Re: [PATCH bpf-next 1/2] xdp: Move devmap bulk queue into struct net_device
From: Björn Töpel <hidden>
Date: 2020-01-10 15:04:00
Also in:
bpf
On Fri, 10 Jan 2020 at 15:22, Toke Høiland-Jørgensen [off-list ref] wrote:
From: Toke Høiland-Jørgensen <redacted>
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.
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.Nice work, Toke! I'm getting some checkpatch warnings (>80 char lines), other than that: Acked-by: Björn Töpel <redacted>
quoted hunk ↗ jump to hunk
Signed-off-by: Toke Høiland-Jørgensen <redacted> --- include/linux/netdevice.h | 3 ++ include/trace/events/xdp.h | 2 + kernel/bpf/devmap.c | 61 ++++++++++++++++++-------------------------- net/core/dev.c | 2 + 4 files changed, 31 insertions(+), 37 deletions(-)diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 2741aa35bec6..1b2bc2a7522e 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;@@ -1993,6 +1994,8 @@ struct net_device { 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; struct xps_dev_maps __rcu *xps_rxqs_map;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..bcb05cb6b728 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 +530,14 @@ 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 +697,22 @@ 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 deletediff --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);