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tcp: relax listening_hash operations 

softirq handlers use RCU protection to lookup listeners,
and write operations all happen from process context.
We do not need to block BH for dump operations.

Also SYN_RECV since request sockets are stored in the ehash table :

 1) inet_diag_dump_icsk() no longer need to clear
    cb->args[3] and cb->args[4] that were used as cursors while
    iterating the old per listener hash table.

 2) Also factorize a test : No need to scan listening_hash[]
    if r->id.idiag_dport is not zero.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
zero-colors
Eric Dumazet 2016-10-19 21:24:58 -07:00 committed by David S. Miller
parent 25c07e2c5e
commit 9652dc2eb9
2 changed files with 7 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
net/ipv4/inet_diag.c
View File

@ -863,7 +863,7 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb,
s_num = num = cb->args[2];
if (cb->args[0] == 0) {
if (!(idiag_states & TCPF_LISTEN))
if (!(idiag_states & TCPF_LISTEN) || r->id.idiag_dport)
goto skip_listen_ht;
for (i = s_i; i < INET_LHTABLE_SIZE; i++) {
@ -872,7 +872,7 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb,
num = 0;
ilb = &hashinfo->listening_hash[i];
spin_lock_bh(&ilb->lock);
spin_lock(&ilb->lock);
sk_for_each(sk, &ilb->head) {
struct inet_sock *inet = inet_sk(sk);
@ -892,26 +892,18 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb,
r->id.idiag_sport)
goto next_listen;
if (r->id.idiag_dport ||
cb->args[3] > 0)
goto next_listen;
if (inet_csk_diag_dump(sk, skb, cb, r,
bc, net_admin) < 0) {
spin_unlock_bh(&ilb->lock);
spin_unlock(&ilb->lock);
goto done;
}
next_listen:
cb->args[3] = 0;
cb->args[4] = 0;
++num;
}
spin_unlock_bh(&ilb->lock);
spin_unlock(&ilb->lock);
s_num = 0;
cb->args[3] = 0;
cb->args[4] = 0;
}
skip_listen_ht:
cb->args[0] = 1;

6
net/ipv4/tcp_ipv4.c
View File

@ -1893,7 +1893,7 @@ static void *listening_get_next(struct seq_file *seq, void *cur)
if (!sk) {
get_head:
ilb = &tcp_hashinfo.listening_hash[st->bucket];
spin_lock_bh(&ilb->lock);
spin_lock(&ilb->lock);
sk = sk_head(&ilb->head);
st->offset = 0;
goto get_sk;
@ -1911,7 +1911,7 @@ get_sk:
return sk;
icsk = inet_csk(sk);
}
spin_unlock_bh(&ilb->lock);
spin_unlock(&ilb->lock);
st->offset = 0;
if (++st->bucket < INET_LHTABLE_SIZE)
goto get_head;
@ -2119,7 +2119,7 @@ static void tcp_seq_stop(struct seq_file *seq, void *v)
switch (st->state) {
case TCP_SEQ_STATE_LISTENING:
if (v != SEQ_START_TOKEN)
spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock);
spin_unlock(&tcp_hashinfo.listening_hash[st->bucket].lock);
break;
case TCP_SEQ_STATE_ESTABLISHED:
if (v)