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Date: Mon, 13 Jan 2020 19:10:55 +0100
From: Toke Høiland-Jørgensen <toke@...hat.com>
To: netdev@...r.kernel.org
Cc: bpf@...r.kernel.org, Daniel Borkmann <daniel@...earbox.net>,
Alexei Starovoitov <ast@...nel.org>,
David Miller <davem@...emloft.net>,
Jesper Dangaard Brouer <brouer@...hat.com>,
Björn Töpel <bjorn.topel@...il.com>,
John Fastabend <john.fastabend@...il.com>
Subject: [PATCH bpf-next v2 1/2] xdp: Move devmap bulk queue into struct
net_device
From: Toke Høiland-Jørgensen <toke@...hat.com>
Commit 96360004b862 ("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.
Acked-by: Björn Töpel <bjorn.topel@...el.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@...hat.com>
---
include/linux/netdevice.h | 11 +++++---
include/trace/events/xdp.h | 2 +
kernel/bpf/devmap.c | 63 +++++++++++++++++++-------------------------
net/core/dev.c | 2 +
4 files changed, 37 insertions(+), 41 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 2741aa35bec6..1f24405c1ec5 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -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;
@@ -2001,8 +2000,12 @@ 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;
diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h
index a7378bcd9928..72bad13d4a3c 100644
--- a/include/trace/events/xdp.h
+++ b/include/trace/events/xdp.h
@@ -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;
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index da9c832fc5c8..030d125c3839 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -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
diff --git a/net/core/dev.c b/net/core/dev.c
index d99f88c58636..e7802a41ae7f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -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);
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