure the
* verifier prevents writes from the BPF side
*/
attr->map_flags |= BPF_F_RDONLY_PROG;
bpf_map_init_from_attr(&dtab->map, attr);
if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
if (!dtab->n_buckets) /* Overflow check */
return -EINVAL;
cost += (u64) sizeof(struct hlist_head) * dtab->n_buckets;
} else {
cost += (u64) dtab->map.max_entries * sizeof(struct bpf_dtab_netdev *);
}
/* if map size is larger than memlock limit, reject it */
err = bpf_map_charge_init(&dtab->map.memory, cost);
if (err)
return -EINVAL;
if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets,
dtab->map.numa_node);
if (!dtab->dev_index_head)
goto free_charge;
spin_lock_init(&dtab->index_lock);
} else {
dtab->netdev_map = bpf_map_area_alloc(dtab->map.max_entries *
sizeof(struct bpf_dtab_netdev *),
dtab->map.numa_node);
if (!dtab->netdev_map)
goto free_charge;
}
return 0;
free_charge:
bpf_map_charge_finish(&dtab->map.memory);
return -ENOMEM;
}
static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
{
struct bpf_dtab *dtab;
int err;
if (!capable(CAP_NET_ADMIN))
return ERR_PTR(-EPERM);
dtab = kzalloc(sizeof(*dtab), GFP_USER);
if (!dtab)
return ERR_PTR(-ENOMEM);
err = dev_map_init_map(dtab, attr);
if (err) {
kfree(dtab);
return ERR_PTR(err);
}
spin_lock(&dev_map_lock);
list_add_tail_rcu(&dtab->list, &dev_map_list);
spin_unlock(&dev_map_lock);
return &dtab->map;
}
static void dev_map_free(struct bpf_map *map)
{
struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
int i;
/* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
* so the programs (can be more than one that used this map) were
* disconnected from events. The following synchronize_rcu() guarantees
* both rcu read critical sections complete and waits for
* preempt-disable regions (NAPI being the relevant context here) so we
* are certain there will be no further reads against the netdev_map and
* all flush operations are complete. Flush operations can only be done
* from NAPI context for this reason.
*/
spin_lock(&dev_map_lock);
list_del_rcu(&dtab->list);
spin_unlock(&dev_map_lock);
bpf_clear_redirect_map(map);
synchronize_rcu();
/* Make sure prior __dev_map_entry_free() have completed. */
rcu_barrier();
if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
for (i = 0; i < dtab->n_buckets; i++) {
struct bpf_dtab_netdev *dev;
struct hlist_head *head;
struct hlist_node *next;
head = dev_map_index_hash(dtab, i);
hlist_for_each_entry_safe(dev, next, head, index_hlist) {
hlist_del_rcu(&dev->index_hlist);
if (dev->xdp_prog)
bpf_prog_put(dev->xdp_prog);
dev_put(dev->dev);
kfree(dev);
}
}
bpf_map_area_free(dtab->dev_index_head);
} else {
for (i = 0; i < dtab->map.max_entries; i++) {
struct bpf_dtab_netdev *dev;
dev = dtab->netdev_map[i];
if (!dev)
continue;
if (dev->xdp_prog)
bpf_prog_put(dev->xdp_prog);
dev_put(dev->dev);
kfree(dev);
}
bpf_map_area_free(dtab->netdev_map);
}
kfree(dtab);
}
static int dev_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
{
struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
u32 index = key ? *(u32 *)key : U32_MAX;
u32 *next = next_key;
if (index >= dtab->map.max_entries) {
*next = 0;
return 0;
}
if (index == dtab->map.max_entries - 1)
return -ENOENT;
*next = index + 1;
return 0;
}
struct bpf_dtab_netdev *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key)
{
struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
struct hlist_head *head = dev_map_index_hash(dtab, key);
struct bpf_dtab_netdev *dev;
hlist_for_each_entry_rcu(dev, head, index_hlist,
lockdep_is_held(&dtab->index_lock))
if (dev->idx == key)
return dev;
return NULL;
}
static int dev_map_hash_get_next_key(struct bpf_map *map, void *key,
void *next_key)
{
struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
u32 idx, *next = next_key;
struct bpf_dtab_netdev *dev, *next_dev;
struct hlist_head *head;
int i = 0;
if (!key)
goto find_first;
idx = *(u32 *)key;
dev = __dev_map_hash_lookup_elem(map, idx);
if (!dev)
goto find_first;
next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&dev->index_hlist)),
struct bpf_dtab_netdev, index_hlist);
if (next_dev) {
*next = next_dev->idx;
return 0;
}
i = idx & (dtab->n_buckets - 1);
i++;
find_first:
for (; i < dtab->n_buckets; i++) {
head = dev_map_index_hash(dtab, i);
next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
struct bpf_dtab_netdev,
index_hlist);
if (next_dev) {
*next = next_dev->idx;
return 0;
}
}
return -ENOENT;
}
bool dev_map_can_have_prog(struct bpf_map *map)
{
if ((map->map_type == BPF_MAP_TYPE_DEVMAP ||
map->map_type == BPF_MAP_TYPE_DEVMAP_HASH) &&
map->value_size != offsetofend(struct bpf_devmap_val, ifindex))
return true;
return false;
}
static void bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
{
struct net_device *dev = bq->dev;
int sent = 0, drops = 0, err = 0;
int i;
if (unlikely(!bq->count))
return;
for (i = 0; i < bq->count; i++) {
struct xdp_frame *xdpf = bq->q[i];
prefetch(xdpf);
}
sent = dev->netdev_ops->ndo_xdp_xmit(dev, bq->count, bq->q, flags);
if (sent < 0) {
err = sent;
sent = 0;
goto error;
}
drops = bq->count - sent;
out:
bq->count = 0;
trace_xdp_devmap_xmit(bq->dev_rx, dev, sent, drops, err);
bq->dev_rx = NULL;
__list_del_clearprev(&bq->flush_node);
return;
error:
/* If ndo_xdp_xmit fails with an errno, no frames have been
* xmit'ed and it's our responsibility to them free all.
