Commit 855d8e77 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Alexei Starovoitov

bpf: af_unix: Use batching algorithm in bpf unix iter.

The commit 04c7820b ("bpf: tcp: Bpf iter batching and lock_sock")
introduces the batching algorithm to iterate TCP sockets with more
consistency.

This patch uses the same algorithm to iterate AF_UNIX sockets.
Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.co.jp>
Link: https://lore.kernel.org/r/20220113002849.4384-3-kuniyu@amazon.co.jpSigned-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 4408d55a
......@@ -3356,6 +3356,15 @@ static const struct seq_operations unix_seq_ops = {
};
#if IS_BUILTIN(CONFIG_UNIX) && defined(CONFIG_BPF_SYSCALL)
struct bpf_unix_iter_state {
struct seq_net_private p;
unsigned int cur_sk;
unsigned int end_sk;
unsigned int max_sk;
struct sock **batch;
bool st_bucket_done;
};
struct bpf_iter__unix {
__bpf_md_ptr(struct bpf_iter_meta *, meta);
__bpf_md_ptr(struct unix_sock *, unix_sk);
......@@ -3374,24 +3383,156 @@ static int unix_prog_seq_show(struct bpf_prog *prog, struct bpf_iter_meta *meta,
return bpf_iter_run_prog(prog, &ctx);
}
static int bpf_iter_unix_hold_batch(struct seq_file *seq, struct sock *start_sk)
{
struct bpf_unix_iter_state *iter = seq->private;
unsigned int expected = 1;
struct sock *sk;
sock_hold(start_sk);
iter->batch[iter->end_sk++] = start_sk;
for (sk = sk_next(start_sk); sk; sk = sk_next(sk)) {
if (sock_net(sk) != seq_file_net(seq))
continue;
if (iter->end_sk < iter->max_sk) {
sock_hold(sk);
iter->batch[iter->end_sk++] = sk;
}
expected++;
}
spin_unlock(&unix_table_locks[start_sk->sk_hash]);
return expected;
}
static void bpf_iter_unix_put_batch(struct bpf_unix_iter_state *iter)
{
while (iter->cur_sk < iter->end_sk)
sock_put(iter->batch[iter->cur_sk++]);
}
static int bpf_iter_unix_realloc_batch(struct bpf_unix_iter_state *iter,
unsigned int new_batch_sz)
{
struct sock **new_batch;
new_batch = kvmalloc(sizeof(*new_batch) * new_batch_sz,
GFP_USER | __GFP_NOWARN);
if (!new_batch)
return -ENOMEM;
bpf_iter_unix_put_batch(iter);
kvfree(iter->batch);
iter->batch = new_batch;
iter->max_sk = new_batch_sz;
return 0;
}
static struct sock *bpf_iter_unix_batch(struct seq_file *seq,
loff_t *pos)
{
struct bpf_unix_iter_state *iter = seq->private;
unsigned int expected;
bool resized = false;
struct sock *sk;
if (iter->st_bucket_done)
*pos = set_bucket_offset(get_bucket(*pos) + 1, 1);
again:
/* Get a new batch */
iter->cur_sk = 0;
iter->end_sk = 0;
sk = unix_get_first(seq, pos);
if (!sk)
return NULL; /* Done */
expected = bpf_iter_unix_hold_batch(seq, sk);
if (iter->end_sk == expected) {
iter->st_bucket_done = true;
return sk;
}
if (!resized && !bpf_iter_unix_realloc_batch(iter, expected * 3 / 2)) {
resized = true;
goto again;
}
return sk;
}
static void *bpf_iter_unix_seq_start(struct seq_file *seq, loff_t *pos)
{
if (!*pos)
return SEQ_START_TOKEN;
/* bpf iter does not support lseek, so it always
* continue from where it was stop()-ped.
*/
return bpf_iter_unix_batch(seq, pos);
}
static void *bpf_iter_unix_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
struct bpf_unix_iter_state *iter = seq->private;
struct sock *sk;
/* Whenever seq_next() is called, the iter->cur_sk is
* done with seq_show(), so advance to the next sk in
* the batch.
*/
if (iter->cur_sk < iter->end_sk)
sock_put(iter->batch[iter->cur_sk++]);
++*pos;
if (iter->cur_sk < iter->end_sk)
sk = iter->batch[iter->cur_sk];
else
sk = bpf_iter_unix_batch(seq, pos);
return sk;
}
static int bpf_iter_unix_seq_show(struct seq_file *seq, void *v)
{
struct bpf_iter_meta meta;
struct bpf_prog *prog;
struct sock *sk = v;
uid_t uid;
bool slow;
int ret;
if (v == SEQ_START_TOKEN)
return 0;
slow = lock_sock_fast(sk);
if (unlikely(sk_unhashed(sk))) {
ret = SEQ_SKIP;
goto unlock;
}
uid = from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk));
meta.seq = seq;
prog = bpf_iter_get_info(&meta, false);
return unix_prog_seq_show(prog, &meta, v, uid);
ret = unix_prog_seq_show(prog, &meta, v, uid);
unlock:
unlock_sock_fast(sk, slow);
return ret;
}
static void bpf_iter_unix_seq_stop(struct seq_file *seq, void *v)
{
struct bpf_unix_iter_state *iter = seq->private;
struct bpf_iter_meta meta;
struct bpf_prog *prog;
......@@ -3402,12 +3543,13 @@ static void bpf_iter_unix_seq_stop(struct seq_file *seq, void *v)
(void)unix_prog_seq_show(prog, &meta, v, 0);
}
unix_seq_stop(seq, v);
if (iter->cur_sk < iter->end_sk)
bpf_iter_unix_put_batch(iter);
}
static const struct seq_operations bpf_iter_unix_seq_ops = {
.start = unix_seq_start,
.next = unix_seq_next,
.start = bpf_iter_unix_seq_start,
.next = bpf_iter_unix_seq_next,
.stop = bpf_iter_unix_seq_stop,
.show = bpf_iter_unix_seq_show,
};
......@@ -3456,11 +3598,39 @@ static struct pernet_operations unix_net_ops = {
DEFINE_BPF_ITER_FUNC(unix, struct bpf_iter_meta *meta,
struct unix_sock *unix_sk, uid_t uid)
#define INIT_BATCH_SZ 16
static int bpf_iter_init_unix(void *priv_data, struct bpf_iter_aux_info *aux)
{
struct bpf_unix_iter_state *iter = priv_data;
int err;
err = bpf_iter_init_seq_net(priv_data, aux);
if (err)
return err;
err = bpf_iter_unix_realloc_batch(iter, INIT_BATCH_SZ);
if (err) {
bpf_iter_fini_seq_net(priv_data);
return err;
}
return 0;
}
static void bpf_iter_fini_unix(void *priv_data)
{
struct bpf_unix_iter_state *iter = priv_data;
bpf_iter_fini_seq_net(priv_data);
kvfree(iter->batch);
}
static const struct bpf_iter_seq_info unix_seq_info = {
.seq_ops = &bpf_iter_unix_seq_ops,
.init_seq_private = bpf_iter_init_seq_net,
.fini_seq_private = bpf_iter_fini_seq_net,
.seq_priv_size = sizeof(struct seq_net_private),
.init_seq_private = bpf_iter_init_unix,
.fini_seq_private = bpf_iter_fini_unix,
.seq_priv_size = sizeof(struct bpf_unix_iter_state),
};
static struct bpf_iter_reg unix_reg_info = {
......
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