[PATCH bpf-next v2 4/8] xsk: make xskmap flush_list common for all map instances

Björn Töpel
2019-12-19T06:10:39Z

From: Björn Töpel <bjorn.topel@intel.com>

The xskmap flush list is used to track entries that need to flushed
from via the xdp_do_flush_map() function. This list used to be
per-map, but there is really no reason for that. Instead make the
flush list global for all xskmaps, which simplifies __xsk_map_flush()
and xsk_map_alloc().

Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
---
include/net/xdp_sock.h | 11 ++++-------
kernel/bpf/xskmap.c | 18 +++---------------
net/core/filter.c | 9 ++++-----
net/xdp/xsk.c | 17 +++++++++--------
4 files changed, 20 insertions(+), 35 deletions(-)

diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index e3780e4b74e1..48594740d67c 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -72,7 +72,6 @@ struct xdp_umem {

struct xsk_map {
struct bpf_map map;
- struct list_head __percpu *flush_list;
spinlock_t lock; /* Synchronize map updates */
struct xdp_sock *xsk_map[];
};
@@ -139,9 +138,8 @@ void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs,
struct xdp_sock **map_entry);
int xsk_map_inc(struct xsk_map *map);
void xsk_map_put(struct xsk_map *map);
-int __xsk_map_redirect(struct bpf_map *map, struct xdp_buff *xdp,
- struct xdp_sock *xs);
-void __xsk_map_flush(struct bpf_map *map);
+int __xsk_map_redirect(struct xdp_sock *xs, struct xdp_buff *xdp);
+void __xsk_map_flush(void);

static inline struct xdp_sock *__xsk_map_lookup_elem(struct bpf_map *map,
u32 key)
@@ -369,13 +367,12 @@ static inline u64 xsk_umem_adjust_offset(struct xdp_umem *umem, u64 handle,
return 0;
}

-static inline int __xsk_map_redirect(struct bpf_map *map, struct xdp_buff *xdp,
- struct xdp_sock *xs)
+static inline int __xsk_map_redirect(struct xdp_sock *xs, struct xdp_buff *xdp)
{
return -EOPNOTSUPP;
}

-static inline void __xsk_map_flush(struct bpf_map *map)
+static inline void __xsk_map_flush(void)
{
}

diff --git a/kernel/bpf/xskmap.c b/kernel/bpf/xskmap.c
index 90c4fce1c981..2cc5c8f4c800 100644
--- a/kernel/bpf/xskmap.c
+++ b/kernel/bpf/xskmap.c
@@ -72,9 +72,9 @@ static void xsk_map_sock_delete(struct xdp_sock *xs,
static struct bpf_map *xsk_map_alloc(union bpf_attr *attr)
{
struct bpf_map_memory mem;
- int cpu, err, numa_node;
+ int err, numa_node;
struct xsk_map *m;
- u64 cost, size;
+ u64 size;

if (!capable(CAP_NET_ADMIN))
return ERR_PTR(-EPERM);
@@ -86,9 +86,8 @@ static struct bpf_map *xsk_map_alloc(union bpf_attr *attr)

numa_node = bpf_map_attr_numa_node(attr);
size = struct_size(m, xsk_map, attr->max_entries);
- cost = size + array_size(sizeof(*m->flush_list), num_possible_cpus());

- err = bpf_map_charge_init(&mem, cost);
+ err = bpf_map_charge_init(&mem, size);
if (err < 0)
return ERR_PTR(err);

@@ -102,16 +101,6 @@ static struct bpf_map *xsk_map_alloc(union bpf_attr *attr)
bpf_map_charge_move(&m->map.memory, &mem);
spin_lock_init(&m->lock);

- m->flush_list = alloc_percpu(struct list_head);
- if (!m->flush_list) {
- bpf_map_charge_finish(&m->map.memory);
- bpf_map_area_free(m);
- return ERR_PTR(-ENOMEM);
- }
-
- for_each_possible_cpu(cpu)
- INIT_LIST_HEAD(per_cpu_ptr(m->flush_list, cpu));
-
return &m->map;
}

