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-rw-r--r--include/linux/list_nulls.h5
-rw-r--r--include/linux/rculist_nulls.h14
-rw-r--r--kernel/bpf/hashtab.c94
3 files changed, 79 insertions, 34 deletions
diff --git a/include/linux/list_nulls.h b/include/linux/list_nulls.h
index b01fe1009084..87ff4f58a2f0 100644
--- a/include/linux/list_nulls.h
+++ b/include/linux/list_nulls.h
@@ -29,6 +29,11 @@ struct hlist_nulls_node {
((ptr)->first = (struct hlist_nulls_node *) NULLS_MARKER(nulls))
#define hlist_nulls_entry(ptr, type, member) container_of(ptr,type,member)
+
+#define hlist_nulls_entry_safe(ptr, type, member) \
+ ({ typeof(ptr) ____ptr = (ptr); \
+ !is_a_nulls(____ptr) ? hlist_nulls_entry(____ptr, type, member) : NULL; \
+ })
/**
* ptr_is_a_nulls - Test if a ptr is a nulls
* @ptr: ptr to be tested
diff --git a/include/linux/rculist_nulls.h b/include/linux/rculist_nulls.h
index 4ae95f7e8597..a23a33153180 100644
--- a/include/linux/rculist_nulls.h
+++ b/include/linux/rculist_nulls.h
@@ -156,5 +156,19 @@ static inline void hlist_nulls_add_tail_rcu(struct hlist_nulls_node *n,
({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); 1; }); \
pos = rcu_dereference_raw(hlist_nulls_next_rcu(pos)))
+/**
+ * hlist_nulls_for_each_entry_safe -
+ * iterate over list of given type safe against removal of list entry
+ * @tpos: the type * to use as a loop cursor.
+ * @pos: the &struct hlist_nulls_node to use as a loop cursor.
+ * @head: the head for your list.
+ * @member: the name of the hlist_nulls_node within the struct.
+ */
+#define hlist_nulls_for_each_entry_safe(tpos, pos, head, member) \
+ for (({barrier();}), \
+ pos = rcu_dereference_raw(hlist_nulls_first_rcu(head)); \
+ (!is_a_nulls(pos)) && \
+ ({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); \
+ pos = rcu_dereference_raw(hlist_nulls_next_rcu(pos)); 1; });)
#endif
#endif
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 63c86a7be2a1..afe5bab376c9 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -13,11 +13,12 @@
#include <linux/bpf.h>
#include <linux/jhash.h>
#include <linux/filter.h>
+#include <linux/rculist_nulls.h>
#include "percpu_freelist.h"
#include "bpf_lru_list.h"
struct bucket {
- struct hlist_head head;
+ struct hlist_nulls_head head;
raw_spinlock_t lock;
};
@@ -44,7 +45,7 @@ enum extra_elem_state {
/* each htab element is struct htab_elem + key + value */
struct htab_elem {
union {
- struct hlist_node hash_node;
+ struct hlist_nulls_node hash_node;
struct {
void *padding;
union {
@@ -337,7 +338,7 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
goto free_htab;
for (i = 0; i < htab->n_buckets; i++) {
- INIT_HLIST_HEAD(&htab->buckets[i].head);
+ INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i);
raw_spin_lock_init(&htab->buckets[i].lock);
}
@@ -377,28 +378,52 @@ static inline struct bucket *__select_bucket(struct bpf_htab *htab, u32 hash)
return &htab->buckets[hash & (htab->n_buckets - 1)];
}
-static inline struct hlist_head *select_bucket(struct bpf_htab *htab, u32 hash)
+static inline struct hlist_nulls_head *select_bucket(struct bpf_htab *htab, u32 hash)
{
return &__select_bucket(htab, hash)->head;
}
-static struct htab_elem *lookup_elem_raw(struct hlist_head *head, u32 hash,
+/* this lookup function can only be called with bucket lock taken */
+static struct htab_elem *lookup_elem_raw(struct hlist_nulls_head *head, u32 hash,
void *key, u32 key_size)
{
+ struct hlist_nulls_node *n;
struct htab_elem *l;
- hlist_for_each_entry_rcu(l, head, hash_node)
+ hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
if (l->hash == hash && !memcmp(&l->key, key, key_size))
return l;
return NULL;
}
+/* can be called without bucket lock. it will repeat the loop in
