forked from luck/tmp_suning_uos_patched
tcp: no longer hold ehash lock while calling tcp_get_info()
We had various problems in the past in tcp_get_info() and used
specific synchronization to avoid deadlocks.
We would like to add more instrumentation points for TCP, and
avoiding grabing socket lock in tcp_getinfo() was too costly.
Being able to lock the socket allows to provide consistent set
of fields.
inet_diag_dump_icsk() can make sure ehash locks are not
held any more when tcp_get_info() is called.
We can remove syncp added in commit d654976cbf
("tcp: fix a potential deadlock in tcp_get_info()"), but we need
to use lock_sock_fast() instead of spin_lock_bh() since TCP input
path can now be run from process context.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
ccbf3bfaee
commit
67db3e4bfb
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@ -176,8 +176,6 @@ struct tcp_sock {
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* sum(delta(snd_una)), or how many bytes
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* were acked.
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*/
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struct u64_stats_sync syncp; /* protects 64bit vars (cf tcp_get_info()) */
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u32 snd_una; /* First byte we want an ack for */
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u32 snd_sml; /* Last byte of the most recently transmitted small packet */
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u32 rcv_tstamp; /* timestamp of last received ACK (for keepalives) */
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@ -861,10 +861,11 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb,
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struct netlink_callback *cb,
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const struct inet_diag_req_v2 *r, struct nlattr *bc)
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{
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struct net *net = sock_net(skb->sk);
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int i, num, s_i, s_num;
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u32 idiag_states = r->idiag_states;
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bool net_admin = netlink_net_capable(cb->skb, CAP_NET_ADMIN);
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struct net *net = sock_net(skb->sk);
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u32 idiag_states = r->idiag_states;
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int i, num, s_i, s_num;
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struct sock *sk;
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if (idiag_states & TCPF_SYN_RECV)
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idiag_states |= TCPF_NEW_SYN_RECV;
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@ -877,7 +878,6 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb,
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for (i = s_i; i < INET_LHTABLE_SIZE; i++) {
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struct inet_listen_hashbucket *ilb;
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struct sock *sk;
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num = 0;
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ilb = &hashinfo->listening_hash[i];
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@ -922,13 +922,14 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb,
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if (!(idiag_states & ~TCPF_LISTEN))
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goto out;
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#define SKARR_SZ 16
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for (i = s_i; i <= hashinfo->ehash_mask; i++) {
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struct inet_ehash_bucket *head = &hashinfo->ehash[i];
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spinlock_t *lock = inet_ehash_lockp(hashinfo, i);
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struct hlist_nulls_node *node;
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struct sock *sk;
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num = 0;
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struct sock *sk_arr[SKARR_SZ];
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int num_arr[SKARR_SZ];
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int idx, accum, res;
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if (hlist_nulls_empty(&head->chain))
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continue;
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@ -936,9 +937,12 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb,
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if (i > s_i)
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s_num = 0;
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next_chunk:
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num = 0;
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accum = 0;
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spin_lock_bh(lock);
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sk_nulls_for_each(sk, node, &head->chain) {
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int state, res;
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int state;
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if (!net_eq(sock_net(sk), net))
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continue;
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@ -962,21 +966,35 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb,
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if (!inet_diag_bc_sk(bc, sk))
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goto next_normal;
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res = sk_diag_fill(sk, skb, r,
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sock_hold(sk);
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num_arr[accum] = num;
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sk_arr[accum] = sk;
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if (++accum == SKARR_SZ)
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break;
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next_normal:
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++num;
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}
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spin_unlock_bh(lock);
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res = 0;
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for (idx = 0; idx < accum; idx++) {
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if (res >= 0) {
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res = sk_diag_fill(sk_arr[idx], skb, r,
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sk_user_ns(NETLINK_CB(cb->skb).sk),
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NETLINK_CB(cb->skb).portid,
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cb->nlh->nlmsg_seq, NLM_F_MULTI,
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cb->nlh, net_admin);
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if (res < 0) {
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spin_unlock_bh(lock);
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goto done;
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if (res < 0)
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num = num_arr[idx];
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}
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next_normal:
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++num;
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sock_gen_put(sk_arr[idx]);
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}
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spin_unlock_bh(lock);
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if (res < 0)
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break;
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cond_resched();
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if (accum == SKARR_SZ) {
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s_num = num + 1;
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goto next_chunk;
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}
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}
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done:
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@ -405,7 +405,6 @@ void tcp_init_sock(struct sock *sk)
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tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
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tp->snd_cwnd_clamp = ~0;
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tp->mss_cache = TCP_MSS_DEFAULT;
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u64_stats_init(&tp->syncp);
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tp->reordering = sock_net(sk)->ipv4.sysctl_tcp_reordering;
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tcp_enable_early_retrans(tp);
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@ -2710,9 +2709,8 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info)
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const struct tcp_sock *tp = tcp_sk(sk); /* iff sk_type == SOCK_STREAM */
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const struct inet_connection_sock *icsk = inet_csk(sk);
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u32 now = tcp_time_stamp, intv;
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unsigned int start;
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int notsent_bytes;
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u64 rate64;
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bool slow;
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u32 rate;
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memset(info, 0, sizeof(*info));
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@ -2792,17 +2790,17 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info)
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info->tcpi_total_retrans = tp->total_retrans;
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do {
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start = u64_stats_fetch_begin_irq(&tp->syncp);
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put_unaligned(tp->bytes_acked, &info->tcpi_bytes_acked);
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put_unaligned(tp->bytes_received, &info->tcpi_bytes_received);
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} while (u64_stats_fetch_retry_irq(&tp->syncp, start));
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slow = lock_sock_fast(sk);
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put_unaligned(tp->bytes_acked, &info->tcpi_bytes_acked);
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put_unaligned(tp->bytes_received, &info->tcpi_bytes_received);
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info->tcpi_notsent_bytes = max_t(int, 0, tp->write_seq - tp->snd_nxt);
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unlock_sock_fast(sk, slow);
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info->tcpi_segs_out = tp->segs_out;
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info->tcpi_segs_in = tp->segs_in;
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notsent_bytes = READ_ONCE(tp->write_seq) - READ_ONCE(tp->snd_nxt);
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info->tcpi_notsent_bytes = max(0, notsent_bytes);
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info->tcpi_min_rtt = tcp_min_rtt(tp);
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info->tcpi_data_segs_in = tp->data_segs_in;
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info->tcpi_data_segs_out = tp->data_segs_out;
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@ -3351,9 +3351,7 @@ static void tcp_snd_una_update(struct tcp_sock *tp, u32 ack)
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u32 delta = ack - tp->snd_una;
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sock_owned_by_me((struct sock *)tp);
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u64_stats_update_begin_raw(&tp->syncp);
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tp->bytes_acked += delta;
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u64_stats_update_end_raw(&tp->syncp);
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tp->snd_una = ack;
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}
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@ -3363,9 +3361,7 @@ static void tcp_rcv_nxt_update(struct tcp_sock *tp, u32 seq)
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u32 delta = seq - tp->rcv_nxt;
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sock_owned_by_me((struct sock *)tp);
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u64_stats_update_begin_raw(&tp->syncp);
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tp->bytes_received += delta;
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u64_stats_update_end_raw(&tp->syncp);
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tp->rcv_nxt = seq;
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}
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