[PATCH bpf-next v2 6/8] xdp: make cpumap flush_list common for all map instances

Björn Töpel
2019-12-19T06:10:46Z

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

The cpumap 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 devmaps, which simplifies __cpu_map_flush()
and cpu_map_alloc().

Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
---
include/linux/bpf.h | 4 ++--
kernel/bpf/cpumap.c | 36 ++++++++++++++++++------------------
net/core/filter.c | 2 +-
3 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 31191804ca09..8f3e00c84f39 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -966,7 +966,7 @@ int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
struct bpf_prog *xdp_prog);

struct bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key);
-void __cpu_map_flush(struct bpf_map *map);
+void __cpu_map_flush(void);
int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_buff *xdp,
struct net_device *dev_rx);

@@ -1097,7 +1097,7 @@ struct bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key)
return NULL;
}

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

diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
index f9deed659798..70f71b154fa5 100644
--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -72,17 +72,18 @@ struct bpf_cpu_map {
struct bpf_map map;
/* Below members specific for map type */
struct bpf_cpu_map_entry **cpu_map;
- struct list_head __percpu *flush_list;
};

+static DEFINE_PER_CPU(struct list_head, cpu_map_flush_list);
+
static int bq_flush_to_queue(struct xdp_bulk_queue *bq);

static struct bpf_map *cpu_map_alloc(union bpf_attr *attr)
{
struct bpf_cpu_map *cmap;
int err = -ENOMEM;
- int ret, cpu;
u64 cost;
+ int ret;

if (!capable(CAP_SYS_ADMIN))
return ERR_PTR(-EPERM);
@@ -106,7 +107,6 @@ static struct bpf_map *cpu_map_alloc(union bpf_attr *attr)

/* make sure page count doesn't overflow */
cost = (u64) cmap->map.max_entries * sizeof(struct bpf_cpu_map_entry *);
- cost += sizeof(struct list_head) * num_possible_cpus();

/* Notice returns -EPERM on if map size is larger than memlock limit */
ret = bpf_map_charge_init(&cmap->map.memory, cost);
@@ -115,23 +115,14 @@ static struct bpf_map *cpu_map_alloc(union bpf_attr *attr)
goto free_cmap;
}

- cmap->flush_list = alloc_percpu(struct list_head);
- if (!cmap->flush_list)
- goto free_charge;
-
- for_each_possible_cpu(cpu)
- INIT_LIST_HEAD(per_cpu_ptr(cmap->flush_list, cpu));
-
/* Alloc array for possible remote "destination" CPUs */
cmap->cpu_map = bpf_map_area_alloc(cmap->map.max_entries *
sizeof(struct bpf_cpu_map_entry *),
cmap->map.numa_node);
if (!cmap->cpu_map)
- goto free_percpu;
+ goto free_charge;

return &cmap->map;
-free_percpu:
- free_percpu(cmap->flush_list);
free_charge:
bpf_map_charge_finish(&cmap->map.memory);
free_cmap:
@@ -526,7 +517,6 @@ static void cpu_map_free(struct bpf_map *map)
/* bq flush and cleanup happens after RCU grace-period */
__cpu_map_entry_replace(cmap, i, NULL); /* call_rcu */
}
- free_percpu(cmap->flush_list);
bpf_map_area_free(cmap->cpu_map);
kfree(cmap);
}
@@ -618,7 +608,7 @@ static int bq_flush_to_queue(struct xdp_bulk_queue *bq)
*/
static int bq_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_frame *xdpf)
{
- struct list_head *flush_list = this_cpu_ptr(rcpu->cmap->flush_list);
+ struct list_head *flush_list = this_cpu_ptr(&cpu_map_flush_list);
struct xdp_bulk_queue *bq = this_cpu_ptr(rcpu->bulkq);

if (unlikely(bq->count == CPU_MAP_BULK_SIZE))
@@ -657,10 +647,9 @@ int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_buff *xdp,
return 0;
}

-void __cpu_map_flush(struct bpf_map *map)
+void __cpu_map_flush(void)
{
- struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map);
- struct list_head *flush_list = this_cpu_ptr(cmap->flush_list);
+ struct list_head *flush_list = this_cpu_ptr(&cpu_map_flush_list);
struct xdp_bulk_queue *bq, *tmp;

list_for_each_entry_safe(bq, tmp, flush_list, flush_node) {
@@ -670,3 +659,14 @@ void __cpu_map_flush(struct bpf_map *map)
wake_up_process(bq->obj->kthread);
}
}
+
+static int __init cpu_map_init(void)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu)
+ INIT_LIST_HEAD(&per_cpu(cpu_map_flush_list, cpu));
+ return 0;
+}
+
+subsys_initcall(cpu_map_init);
diff --git a/net/core/filter.c b/net/core/filter.c
index b7570cb84902..c706325b3e66 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3558,7 +3558,7 @@ void xdp_do_flush_map(void)
__dev_map_flush();
break;
case BPF_MAP_TYPE_CPUMAP:
- __cpu_map_flush(map);
+ __cpu_map_flush();
break;
case BPF_MAP_TYPE_XSKMAP:
__xsk_map_flush();
--
2.20.1