From b282705336e03fc7b9377a278939594870a40f96 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 22 Mar 2015 10:22:21 -0700 Subject: net: convert syn_wait_lock to a spinlock This is a low hanging fruit, as we'll get rid of syn_wait_lock eventually. We hold syn_wait_lock for such small sections, that it makes no sense to use a read/write lock. A spin lock is simply faster. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller diff --git a/include/net/request_sock.h b/include/net/request_sock.h index 8603c35..fe41f3c 100644 --- a/include/net/request_sock.h +++ b/include/net/request_sock.h @@ -173,11 +173,6 @@ struct fastopen_queue { * %syn_wait_lock is necessary only to avoid proc interface having to grab the main * lock sock while browsing the listening hash (otherwise it's deadlock prone). * - * This lock is acquired in read mode only from listening_get_next() seq_file - * op and it's acquired in write mode _only_ from code that is actively - * changing rskq_accept_head. All readers that are holding the master sock lock - * don't need to grab this lock in read mode too as rskq_accept_head. writes - * are always protected from the main sock lock. */ struct request_sock_queue { struct request_sock *rskq_accept_head; @@ -192,7 +187,7 @@ struct request_sock_queue { */ /* temporary alignment, our goal is to get rid of this lock */ - rwlock_t syn_wait_lock ____cacheline_aligned_in_smp; + spinlock_t syn_wait_lock ____cacheline_aligned_in_smp; }; int reqsk_queue_alloc(struct request_sock_queue *queue, @@ -223,14 +218,14 @@ static inline void reqsk_queue_unlink(struct request_sock_queue *queue, struct listen_sock *lopt = queue->listen_opt; struct request_sock **prev; - write_lock(&queue->syn_wait_lock); + spin_lock(&queue->syn_wait_lock); prev = &lopt->syn_table[req->rsk_hash]; while (*prev != req) prev = &(*prev)->dl_next; *prev = req->dl_next; - write_unlock(&queue->syn_wait_lock); + spin_unlock(&queue->syn_wait_lock); if (del_timer(&req->rsk_timer)) reqsk_put(req); } diff --git a/net/core/request_sock.c b/net/core/request_sock.c index cdc0ddd..87b22c0 100644 --- a/net/core/request_sock.c +++ b/net/core/request_sock.c @@ -58,14 +58,14 @@ int reqsk_queue_alloc(struct request_sock_queue *queue, return -ENOMEM; get_random_bytes(&lopt->hash_rnd, sizeof(lopt->hash_rnd)); - rwlock_init(&queue->syn_wait_lock); + spin_lock_init(&queue->syn_wait_lock); queue->rskq_accept_head = NULL; lopt->nr_table_entries = nr_table_entries; lopt->max_qlen_log = ilog2(nr_table_entries); - write_lock_bh(&queue->syn_wait_lock); + spin_lock_bh(&queue->syn_wait_lock); queue->listen_opt = lopt; - write_unlock_bh(&queue->syn_wait_lock); + spin_unlock_bh(&queue->syn_wait_lock); return 0; } @@ -81,10 +81,10 @@ static inline struct listen_sock *reqsk_queue_yank_listen_sk( { struct listen_sock *lopt; - write_lock_bh(&queue->syn_wait_lock); + spin_lock_bh(&queue->syn_wait_lock); lopt = queue->listen_opt; queue->listen_opt = NULL; - write_unlock_bh(&queue->syn_wait_lock); + spin_unlock_bh(&queue->syn_wait_lock); return lopt; } @@ -100,7 +100,7 @@ void reqsk_queue_destroy(struct request_sock_queue *queue) for (i = 0; i < lopt->nr_table_entries; i++) { struct request_sock *req; - write_lock_bh(&queue->syn_wait_lock); + spin_lock_bh(&queue->syn_wait_lock); while ((req = lopt->syn_table[i]) != NULL) { lopt->syn_table[i] = req->dl_next; atomic_inc(&lopt->qlen_dec); @@ -108,7 +108,7 @@ void reqsk_queue_destroy(struct request_sock_queue *queue) reqsk_put(req); reqsk_put(req); } - write_unlock_bh(&queue->syn_wait_lock); + spin_unlock_bh(&queue->syn_wait_lock); } } diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index 711ab143..79c0c94 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -495,7 +495,7 @@ struct request_sock *inet_csk_search_req(struct sock *sk, u32 hash = inet_synq_hash(raddr, rport, lopt->hash_rnd, lopt->nr_table_entries); - write_lock(&icsk->icsk_accept_queue.syn_wait_lock); + spin_lock(&icsk->icsk_accept_queue.syn_wait_lock); for (req = lopt->syn_table[hash]; req != NULL; req = req->dl_next) { const struct inet_request_sock *ireq = inet_rsk(req); @@ -508,7 +508,7 @@ struct request_sock *inet_csk_search_req(struct sock *sk, break; } } - write_unlock(&icsk->icsk_accept_queue.syn_wait_lock); + spin_unlock(&icsk->icsk_accept_queue.syn_wait_lock); return req; } @@ -650,10 +650,10 @@ void reqsk_queue_hash_req(struct request_sock_queue *queue, setup_timer(&req->rsk_timer, reqsk_timer_handler, (unsigned long)req); req->rsk_hash = hash; - write_lock(&queue->syn_wait_lock); + spin_lock(&queue->syn_wait_lock); req->dl_next = lopt->syn_table[hash]; lopt->syn_table[hash] = req; - write_unlock(&queue->syn_wait_lock); + spin_unlock(&queue->syn_wait_lock); mod_timer_pinned(&req->rsk_timer, jiffies + timeout); } diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c index f984b20..76322c9 100644 --- a/net/ipv4/inet_diag.c +++ b/net/ipv4/inet_diag.c @@ -728,7 +728,7 @@ static int inet_diag_dump_reqs(struct sk_buff *skb, struct sock *sk, entry.family = sk->sk_family; - read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock); + spin_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock); lopt = icsk->icsk_accept_queue.listen_opt; if (!lopt || !listen_sock_qlen(lopt)) @@ -776,7 +776,7 @@ static int inet_diag_dump_reqs(struct sk_buff *skb, struct sock *sk, } out: - read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); + spin_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); return err; } diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 5554b8f..8028ad5 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1909,13 +1909,13 @@ get_req: } sk = sk_nulls_next(st->syn_wait_sk); st->state = TCP_SEQ_STATE_LISTENING; - read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); + spin_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); } else { icsk = inet_csk(sk); - read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock); + spin_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock); if (reqsk_queue_len(&icsk->icsk_accept_queue)) goto start_req; - read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); + spin_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); sk = sk_nulls_next(sk); } get_sk: @@ -1927,7 +1927,7 @@ get_sk: goto out; } icsk = inet_csk(sk); - read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock); + spin_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock); if (reqsk_queue_len(&icsk->icsk_accept_queue)) { start_req: st->uid = sock_i_uid(sk); @@ -1936,7 +1936,7 @@ start_req: st->sbucket = 0; goto get_req; } - read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); + spin_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); } spin_unlock_bh(&ilb->lock); st->offset = 0; @@ -2155,7 +2155,7 @@ static void tcp_seq_stop(struct seq_file *seq, void *v) case TCP_SEQ_STATE_OPENREQ: if (v) { struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk); - read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); + spin_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); } case TCP_SEQ_STATE_LISTENING: if (v != SEQ_START_TOKEN) diff --git a/net/ipv6/inet6_connection_sock.c b/net/ipv6/inet6_connection_sock.c index 2f3bbe5..6927f3f 100644 --- a/net/ipv6/inet6_connection_sock.c +++ b/net/ipv6/inet6_connection_sock.c @@ -124,7 +124,7 @@ struct request_sock *inet6_csk_search_req(struct sock *sk, u32 hash = inet6_synq_hash(raddr, rport, lopt->hash_rnd, lopt->nr_table_entries); - write_lock(&icsk->icsk_accept_queue.syn_wait_lock); + spin_lock(&icsk->icsk_accept_queue.syn_wait_lock); for (req = lopt->syn_table[hash]; req != NULL; req = req->dl_next) { const struct inet_request_sock *ireq = inet_rsk(req); @@ -138,7 +138,7 @@ struct request_sock *inet6_csk_search_req(struct sock *sk, break; } } - write_unlock(&icsk->icsk_accept_queue.syn_wait_lock); + spin_unlock(&icsk->icsk_accept_queue.syn_wait_lock); return req; } -- cgit v0.10.2