[PATCH v7 bpf-next 4/9] cpumap: formalize map value as a named struct

Lorenzo Bianconi
2020-07-14T13:57:19Z

As it has been already done for devmap, introduce 'struct bpf_cpumap_val'
to formalize the expected values that can be passed in for a CPUMAP.
Update cpumap code to use the struct.

Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
include/uapi/linux/bpf.h | 9 +++++++++
kernel/bpf/cpumap.c | 28 +++++++++++++++-------------
tools/include/uapi/linux/bpf.h | 9 +++++++++
3 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 5e386389913a..109623527358 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3849,6 +3849,15 @@ struct bpf_devmap_val {
} bpf_prog;
};

+/* CPUMAP map-value layout
+ *
+ * The struct data-layout of map-value is a configuration interface.
+ * New members can only be added to the end of this structure.
+ */
+struct bpf_cpumap_val {
+ __u32 qsize; /* queue size to remote target CPU */
+};
+
enum sk_action {
SK_DROP = 0,
SK_PASS,
diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
index 323c91c4fab0..ff48dc00e8d0 100644
--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -52,7 +52,6 @@ struct xdp_bulk_queue {
struct bpf_cpu_map_entry {
u32 cpu; /* kthread CPU and map index */
int map_id; /* Back reference to map */
- u32 qsize; /* Queue size placeholder for map lookup */

/* XDP can run multiple RX-ring queues, need __percpu enqueue store */
struct xdp_bulk_queue __percpu *bulkq;
@@ -62,10 +61,13 @@ struct bpf_cpu_map_entry {
/* Queue with potential multi-producers, and single-consumer kthread */
struct ptr_ring *queue;
struct task_struct *kthread;
- struct work_struct kthread_stop_wq;
+
+ struct bpf_cpumap_val value;

atomic_t refcnt; /* Control when this struct can be free'ed */
struct rcu_head rcu;
+
+ struct work_struct kthread_stop_wq;
};

struct bpf_cpu_map {
@@ -307,8 +309,8 @@ static int cpu_map_kthread_run(void *data)
return 0;
}

-static struct bpf_cpu_map_entry *__cpu_map_entry_alloc(u32 qsize, u32 cpu,
- int map_id)
+static struct bpf_cpu_map_entry *
+__cpu_map_entry_alloc(struct bpf_cpumap_val *value, u32 cpu, int map_id)
{
gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
struct bpf_cpu_map_entry *rcpu;
@@ -338,13 +340,13 @@ static struct bpf_cpu_map_entry *__cpu_map_entry_alloc(u32 qsize, u32 cpu,
if (!rcpu->queue)
goto free_bulkq;

- err = ptr_ring_init(rcpu->queue, qsize, gfp);
+ err = ptr_ring_init(rcpu->queue, value->qsize, gfp);
if (err)
goto free_queue;

rcpu->cpu = cpu;
rcpu->map_id = map_id;
- rcpu->qsize = qsize;
+ rcpu->value.qsize = value->qsize;

/* Setup kthread */
rcpu->kthread = kthread_create_on_node(cpu_map_kthread_run, rcpu, numa,
@@ -437,12 +439,12 @@ static int cpu_map_update_elem(struct bpf_map *map, void *key, void *value,
u64 map_flags)
{
struct bpf_cpu_map *cmap = container_of(map, struct bpf_cpu_map, map);
+ struct bpf_cpumap_val cpumap_value = {};
struct bpf_cpu_map_entry *rcpu;
-
/* Array index key correspond to CPU number */
u32 key_cpu = *(u32 *)key;
- /* Value is the queue size */
- u32 qsize = *(u32 *)value;
+
+ memcpy(&cpumap_value, value, map->value_size);

if (unlikely(map_flags > BPF_EXIST))
return -EINVAL;
@@ -450,18 +452,18 @@ static int cpu_map_update_elem(struct bpf_map *map, void *key, void *value,
return -E2BIG;
if (unlikely(map_flags == BPF_NOEXIST))
return -EEXIST;
- if (unlikely(qsize > 16384)) /* sanity limit on qsize */
+ if (unlikely(cpumap_value.qsize > 16384)) /* sanity limit on qsize */
return -EOVERFLOW;

/* Make sure CPU is a valid possible cpu */
if (key_cpu >= nr_cpumask_bits || !cpu_possible(key_cpu))
return -ENODEV;

- if (qsize == 0) {
+ if (cpumap_value.qsize == 0) {
rcpu = NULL; /* Same as deleting */
} else {
/* Updating qsize cause re-allocation of bpf_cpu_map_entry */
- rcpu = __cpu_map_entry_alloc(qsize, key_cpu, map->id);
+ rcpu = __cpu_map_entry_alloc(&cpumap_value, key_cpu, map->id);
if (!rcpu)
return -ENOMEM;
rcpu->cmap = cmap;
@@ -523,7 +525,7 @@ static void *cpu_map_lookup_elem(struct bpf_map *map, void *key)
struct bpf_cpu_map_entry *rcpu =
__cpu_map_lookup_elem(map, *(u32 *)key);

- return rcpu ? &rcpu->qsize : NULL;
+ return rcpu ? &rcpu->value : NULL;
}

static int cpu_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 5e386389913a..109623527358 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3849,6 +3849,15 @@ struct bpf_devmap_val {
} bpf_prog;
};

+/* CPUMAP map-value layout
+ *
+ * The struct data-layout of map-value is a configuration interface.
+ * New members can only be added to the end of this structure.
+ */
+struct bpf_cpumap_val {
+ __u32 qsize; /* queue size to remote target CPU */
+};
+
enum sk_action {
SK_DROP = 0,
SK_PASS,
--
2.26.2