| Message ID | 157893905569.861394.457637639114847149.stgit@toke.dk |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | xdp: Introduce bulking for non-map XDP_REDIRECT | expand |
Toke Høiland-Jørgensen wrote: > From: Toke Høiland-Jørgensen <toke@redhat.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@intel.com> > Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> > --- LGTM. I didn't check the net_device layout with pahole though so I'm trusting they are good from v1 discussion. Acked-by: John Fastabend <john.fastabend@gmail.com>
On Mon, 13 Jan 2020 19:10:55 +0100 Toke Høiland-Jørgensen <toke@redhat.com> wrote: > 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 [...] > @@ -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); Hmm ... I don't like that we lose the map_id and map_index identifier. This is part of our troubleshooting interface. > bq->dev_rx = NULL; > __list_del_clearprev(&bq->flush_node); > return 0;
Jesper Dangaard Brouer <brouer@redhat.com> writes: > On Mon, 13 Jan 2020 19:10:55 +0100 > Toke Høiland-Jørgensen <toke@redhat.com> wrote: > >> 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 > [...] >> @@ -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); > > Hmm ... I don't like that we lose the map_id and map_index identifier. > This is part of our troubleshooting interface. Hmm, I guess I can take another look at whether there's a way to avoid that. Any ideas? -Toke
John Fastabend <john.fastabend@gmail.com> writes: > Toke Høiland-Jørgensen wrote: >> From: Toke Høiland-Jørgensen <toke@redhat.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@intel.com> >> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> >> --- > > LGTM. I didn't check the net_device layout with pahole though so I'm > trusting they are good from v1 discussion. I believe so; looks like this now: /* --- 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 */ int * pcpu_refcnt; /* 1136 8 */ struct list_head todo_list; /* 1144 16 */ /* --- cacheline 18 boundary (1152 bytes) was 8 bytes ago --- */ -Toke
On Wed, 15 Jan 2020 23:11:21 +0100 Toke Høiland-Jørgensen <toke@redhat.com> wrote: > Jesper Dangaard Brouer <brouer@redhat.com> writes: > > > On Mon, 13 Jan 2020 19:10:55 +0100 > > Toke Høiland-Jørgensen <toke@redhat.com> wrote: > > > >> 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 > > [...] > >> @@ -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); > > > > Hmm ... I don't like that we lose the map_id and map_index identifier. > > This is part of our troubleshooting interface. > > Hmm, I guess I can take another look at whether there's a way to avoid > that. Any ideas? Looking at the code and the other tracepoints... I will actually suggest to remove these two arguments, because the trace_xdp_redirect_map tracepoint also contains the ifindex'es, and to troubleshoot people can record both tracepoints and do the correlation themselves. When changing the tracepoint I would like to keep member 'drops' and 'sent' at the same struct offsets. As our xdp_monitor example reads these and I hope we can kept it working this way. I've coded it up, and tested it. The new xdp_monitor will work on older kernels, but the old xdp_monitor will fail attaching on newer kernels. I think this is fair enough, as we are backwards compatible. [PATCH] devmap: adjust tracepoing after Tokes changes From: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> --- include/trace/events/xdp.h | 29 ++++++++++++----------------- kernel/bpf/devmap.c | 2 +- samples/bpf/xdp_monitor_kern.c | 8 +++----- 3 files changed, 16 insertions(+), 23 deletions(-) diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h index cf568a38f852..f1e64689ce94 100644 --- a/include/trace/events/xdp.h +++ b/include/trace/events/xdp.h @@ -247,43 +247,38 @@ TRACE_EVENT(xdp_cpumap_enqueue, TRACE_EVENT(xdp_devmap_xmit, - TP_PROTO(const struct bpf_map *map, u32 map_index, - int sent, int drops, - const struct net_device *from_dev, - const struct net_device *to_dev, int err), + TP_PROTO(const struct net_device *from_dev, + const struct net_device *to_dev, + int sent, int drops, int err), - TP_ARGS(map, map_index, sent, drops, from_dev, to_dev, err), + TP_ARGS(from_dev, to_dev, sent, drops, err), TP_STRUCT__entry( - __field(int, map_id) + __field(int, from_ifindex) __field(u32, act) - __field(u32, map_index) + __field(int, to_ifindex) __field(int, drops) __field(int, sent) - __field(int, from_ifindex) - __field(int, to_ifindex) __field(int, err) ), TP_fast_assign( - __entry->map_id = map ? map->id : 0; + __entry->from_ifindex = from_dev->ifindex; __entry->act = XDP_REDIRECT; - __entry->map_index = map_index; + __entry->to_ifindex = to_dev->ifindex; __entry->drops = drops; __entry->sent = sent; - __entry->from_ifindex = from_dev->ifindex; - __entry->to_ifindex = to_dev->ifindex; __entry->err = err; ), TP_printk("ndo_xdp_xmit" - " map_id=%d map_index=%d action=%s" + " from_ifindex=%d to_ifindex=%d action=%s" " sent=%d drops=%d" - " from_ifindex=%d to_ifindex=%d err=%d", - __entry->map_id, __entry->map_index, + " err=%d", + __entry->from_ifindex, __entry->to_ifindex, __print_symbolic(__entry->act, __XDP_ACT_SYM_TAB), __entry->sent, __entry->drops, - __entry->from_ifindex, __entry->to_ifindex, __entry->err) + __entry->err) ); /* Expect users already include <net/xdp.h>, but not xdp_priv.h */ diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index db32272c4f77..1b4bfe4e06d6 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -340,7 +340,7 @@ static int bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags) out: bq->count = 0; - trace_xdp_devmap_xmit(NULL, 0, sent, drops, bq->dev_rx, dev, err); + trace_xdp_devmap_xmit(bq->dev_rx, dev, sent, drops, err); bq->dev_rx = NULL; __list_del_clearprev(&bq->flush_node); return 0; diff --git a/samples/bpf/xdp_monitor_kern.c b/samples/bpf/xdp_monitor_kern.c index ad10fe700d7d..39458a44472e 100644 --- a/samples/bpf/xdp_monitor_kern.c +++ b/samples/bpf/xdp_monitor_kern.c @@ -222,14 +222,12 @@ struct bpf_map_def SEC("maps") devmap_xmit_cnt = { */ struct devmap_xmit_ctx { u64 __pad; // First 8 bytes are not accessible by bpf code - int map_id; // offset:8; size:4; signed:1; + int from_ifindex; // offset:8; size:4; signed:1; u32 act; // offset:12; size:4; signed:0; - u32 map_index; // offset:16; size:4; signed:0; + int to_ifindex; // offset:16; size:4; signed:1; int drops; // offset:20; size:4; signed:1; int sent; // offset:24; size:4; signed:1; - int from_ifindex; // offset:28; size:4; signed:1; - int to_ifindex; // offset:32; size:4; signed:1; - int err; // offset:36; size:4; signed:1; + int err; // offset:28; size:4; signed:1; }; SEC("tracepoint/xdp/xdp_devmap_xmit")
Jesper Dangaard Brouer <brouer@redhat.com> writes: > On Wed, 15 Jan 2020 23:11:21 +0100 > Toke Høiland-Jørgensen <toke@redhat.com> wrote: > >> Jesper Dangaard Brouer <brouer@redhat.com> writes: >> >> > On Mon, 13 Jan 2020 19:10:55 +0100 >> > Toke Høiland-Jørgensen <toke@redhat.com> wrote: >> > >> >> 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 >> > [...] >> >> @@ -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); >> > >> > Hmm ... I don't like that we lose the map_id and map_index identifier. >> > This is part of our troubleshooting interface. >> >> Hmm, I guess I can take another look at whether there's a way to avoid >> that. Any ideas? > > Looking at the code and the other tracepoints... > > I will actually suggest to remove these two arguments, because the > trace_xdp_redirect_map tracepoint also contains the ifindex'es, and to > troubleshoot people can record both tracepoints and do the correlation > themselves. > > When changing the tracepoint I would like to keep member 'drops' and > 'sent' at the same struct offsets. As our xdp_monitor example reads > these and I hope we can kept it working this way. > > I've coded it up, and tested it. The new xdp_monitor will work on > older kernels, but the old xdp_monitor will fail attaching on newer > kernels. I think this is fair enough, as we are backwards compatible. SGTM - thanks! I'll respin and include this :) -Toke
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);