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;
 }