*/
for (i = 0; i < bq->count; i++) {
struct xdp_frame *xdpf = bq->q[i];
xdp_return_frame_rx_napi(xdpf);
drops++;
}
goto out;
}
/* __dev_flush is called from xdp_do_flush() which _must_ be signaled
* from the driver before returning from its napi->poll() routine. The poll()
* routine is called either from busy_poll context or net_rx_action signaled
* from NET_RX_SOFTIRQ. Either way the poll routine must complete before the
* net device can be torn down. On devmap tear down we ensure the flush list
* is empty before completing to ensure all flush operations have completed.
* When drivers update the bpf program they may need to ensure any flush ops
* are also complete. Using synchronize_rcu or call_rcu will suffice for this
* because both wait for napi context to exit.
*/
void __dev_flush(void)
{
struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
struct xdp_dev_bulk_queue *bq, *tmp;
list_for_each_entry_safe(bq, tmp, flush_list, flush_node)
bq_xmit_all(bq, XDP_XMIT_FLUSH);
}
/* rcu_read_lock (from syscall and BPF contexts) ensures that if a delete and/or
* update happens in parallel here a dev_put wont happen until after reading the
* ifindex.
*/
struct bpf_dtab_netdev *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
{
struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
struct bpf_dtab_netdev *obj;
if (key >= map->max_entries)
return NULL;
obj = READ_ONCE(dtab->netdev_map[key]);
return obj;
}
/* Runs under RCU-read-side, plus in softirq under NAPI protection.
* Thus, safe percpu variable access.
*/
static void bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
struct net_device *dev_rx)
{
struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
struct xdp_dev_bulk_queue *bq = this_cpu_ptr(dev->xdp_bulkq);
if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
bq_xmit_all(bq, 0);
/* Ingress dev_rx will be the same for all xdp_frame's in
* bulk_queue, because bq stored per-CPU and must be flushed
* from net_device drivers NAPI func end.
*/
if (!bq->dev_rx)
bq->dev_rx = dev_rx;
bq->q[bq->count++] = xdpf;
if (!bq->flush_node.prev)
list_add(&bq->flush_node, flush_list);
}
static inline int __xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
struct net_device *dev_rx)
{
struct xdp_frame *xdpf;
int err;
if (!dev->netdev_ops->ndo_xdp_xmit)
return -EOPNOTSUPP;
err = xdp_ok_fwd_dev(dev, xdp->data_end - xdp->data);
if (unlikely(err))
return err;
xdpf = xdp_convert_buff_to_frame(xdp);
if (unlikely(!xdpf))
return -EOVERFLOW;
bq_enqueue(dev, xdpf, dev_rx);
return 0;
}
static struct xdp_buff *dev_map_run_prog(struct net_device *dev,
struct xdp_buff *xdp,
struct bpf_prog *xdp_prog)
{
struct xdp_txq_info txq = { .dev = dev };
u32 act;
xdp_set_data_meta_invalid(xdp);
xdp->txq = &txq;
act = bpf_prog_run_xdp(xdp_prog, xdp);
switch (act) {
case XDP_PASS:
return xdp;
case XDP_DROP:
break;
default:
bpf_warn_invalid_xdp_action(act);
fallthrough;
case XDP_ABORTED:
trace_xdp_exception(dev, xdp_prog, act);
break;
}
xdp_return_buff(xdp);
return NULL;
}
int dev_xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
struct net_device *dev_rx)
{
return __xdp_enqueue(dev, xdp, dev_rx);
}
int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
struct net_device *dev_rx)
{
struct net_device *dev = dst->dev;
if (dst->xdp_prog) {
xdp = dev_map_run_prog(dev, xdp, dst->xdp_prog);
if (!xdp)
return 0;
}
return __xdp_enqueue(dev, xdp, dev_rx);
}
int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
struct bpf_prog *xdp_prog)
{
int err;
err = xdp_ok_fwd_dev(dst->dev, skb->len);
if (unlikely(err))
return err;
skb->dev = dst->dev;
generic_xdp_tx(skb, xdp_prog);
return 0;
}
static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
{
struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
return obj ? &obj->val : NULL;
}
static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key)
{
struct bpf_dtab_netdev *obj = __dev_map_hash_lookup_elem(map,
*(u32 *)key);
return obj ? &obj->val : NULL;
