Revision b4cd08aa1f53c831e67dc5c6bc9f9acff27abcba authored by Wolfram Sang on 16 December 2015, 19:05:18 UTC, committed by Wolfram Sang on 19 December 2015, 11:00:37 UTC
When we also are I2C slave, we need to disable runtime PM because the address detection mechanism needs to be active all the time. However, we can reenable runtime PM once the slave instance was unregistered. So, use pm_runtime_get_sync/put to achieve this, since it has proper refcounting. pm_runtime_allow/forbid is like a global knob controllable from userspace which is unsuitable here. Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de> Cc: stable@kernel.org
1 parent e79e72c
hashtab.c
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#include <linux/bpf.h>
#include <linux/jhash.h>
#include <linux/filter.h>
#include <linux/vmalloc.h>
struct bpf_htab {
struct bpf_map map;
struct hlist_head *buckets;
raw_spinlock_t lock;
u32 count; /* number of elements in this hashtable */
u32 n_buckets; /* number of hash buckets */
u32 elem_size; /* size of each element in bytes */
};
/* each htab element is struct htab_elem + key + value */
struct htab_elem {
struct hlist_node hash_node;
struct rcu_head rcu;
u32 hash;
char key[0] __aligned(8);
};
/* Called from syscall */
static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
{
struct bpf_htab *htab;
int err, i;
htab = kzalloc(sizeof(*htab), GFP_USER);
if (!htab)
return ERR_PTR(-ENOMEM);
/* mandatory map attributes */
htab->map.key_size = attr->key_size;
htab->map.value_size = attr->value_size;
htab->map.max_entries = attr->max_entries;
/* check sanity of attributes.
* value_size == 0 may be allowed in the future to use map as a set
*/
err = -EINVAL;
if (htab->map.max_entries == 0 || htab->map.key_size == 0 ||
htab->map.value_size == 0)
goto free_htab;
/* hash table size must be power of 2 */
htab->n_buckets = roundup_pow_of_two(htab->map.max_entries);
err = -E2BIG;
if (htab->map.key_size > MAX_BPF_STACK)
/* eBPF programs initialize keys on stack, so they cannot be
* larger than max stack size
*/
goto free_htab;
err = -ENOMEM;
/* prevent zero size kmalloc and check for u32 overflow */
if (htab->n_buckets == 0 ||
htab->n_buckets > U32_MAX / sizeof(struct hlist_head))
goto free_htab;
htab->buckets = kmalloc_array(htab->n_buckets, sizeof(struct hlist_head),
GFP_USER | __GFP_NOWARN);
if (!htab->buckets) {
htab->buckets = vmalloc(htab->n_buckets * sizeof(struct hlist_head));
if (!htab->buckets)
goto free_htab;
}
for (i = 0; i < htab->n_buckets; i++)
INIT_HLIST_HEAD(&htab->buckets[i]);
raw_spin_lock_init(&htab->lock);
htab->count = 0;
htab->elem_size = sizeof(struct htab_elem) +
round_up(htab->map.key_size, 8) +
htab->map.value_size;
htab->map.pages = round_up(htab->n_buckets * sizeof(struct hlist_head) +
htab->elem_size * htab->map.max_entries,
PAGE_SIZE) >> PAGE_SHIFT;
return &htab->map;
free_htab:
kfree(htab);
return ERR_PTR(err);
}
static inline u32 htab_map_hash(const void *key, u32 key_len)
{
return jhash(key, key_len, 0);
}
static inline struct hlist_head *select_bucket(struct bpf_htab *htab, u32 hash)
{
return &htab->buckets[hash & (htab->n_buckets - 1)];
}
static struct htab_elem *lookup_elem_raw(struct hlist_head *head, u32 hash,
void *key, u32 key_size)
{
struct htab_elem *l;
hlist_for_each_entry_rcu(l, head, hash_node)
if (l->hash == hash && !memcmp(&l->key, key, key_size))
return l;
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 htab_elem *l;
u32 hash, key_size;
/* Must be called with rcu_read_lock. */
WARN_ON_ONCE(!rcu_read_lock_held());
key_size = map->key_size;
hash = htab_map_hash(key, key_size);
head = select_bucket(htab, hash);
l = lookup_elem_raw(head, hash, key, key_size);
if (l)
return l->key + round_up(map->key_size, 8);
return NULL;
}
/* Called from syscall */
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 htab_elem *l, *next_l;
u32 hash, key_size;
int i;
WARN_ON_ONCE(!rcu_read_lock_held());
key_size = map->key_size;
hash = htab_map_hash(key, key_size);
head = select_bucket(htab, hash);
/* lookup the key */
l = lookup_elem_raw(head, hash, key, key_size);
if (!l) {
i = 0;
goto find_first_elem;
}
/* key was found, get next key in the same bucket */