@@ -121,7 +110,6 @@ static void xsk_map_free(struct bpf_map *map)

bpf_clear_redirect_map(map);
synchronize_net();
- free_percpu(m->flush_list);
bpf_map_area_free(m);
}

diff --git a/net/core/filter.c b/net/core/filter.c
index a411f7835dee..c51678c473c5 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3511,8 +3511,7 @@ xdp_do_redirect_slow(struct net_device *dev, struct xdp_buff *xdp,

static int __bpf_tx_xdp_map(struct net_device *dev_rx, void *fwd,
struct bpf_map *map,
- struct xdp_buff *xdp,
- u32 index)
+ struct xdp_buff *xdp)
{
int err;

@@ -3537,7 +3536,7 @@ static int __bpf_tx_xdp_map(struct net_device *dev_rx, void *fwd,
case BPF_MAP_TYPE_XSKMAP: {
struct xdp_sock *xs = fwd;

- err = __xsk_map_redirect(map, xdp, xs);
+ err = __xsk_map_redirect(xs, xdp);
return err;
}
default:
@@ -3562,7 +3561,7 @@ void xdp_do_flush_map(void)
__cpu_map_flush(map);
break;
case BPF_MAP_TYPE_XSKMAP:
- __xsk_map_flush(map);
+ __xsk_map_flush();
break;
default:
break;
@@ -3619,7 +3618,7 @@ static int xdp_do_redirect_map(struct net_device *dev, struct xdp_buff *xdp,
if (ri->map_to_flush && unlikely(ri->map_to_flush != map))
xdp_do_flush_map();

- err = __bpf_tx_xdp_map(dev, fwd, map, xdp, index);
+ err = __bpf_tx_xdp_map(dev, fwd, map, xdp);
if (unlikely(err))
goto err;

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 956793893c9d..e45c27f5cfca 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -31,6 +31,8 @@

#define TX_BATCH_SIZE 16

+static DEFINE_PER_CPU(struct list_head, xskmap_flush_list);
+
bool xsk_is_setup_for_bpf_map(struct xdp_sock *xs)
{
return READ_ONCE(xs->rx) && READ_ONCE(xs->umem) &&
@@ -264,11 +266,9 @@ int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
return err;
}

-int __xsk_map_redirect(struct bpf_map *map, struct xdp_buff *xdp,
- struct xdp_sock *xs)
+int __xsk_map_redirect(struct xdp_sock *xs, struct xdp_buff *xdp)
{
- struct xsk_map *m = container_of(map, struct xsk_map, map);
- struct list_head *flush_list = this_cpu_ptr(m->flush_list);
+ struct list_head *flush_list = this_cpu_ptr(&xskmap_flush_list);
int err;

err = xsk_rcv(xs, xdp);
@@ -281,10 +281,9 @@ int __xsk_map_redirect(struct bpf_map *map, struct xdp_buff *xdp,
return 0;
}

-void __xsk_map_flush(struct bpf_map *map)
+void __xsk_map_flush(void)
{
- struct xsk_map *m = container_of(map, struct xsk_map, map);
- struct list_head *flush_list = this_cpu_ptr(m->flush_list);
+ struct list_head *flush_list = this_cpu_ptr(&xskmap_flush_list);
struct xdp_sock *xs, *tmp;

list_for_each_entry_safe(xs, tmp, flush_list, flush_node) {
@@ -1177,7 +1176,7 @@ static struct pernet_operations xsk_net_ops = {

static int __init xsk_init(void)
{
- int err;
+ int err, cpu;

err = proto_register(&xsk_proto, 0 /* no slab */);
if (err)
@@ -1195,6 +1194,8 @@ static int __init xsk_init(void)
if (err)
goto out_pernet;

+ for_each_possible_cpu(cpu)
+ INIT_LIST_HEAD(&per_cpu(xskmap_flush_list, cpu));
return 0;

out_pernet:
--
2.20.1