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xdp: Move devmap bulk queue into struct net_device

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Commit 96360004b8 ("xdp: Make devmap flush_list common for all map
instances"), changed devmap flushing to be a global operation instead of a
per-map operation. However, the queue structure used for bulking was still
allocated as part of the containing map.

This patch moves the devmap bulk queue into struct net_device. The
motivation for this is reusing it for the non-map variant of XDP_REDIRECT,
which will be changed in a subsequent commit.  To avoid other fields of
struct net_device moving to different cache lines, we also move a couple of
other members around.

We defer the actual allocation of the bulk queue structure until the
NETDEV_REGISTER notification devmap.c. This makes it possible to check for
ndo_xdp_xmit support before allocating the structure, which is not possible
at the time struct net_device is allocated. However, we keep the freeing in
free_netdev() to avoid adding another RCU callback on NETDEV_UNREGISTER.

Because of this change, we lose the reference back to the map that
originated the redirect, so change the tracepoint to always return 0 as the
map ID and index. Otherwise no functional change is intended with this
patch.

After this patch, the relevant part of struct net_device looks like this,
according to pahole:

	/* --- cacheline 14 boundary (896 bytes) --- */
	struct netdev_queue *      _tx __attribute__((__aligned__(64))); /*   896     8 */
	unsigned int               num_tx_queues;        /*   904     4 */
	unsigned int               real_num_tx_queues;   /*   908     4 */
	struct Qdisc *             qdisc;                /*   912     8 */
	unsigned int               tx_queue_len;         /*   920     4 */
	spinlock_t                 tx_global_lock;       /*   924     4 */
	struct xdp_dev_bulk_queue * xdp_bulkq;           /*   928     8 */
	struct xps_dev_maps *      xps_cpus_map;         /*   936     8 */
	struct xps_dev_maps *      xps_rxqs_map;         /*   944     8 */
	struct mini_Qdisc *        miniq_egress;         /*   952     8 */
	/* --- cacheline 15 boundary (960 bytes) --- */
	struct hlist_head  qdisc_hash[16];               /*   960   128 */
	/* --- cacheline 17 boundary (1088 bytes) --- */
	struct timer_list  watchdog_timer;               /*  1088    40 */

	/* XXX last struct has 4 bytes of padding */

	int                        watchdog_timeo;       /*  1128     4 */

	/* XXX 4 bytes hole, try to pack */

	struct list_head   todo_list;                    /*  1136    16 */
	/* --- cacheline 18 boundary (1152 bytes) --- */

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/157918768397.1458396.12673224324627072349.stgit@toke.dk
This commit is contained in:
Toke Høiland-Jørgensen 2020-01-16 16:14:44 +01:00 committed by Alexei Starovoitov
parent 20f21d98cf
commit 75ccae62cb
4 changed files with 38 additions and 42 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

13
include/linux/netdevice.h
View file

@ -876,6 +876,7 @@ enum bpf_netdev_command {
struct bpf_prog_offload_ops;
struct netlink_ext_ack;
struct xdp_umem;
struct xdp_dev_bulk_queue;
struct netdev_bpf {
enum bpf_netdev_command command;
@ -1986,12 +1987,10 @@ struct net_device {
unsigned int num_tx_queues;
unsigned int real_num_tx_queues;
struct Qdisc *qdisc;
#ifdef CONFIG_NET_SCHED
DECLARE_HASHTABLE (qdisc_hash, 4);
#endif
unsigned int tx_queue_len;
spinlock_t tx_global_lock;
int watchdog_timeo;
struct xdp_dev_bulk_queue __percpu *xdp_bulkq;
#ifdef CONFIG_XPS
struct xps_dev_maps __rcu *xps_cpus_map;
@ -2001,11 +2000,15 @@ struct net_device {
struct mini_Qdisc __rcu *miniq_egress;
#endif
#ifdef CONFIG_NET_SCHED
DECLARE_HASHTABLE (qdisc_hash, 4);
#endif
/* These may be needed for future network-power-down code. */
struct timer_list watchdog_timer;
int watchdog_timeo;
int __percpu *pcpu_refcnt;
struct list_head todo_list;
int __percpu *pcpu_refcnt;
struct list_head link_watch_list;