+ * the unlikely event when elements moved from one bucket into another
+ * while link list is being walked
+ */
+static struct htab_elem *lookup_nulls_elem_raw(struct hlist_nulls_head *head,
+ u32 hash, void *key,
+ u32 key_size, u32 n_buckets)
+{
+ struct hlist_nulls_node *n;
+ struct htab_elem *l;
+
+again:
+ hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
+ if (l->hash == hash && !memcmp(&l->key, key, key_size))
+ return l;
+
+ if (unlikely(get_nulls_value(n) != (hash & (n_buckets - 1))))
+ goto again;
+
+ return NULL;
+}
+
/* Called from syscall or from eBPF program */
static void *__htab_map_lookup_elem(struct bpf_map *map, void *key)
{
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
- struct hlist_head *head;
+ struct hlist_nulls_head *head;
struct htab_elem *l;
u32 hash, key_size;
@@ -411,7 +436,7 @@ static void *__htab_map_lookup_elem(struct bpf_map *map, void *key)
head = select_bucket(htab, hash);
- l = lookup_elem_raw(head, hash, key, key_size);
+ l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
return l;
}
@@ -444,8 +469,9 @@ static void *htab_lru_map_lookup_elem(struct bpf_map *map, void *key)
static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node)
{
struct bpf_htab *htab = (struct bpf_htab *)arg;
- struct htab_elem *l, *tgt_l;
- struct hlist_head *head;
+ struct htab_elem *l = NULL, *tgt_l;
+ struct hlist_nulls_head *head;
+ struct hlist_nulls_node *n;
unsigned long flags;
struct bucket *b;
@@ -455,9 +481,9 @@ static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node)
raw_spin_lock_irqsave(&b->lock, flags);
- hlist_for_each_entry_rcu(l, head, hash_node)
+ hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
if (l == tgt_l) {
- hlist_del_rcu(&l->hash_node);
+ hlist_nulls_del_rcu(&l->hash_node);
break;
}
@@ -470,7 +496,7 @@ static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node)
static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
{
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
- struct hlist_head *head;
+ struct hlist_nulls_head *head;
struct htab_elem *l, *next_l;
u32 hash, key_size;
int i;
@@ -484,7 +510,7 @@ static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
head = select_bucket(htab, hash);
/* lookup the key */
- l = lookup_elem_raw(head, hash, key, key_size);
+ l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
if (!l) {
i = 0;
@@ -492,7 +518,7 @@ static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
}
/* key was found, get next key in the same bucket */
- next_l = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&l->hash_node)),
+ next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_next_rcu(&l->hash_node)),
struct htab_elem, hash_node);
if (next_l) {
@@ -511,7 +537,7 @@ find_first_elem:
head = select_bucket(htab, i);
/* pick first element in the bucket */
- next_l = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
+ next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_first_rcu(head)),
struct htab_elem, hash_node);
if (next_l) {
/* if it's not empty, just return it */
@@ -676,7 +702,7 @@ static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
{
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
struct htab_elem *l_new = NULL, *l_old;
- struct hlist_head *head;
+ struct hlist_nulls_head *head;
unsigned long flags;
struct bucket *b;
u32 key_size, hash;
@@ -715,9 +741,9 @@ static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
/* add new element to the head of the list, so that
* concurrent search will find it before old elem
*/
- hlist_add_head_rcu(&l_new->hash_node, head);
+ hlist_nulls_add_head_rcu(&l_new->hash_node, head);
if (l_old) {
- hlist_del_rcu(&l_old->hash_node);