next_l = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&l->hash_node)),
struct htab_elem, hash_node);
if (next_l) {
/* if next elem in this hash list is non-zero, just return it */
memcpy(next_key, next_l->key, key_size);
return 0;
}
/* no more elements in this hash list, go to the next bucket */
i = hash & (htab->n_buckets - 1);
i++;
find_first_elem:
/* iterate over buckets */
for (; i < htab->n_buckets; i++) {
head = select_bucket(htab, i);
/* pick first element in the bucket */
next_l = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
struct htab_elem, hash_node);
if (next_l) {
/* if it's not empty, just return it */
memcpy(next_key, next_l->key, key_size);
return 0;
}
}
/* itereated over all buckets and all elements */
return -ENOENT;
}
/* Called from syscall or from eBPF program */
static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
u64 map_flags)
{
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
struct htab_elem *l_new, *l_old;
struct hlist_head *head;
unsigned long flags;
u32 key_size;
int ret;
if (map_flags > BPF_EXIST)
/* unknown flags */
return -EINVAL;
WARN_ON_ONCE(!rcu_read_lock_held());
/* allocate new element outside of lock */
l_new = kmalloc(htab->elem_size, GFP_ATOMIC);
if (!l_new)
return -ENOMEM;
key_size = map->key_size;
memcpy(l_new->key, key, key_size);
memcpy(l_new->key + round_up(key_size, 8), value, map->value_size);
l_new->hash = htab_map_hash(l_new->key, key_size);
/* bpf_map_update_elem() can be called in_irq() */
raw_spin_lock_irqsave(&htab->lock, flags);
head = select_bucket(htab, l_new->hash);
l_old = lookup_elem_raw(head, l_new->hash, key, key_size);
if (!l_old && unlikely(htab->count >= map->max_entries)) {
/* if elem with this 'key' doesn't exist and we've reached
* max_entries limit, fail insertion of new elem
*/
ret = -E2BIG;
goto err;
}
if (l_old && map_flags == BPF_NOEXIST) {
/* elem already exists */
ret = -EEXIST;
goto err;
}
if (!l_old && map_flags == BPF_EXIST) {
/* elem doesn't exist, cannot update it */
ret = -ENOENT;
goto err;
}
/* 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);
if (l_old) {
hlist_del_rcu(&l_old->hash_node);
kfree_rcu(l_old, rcu);
} else {
htab->count++;
}
raw_spin_unlock_irqrestore(&htab->lock, flags);
return 0;
err:
raw_spin_unlock_irqrestore(&htab->lock, flags);
kfree(l_new);
return ret;
}
/* Called from syscall or from eBPF program */
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 htab_elem *l;
unsigned long flags;
u32 hash, key_size;
int ret = -ENOENT;
WARN_ON_ONCE(!rcu_read_lock_held());
key_size = map->key_size;
hash = htab_map_hash(key, key_size);
raw_spin_lock_irqsave(&htab->lock, flags);
head = select_bucket(htab, hash);
l = lookup_elem_raw(head, hash, key, key_size);
if (l) {
hlist_del_rcu(&l->hash_node);
htab->count--;
kfree_rcu(l, rcu);
ret = 0;
}
raw_spin_unlock_irqrestore(&htab->lock, flags);
return ret;
}
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 htab_elem *l;
hlist_for_each_entry_safe(l, n, head, hash_node) {
hlist_del_rcu(&l->hash_node);
htab->count--;
kfree(l);
}
}
}
/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
static void htab_map_free(struct bpf_map *map)
{
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
/* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
* so the programs (can be more than one that used this map) were
* disconnected from events. Wait for outstanding critical sections in
* these programs to complete
*/
synchronize_rcu();
/* some of kfree_rcu() callbacks for elements of this map may not have
* executed. It's ok. Proceed to free residual elements and map itself
*/
delete_all_elements(htab);
kvfree(htab->buckets);
kfree(htab);
}
static const struct bpf_map_ops htab_ops = {
.map_alloc = htab_map_alloc,
.map_free = htab_map_free,
.map_get_next_key = htab_map_get_next_key,
.map_lookup_elem = htab_map_lookup_elem,
.map_update_elem = htab_map_update_elem,
.map_delete_elem = htab_map_delete_elem,
};
static struct bpf_map_type_list htab_type __read_mostly = {
.ops = &htab_ops,
.type = BPF_MAP_TYPE_HASH,
};
static int __init register_htab_map(void)
{
bpf_register_map_type(&htab_type);
return 0;
}
late_initcall(register_htab_map);
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