This patch change map_lookup_elem() and map_update_elem() function to use u64 temp variable if the key_size or value_size is less than u64, we don't need use kmalloc() for these small variables.
Signed-off-by: yalin wang <yalin.wang2...@gmail.com> --- kernel/bpf/syscall.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index f640e5f..c82d7bf 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -189,7 +189,8 @@ static int map_lookup_elem(union bpf_attr *attr) void __user *uvalue = u64_to_ptr(attr->value); int ufd = attr->map_fd; struct bpf_map *map; - void *key, *value, *ptr; + u64 key_buf, value_buf; + void *key = &key_buf, *value = &value_buf, *ptr; struct fd f; int err; @@ -202,7 +203,8 @@ static int map_lookup_elem(union bpf_attr *attr) return PTR_ERR(map); err = -ENOMEM; - key = kmalloc(map->key_size, GFP_USER); + if (map->key_size > sizeof(u64)) + key = kmalloc(map->key_size, GFP_USER); if (!key) goto err_put; @@ -211,7 +213,8 @@ static int map_lookup_elem(union bpf_attr *attr) goto free_key; err = -ENOMEM; - value = kmalloc(map->value_size, GFP_USER); + if (map->value_size > sizeof(u64)) + value = kmalloc(map->value_size, GFP_USER); if (!value) goto free_key; @@ -232,9 +235,11 @@ static int map_lookup_elem(union bpf_attr *attr) err = 0; free_value: - kfree(value); + if (value != &value_buf) + kfree(value); free_key: - kfree(key); + if (key != &key_buf) + kfree(key); err_put: fdput(f); return err; @@ -248,7 +253,8 @@ static int map_update_elem(union bpf_attr *attr) void __user *uvalue = u64_to_ptr(attr->value); int ufd = attr->map_fd; struct bpf_map *map; - void *key, *value; + u64 key_buf, value_buf; + void *key = &key_buf, *value = &value_buf; struct fd f; int err; @@ -261,7 +267,8 @@ static int map_update_elem(union bpf_attr *attr) return PTR_ERR(map); err = -ENOMEM; - key = kmalloc(map->key_size, GFP_USER); + if (map->key_size > sizeof(u64)) + key = kmalloc(map->key_size, GFP_USER); if (!key) goto err_put; @@ -270,7 +277,8 @@ static int map_update_elem(union bpf_attr *attr) goto free_key; err = -ENOMEM; - value = kmalloc(map->value_size, GFP_USER); + if (map->value_size > sizeof(u64)) + value = kmalloc(map->value_size, GFP_USER); if (!value) goto free_key; @@ -286,9 +294,11 @@ static int map_update_elem(union bpf_attr *attr) rcu_read_unlock(); free_value: - kfree(value); + if (value != &value_buf) + kfree(value); free_key: - kfree(key); + if (key != &key_buf) + kfree(key); err_put: fdput(f); return err; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/