+ hlist_nulls_del_rcu(&l_old->hash_node);
free_htab_elem(htab, l_old);
}
ret = 0;
@@ -731,7 +757,7 @@ static int htab_lru_map_update_elem(struct bpf_map *map, void *key, void *value,
{
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
struct htab_elem *l_new, *l_old = NULL;
- struct hlist_head *head;
+ struct hlist_nulls_head *head;
unsigned long flags;
struct bucket *b;
u32 key_size, hash;
@@ -772,10 +798,10 @@ static int htab_lru_map_update_elem(struct bpf_map *map, void *key, void *value,
/* add new element to the head of the list, so that
* concurrent search will find it before old elem
*/
- hlist_add_head_rcu(&l_new->hash_node, head);
+ hlist_nulls_add_head_rcu(&l_new->hash_node, head);
if (l_old) {
bpf_lru_node_set_ref(&l_new->lru_node);
- hlist_del_rcu(&l_old->hash_node);
+ hlist_nulls_del_rcu(&l_old->hash_node);
}
ret = 0;
@@ -796,7 +822,7 @@ static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key,
{
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
struct htab_elem *l_new = NULL, *l_old;
- struct hlist_head *head;
+ struct hlist_nulls_head *head;
unsigned long flags;
struct bucket *b;
u32 key_size, hash;
@@ -835,7 +861,7 @@ static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key,
ret = PTR_ERR(l_new);
goto err;
}
- hlist_add_head_rcu(&l_new->hash_node, head);
+ hlist_nulls_add_head_rcu(&l_new->hash_node, head);
}
ret = 0;
err:
@@ -849,7 +875,7 @@ static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
{
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
struct htab_elem *l_new = NULL, *l_old;
- struct hlist_head *head;
+ struct hlist_nulls_head *head;
unsigned long flags;
struct bucket *b;
u32 key_size, hash;
@@ -897,7 +923,7 @@ static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
} else {
pcpu_copy_value(htab, htab_elem_get_ptr(l_new, key_size),
value, onallcpus);
- hlist_add_head_rcu(&l_new->hash_node, head);
+ hlist_nulls_add_head_rcu(&l_new->hash_node, head);
l_new = NULL;
}
ret = 0;
@@ -925,7 +951,7 @@ static int htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
static int htab_map_delete_elem(struct bpf_map *map, void *key)
{
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
- struct hlist_head *head;
+ struct hlist_nulls_head *head;
struct bucket *b;
struct htab_elem *l;
unsigned long flags;
@@ -945,7 +971,7 @@ static int htab_map_delete_elem(struct bpf_map *map, void *key)
l = lookup_elem_raw(head, hash, key, key_size);
if (l) {
- hlist_del_rcu(&l->hash_node);
+ hlist_nulls_del_rcu(&l->hash_node);
free_htab_elem(htab, l);
ret = 0;
}
@@ -957,7 +983,7 @@ static int htab_map_delete_elem(struct bpf_map *map, void *key)
static int htab_lru_map_delete_elem(struct bpf_map *map, void *key)
{
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
- struct hlist_head *head;
+ struct hlist_nulls_head *head;
struct bucket *b;
struct htab_elem *l;
unsigned long flags;
@@ -977,7 +1003,7 @@ static int htab_lru_map_delete_elem(struct bpf_map *map, void *key)
l = lookup_elem_raw(head, hash, key, key_size);
if (l) {
- hlist_del_rcu(&l->hash_node);
+ hlist_nulls_del_rcu(&l->hash_node);
ret = 0;
}
@@ -992,12 +1018,12 @@ static void delete_all_elements(struct bpf_htab *htab)
int i;
for (i = 0; i < htab->n_buckets; i++) {
- struct hlist_head *head = select_bucket(htab, i);
- struct hlist_node *n;
+ struct hlist_nulls_head *head = select_bucket(htab, i);
+ struct hlist_nulls_node *n;
struct htab_elem *l;
- hlist_for_each_entry_safe(l, n, head, hash_node) {
- hlist_del_rcu(&l->hash_node);
+ hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
+ hlist_nulls_del_rcu(&l->hash_node);
if (l->state != HTAB_EXTRA_ELEM_USED)
htab_elem_free(htab, l);
}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.