Commit 4cc9ce4e authored by KP Singh's avatar KP Singh Committed by Alexei Starovoitov
Browse files

bpf: Generalize caching for sk_storage. 

Provide the a ability to define local storage caches on a per-object
type basis. The caches and caching indices for different objects should
not be inter-mixed as suggested in:

  https://lore.kernel.org/bpf/20200630193441.kdwnkestulg5erii@kafai-mbp.dhcp.thefacebook.com/



  "Caching a sk-storage at idx=0 of a sk should not stop an
  inode-storage to be cached at the same idx of a inode."

Signed-off-by: default avatarKP Singh <kpsingh@google.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200825182919.1118197-3-kpsingh@chromium.org
parent 1f00d375

include/net/bpf_sk_storage.h

+19 −0
Original line number Diff line number Diff line
@@ -3,6 +3,9 @@ 
#ifndef _BPF_SK_STORAGE_H

#define _BPF_SK_STORAGE_H



#include <linux/types.h>

#include <linux/spinlock.h>



struct sock;



void bpf_sk_storage_free(struct sock *sk);
@@ -15,6 +18,22 @@ struct sk_buff; 
struct nlattr;

struct sock;



#define BPF_LOCAL_STORAGE_CACHE_SIZE	16



struct bpf_local_storage_cache {

	spinlock_t idx_lock;

	u64 idx_usage_counts[BPF_LOCAL_STORAGE_CACHE_SIZE];

};



#define DEFINE_BPF_STORAGE_CACHE(name)				\

static struct bpf_local_storage_cache name = {			\

	.idx_lock = __SPIN_LOCK_UNLOCKED(name.idx_lock),	\

}



u16 bpf_local_storage_cache_idx_get(struct bpf_local_storage_cache *cache);

void bpf_local_storage_cache_idx_free(struct bpf_local_storage_cache *cache,

				      u16 idx);



#ifdef CONFIG_BPF_SYSCALL

int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk);

struct bpf_sk_storage_diag *

net/core/bpf_sk_storage.c

+15 −16
Original line number Diff line number Diff line
@@ -14,6 +14,8 @@ 


#define BPF_LOCAL_STORAGE_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_CLONE)



DEFINE_BPF_STORAGE_CACHE(sk_cache);



struct bpf_local_storage_map_bucket {

	struct hlist_head list;

	raw_spinlock_t lock;
@@ -78,10 +80,6 @@ struct bpf_local_storage_elem { 
#define SELEM(_SDATA)							\

	container_of((_SDATA), struct bpf_local_storage_elem, sdata)

#define SDATA(_SELEM) (&(_SELEM)->sdata)

#define BPF_LOCAL_STORAGE_CACHE_SIZE	16



static DEFINE_SPINLOCK(cache_idx_lock);

static u64 cache_idx_usage_counts[BPF_LOCAL_STORAGE_CACHE_SIZE];



struct bpf_local_storage {

	struct bpf_local_storage_data __rcu *cache[BPF_LOCAL_STORAGE_CACHE_SIZE];
@@ -521,16 +519,16 @@ static int sk_storage_delete(struct sock *sk, struct bpf_map *map) 
	return 0;

}



static u16 cache_idx_get(void)

u16 bpf_local_storage_cache_idx_get(struct bpf_local_storage_cache *cache)

{

	u64 min_usage = U64_MAX;

	u16 i, res = 0;



	spin_lock(&cache_idx_lock);

	spin_lock(&cache->idx_lock);



	for (i = 0; i < BPF_LOCAL_STORAGE_CACHE_SIZE; i++) {

		if (cache_idx_usage_counts[i] < min_usage) {

			min_usage = cache_idx_usage_counts[i];

		if (cache->idx_usage_counts[i] < min_usage) {

			min_usage = cache->idx_usage_counts[i];

			res = i;



			/* Found a free cache_idx */
@@ -538,18 +536,19 @@ static u16 cache_idx_get(void) 
				break;

		}

	}

	cache_idx_usage_counts[res]++;

	cache->idx_usage_counts[res]++;



	spin_unlock(&cache_idx_lock);

	spin_unlock(&cache->idx_lock);



	return res;

}



static void cache_idx_free(u16 idx)

void bpf_local_storage_cache_idx_free(struct bpf_local_storage_cache *cache,

				      u16 idx)

{

	spin_lock(&cache_idx_lock);

	cache_idx_usage_counts[idx]--;

	spin_unlock(&cache_idx_lock);

	spin_lock(&cache->idx_lock);

	cache->idx_usage_counts[idx]--;

	spin_unlock(&cache->idx_lock);

}



/* Called by __sk_destruct() & bpf_sk_storage_clone() */
@@ -601,7 +600,7 @@ static void bpf_local_storage_map_free(struct bpf_map *map) 


	smap = (struct bpf_local_storage_map *)map;



	cache_idx_free(smap->cache_idx);

	bpf_local_storage_cache_idx_free(&sk_cache, smap->cache_idx);



	/* Note that this map might be concurrently cloned from

	 * bpf_sk_storage_clone. Wait for any existing bpf_sk_storage_clone
@@ -718,7 +717,7 @@ static struct bpf_map *bpf_local_storage_map_alloc(union bpf_attr *attr) 


	smap->elem_size =

		sizeof(struct bpf_local_storage_elem) + attr->value_size;

	smap->cache_idx = cache_idx_get();

	smap->cache_idx = bpf_local_storage_cache_idx_get(&sk_cache);



	return &smap->map;

}