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tcp: seq_file: Add listening_get_first()

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The current listening_get_next() is overloaded by passing
NULL to the 2nd arg, like listening_get_next(seq, NULL), to
mean get_first().

This patch moves some logic from the listening_get_next() into
a new function listening_get_first().  It will be equivalent
to the current established_get_first() and established_get_next()
setup.  get_first() is to find a non empty bucket and return
the first sk.  get_next() is to find the next sk of the current
bucket and then resorts to get_first() if the current bucket is
exhausted.

The next patch is to move the listener seq_file iteration from
listening_hash (port only) to lhash2 (port+addr).
Separating out listening_get_first() from listening_get_next()
here will make the following lhash2 changes cleaner and easier to
follow.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210701200600.1035353-1-kafai@fb.com
This commit is contained in:
Martin KaFai Lau 2021-07-01 13:06:00 -07:00 committed by Andrii Nakryiko
parent 62001372c2
commit b72acf4501
1 changed files with 39 additions and 20 deletions
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59
net/ipv4/tcp_ipv4.c
View File

@ -2288,10 +2288,38 @@ static bool seq_sk_match(struct seq_file *seq, const struct sock *sk)
net_eq(sock_net(sk), seq_file_net(seq)));
}
/*
* Get next listener socket follow cur. If cur is NULL, get first socket
* starting from bucket given in st->bucket; when st->bucket is zero the
* very first socket in the hash table is returned.
/* Find a non empty bucket (starting from st->bucket)
* and return the first sk from it.
*/
static void *listening_get_first(struct seq_file *seq)
{
struct tcp_iter_state *st = seq->private;
st->offset = 0;
for (; st->bucket < INET_LHTABLE_SIZE; st->bucket++) {
struct inet_listen_hashbucket *ilb;
struct hlist_nulls_node *node;
struct sock *sk;
ilb = &tcp_hashinfo.listening_hash[st->bucket];
if (hlist_nulls_empty(&ilb->nulls_head))
continue;
spin_lock(&ilb->lock);
sk_nulls_for_each(sk, node, &ilb->nulls_head) {
if (seq_sk_match(seq, sk))
return sk;
}
spin_unlock(&ilb->lock);
}
return NULL;
}
/* Find the next sk of "cur" within the same bucket (i.e. st->bucket).
* If "cur" is the last one in the st->bucket,
* call listening_get_first() to return the first sk of the next
* non empty bucket.
*/
static void *listening_get_next(struct seq_file *seq, void *cur)
{
@ -2300,29 +2328,20 @@ static void *listening_get_next(struct seq_file *seq, void *cur)
struct hlist_nulls_node *node;
struct sock *sk = cur;
if (!sk) {
get_head:
ilb = &tcp_hashinfo.listening_hash[st->bucket];
spin_lock(&ilb->lock);
sk = sk_nulls_head(&ilb->nulls_head);
st->offset = 0;
goto get_sk;
}
ilb = &tcp_hashinfo.listening_hash[st->bucket];
++st->num;
++st->offset;
sk = sk_nulls_next(sk);
get_sk:
sk_nulls_for_each_from(sk, node) {
if (seq_sk_match(seq, sk))
return sk;
}
ilb = &tcp_hashinfo.listening_hash[st->bucket];
spin_unlock(&ilb->lock);
st->offset = 0;
if (++st->bucket < INET_LHTABLE_SIZE)
goto get_head;
return NULL;
++st->bucket;
return listening_get_first(seq);
}
static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
@ -2332,7 +2351,7 @@ static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
st->bucket = 0;
st->offset = 0;
rc = listening_get_next(seq, NULL);
rc = listening_get_first(seq);
while (rc && *pos) {
rc = listening_get_next(seq, rc);
@ -2440,7 +2459,7 @@ static void *tcp_seek_last_pos(struct seq_file *seq)
if (st->bucket >= INET_LHTABLE_SIZE)
break;
st->state = TCP_SEQ_STATE_LISTENING;
rc = listening_get_next(seq, NULL);
rc = listening_get_first(seq);
while (offset-- && rc && bucket == st->bucket)
rc = listening_get_next(seq, rc);
if (rc)