2
include/trace/events/xdp.h
View file

@ -278,7 +278,7 @@ TRACE_EVENT(xdp_devmap_xmit,
),
TP_fast_assign(
__entry->map_id = map->id;
__entry->map_id = map ? map->id : 0;
__entry->act = XDP_REDIRECT;
__entry->map_index = map_index;
__entry->drops = drops;

63
kernel/bpf/devmap.c
View file

@ -53,13 +53,11 @@
(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
#define DEV_MAP_BULK_SIZE 16
struct bpf_dtab_netdev;
struct xdp_bulk_queue {
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;
struct bpf_dtab_netdev *obj;
unsigned int count;
};
@ -67,9 +65,8 @@ 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 xdp_bulk_queue __percpu *bulkq;
struct rcu_head rcu;
unsigned int idx; /* keep track of map index for tracepoint */
unsigned int idx;
};
struct bpf_dtab {
@ -219,7 +216,6 @@ static void dev_map_free(struct bpf_map *map)
hlist_for_each_entry_safe(dev, next, head, index_hlist) {
hlist_del_rcu(&dev->index_hlist);
free_percpu(dev->bulkq);
dev_put(dev->dev);
kfree(dev);
}
@ -234,7 +230,6 @@ static void dev_map_free(struct bpf_map *map)
if (!dev)
continue;
free_percpu(dev->bulkq);
dev_put(dev->dev);
kfree(dev);
}
@ -320,10 +315,9 @@ static int dev_map_hash_get_next_key(struct bpf_map *map, void *key,
return -ENOENT;
}
static int bq_xmit_all(struct xdp_bulk_queue *bq, u32 flags)
static int bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
{
struct bpf_dtab_netdev *obj = bq->obj;
struct net_device *dev = obj->dev;
struct net_device *dev = bq->dev;
int sent = 0, drops = 0, err = 0;
int i;
@ -346,8 +340,7 @@ static int bq_xmit_all(struct xdp_bulk_queue *bq, u32 flags)
out:
bq->count = 0;
trace_xdp_devmap_xmit(&obj->dtab->map, obj->idx,
sent, drops, bq->dev_rx, dev, err);
trace_xdp_devmap_xmit(NULL, 0, sent, drops, bq->dev_rx, dev, err);
bq->dev_rx = NULL;
__list_del_clearprev(&bq->flush_node);
return 0;
@ -374,7 +367,7 @@ static int bq_xmit_all(struct xdp_bulk_queue *bq, u32 flags)
void __dev_map_flush(void)
{
struct list_head *flush_list = this_cpu_ptr(&dev_map_flush_list);
struct xdp_bulk_queue *bq, *tmp;
struct xdp_dev_bulk_queue *bq, *tmp;
rcu_read_lock();
list_for_each_entry_safe(bq, tmp, flush_list, flush_node)
@ -401,12 +394,12 @@ struct bpf_dtab_netdev *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
/* Runs under RCU-read-side, plus in softirq under NAPI protection.
* Thus, safe percpu variable access.
*/
static int bq_enqueue(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf,
static int bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
struct net_device *dev_rx)
{
struct list_head *flush_list = this_cpu_ptr(&dev_map_flush_list);
struct xdp_bulk_queue *bq = this_cpu_ptr(obj->bulkq);
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);
@ -444,7 +437,7 @@ int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
if (unlikely(!xdpf))
return -EOVERFLOW;
return bq_enqueue(dst, xdpf, dev_rx);
return bq_enqueue(dev, xdpf, dev_rx);
}
int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
@ -483,7 +476,6 @@ static void __dev_map_entry_free(struct rcu_head *rcu)
struct bpf_dtab_netdev *dev;
dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
free_percpu(dev->bulkq);
dev_put(dev->dev);
kfree(dev);
}
@ -538,30 +530,15 @@ static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
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);
dev = kmalloc_node(sizeof(*dev), GFP_ATOMIC | __GFP_NOWARN,
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);
}
@ -721,9 +698,23 @@ static int dev_map_notification(struct notifier_block *notifier,
{
struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
struct bpf_dtab *dtab;
int i;
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

2
net/core/dev.c
View file

@ -9847,6 +9847,8 @@ void free_netdev(struct net_device *dev)
free_percpu(dev->pcpu_refcnt);
dev->pcpu_refcnt = NULL;
free_percpu(dev->xdp_bulkq);
dev->xdp_bulkq = NULL;
netdev_unregister_lockdep_key(dev);