}
static void __dev_map_entry_free(struct rcu_head *rcu)
{
struct bpf_dtab_netdev *dev;
dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
if (dev->xdp_prog)
bpf_prog_put(dev->xdp_prog);
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 as well as any flush operations because call_rcu
* will wait for preempt-disable region to complete, NAPI in this
* context. 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,
struct bpf_devmap_val *val,
unsigned int idx)
{
struct bpf_prog *prog = NULL;
struct bpf_dtab_netdev *dev;
dev = kmalloc_node(sizeof(*dev), GFP_ATOMIC | __GFP_NOWARN,
dtab->map.numa_node);
if (!dev)
return ERR_PTR(-ENOMEM);
dev->dev = dev_get_by_index(net, val->ifindex);
if (!dev->dev)
goto err_out;
if (val->bpf_prog.fd > 0) {
prog = bpf_prog_get_type_dev(val->bpf_prog.fd,
BPF_PROG_TYPE_XDP, false);
if (IS_ERR(prog))
goto err_put_dev;
if (prog->expected_attach_type != BPF_XDP_DEVMAP)
goto err_put_prog;
}
dev->idx = idx;
dev->dtab = dtab;
if (prog) {
dev->xdp_prog = prog;
dev->val.bpf_prog.id = prog->aux->id;
} else {
dev->xdp_prog = NULL;
dev->val.bpf_prog.id = 0;
}
dev->val.ifindex = val->ifindex;
return dev;
err_put_prog:
bpf_prog_put(prog);
err_put_dev:
dev_put(dev->dev);
err_out:
kfree(dev);
return ERR_PTR(-EINVAL);
}
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;
struct bpf_devmap_val val = {};
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;
/* already verified value_size <= sizeof val */
memcpy(&val, value, map->value_size);
if (!val.ifindex) {
dev = NULL;
/* can not specify fd if ifindex is 0 */
if (val.bpf_prog.fd > 0)
return -EINVAL;
} else {
dev = __dev_map_alloc_node(net, dtab, &val, 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;
struct bpf_devmap_val val = {};
u32 idx = *(u32 *)key;
unsigned long flags;
int err = -EEXIST;
/* already verified value_size <= sizeof val */
memcpy(&val, value, map->value_size);
if (unlikely(map_flags > BPF_EXIST || !val.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, &val, 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);
}
static int dev_map_btf_id;
const struct bpf_map_ops dev_map_ops = {
.map_meta_equal = bpf_map_meta_equal,
.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,
.map_btf_name = "bpf_dtab",
.map_btf_id = &dev_map_btf_id,
};
static int dev_map_hash_map_btf_id;
const struct bpf_map_ops dev_map_hash_ops = {
.map_meta_equal = bpf_map_meta_equal,
.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,
.map_btf_name = "bpf_dtab",
.map_btf_id = &dev_map_hash_map_btf_id,
};
static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,
struct net_device *netdev)
{
unsigned long flags;
u32 i;
spin_lock_irqsave(&dtab->index_lock, flags);
for (i = 0; i < dtab->n_buckets; i++) {
struct bpf_dtab_netdev *dev;
struct hlist_head *head;
struct hlist_node *next;
head = dev_map_index_hash(dtab, i);
hlist_for_each_entry_safe(dev, next, head, index_hlist) {
if (netdev != dev->dev)
continue;
dtab->items--;
hlist_del_rcu(&dev->index_hlist);
call_rcu(&dev->rcu, __dev_map_entry_free);
}
}
spin_unlock_irqrestore(&dtab->index_lock, flags);
}
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, cpu;
switch (event) {
case NETDEV_REGISTER:
if (!netdev->netdev_ops->ndo_xdp_xmit || netdev->xdp_bulkq)
break;
/* will be freed in free_netdev() */
netdev->xdp_bulkq =
__alloc_percpu_gfp(sizeof(struct xdp_dev_bulk_queue),
sizeof(void *), GFP_ATOMIC);
if (!netdev->xdp_bulkq)
return NOTIFY_BAD;
for_each_possible_cpu(cpu)
per_cpu_ptr(netdev->xdp_bulkq, cpu)->dev = netdev;
break;
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) {
if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
dev_map_hash_remove_netdev(dtab, netdev);
continue;
}
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)
{
int cpu;
/* 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);
for_each_possible_cpu(cpu)
INIT_LIST_HEAD(&per_cpu(dev_flush_list, cpu));
return 0;
}
subsys_initcall(dev_map_init);