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Date: Sun, 22 Mar 2015 10:22:21 -0700
From: Eric Dumazet <edumazet@...gle.com>
To: "David S. Miller" <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>,
Eric Dumazet <eric.dumazet@...il.com>,
Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 4/8] 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 <edumazet@...gle.com>
---
include/net/request_sock.h | 11 +++--------
net/core/request_sock.c | 14 +++++++-------
net/ipv4/inet_connection_sock.c | 8 ++++----
net/ipv4/inet_diag.c | 4 ++--
net/ipv4/tcp_ipv4.c | 12 ++++++------
net/ipv6/inet6_connection_sock.c | 4 ++--
6 files changed, 24 insertions(+), 29 deletions(-)
diff --git a/include/net/request_sock.h b/include/net/request_sock.h
index 8603c350fad0..fe41f3ceb008 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 cdc0ddd9ac9f..87b22c0bc08c 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 711ab143d4cb..79c0c9439fdc 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 f984b2001d0a..76322c9867d5 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 5554b8f33d41..8028ad5920a4 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 2f3bbe569e8f..6927f3fb5597 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;
}
--
2.2.0.rc0.207.ga3a616c
--
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