+/**
+ * sk_wmem_alloc_get - returns write allocations
+ * @sk: socket
+ *
+ * Returns sk_wmem_alloc minus initial offset of one
+ */
+static inline int sk_wmem_alloc_get(const struct sock *sk)
+{
+ return atomic_read(&sk->sk_wmem_alloc) - 1;
+}
+
+/**
+ * sk_rmem_alloc_get - returns read allocations
+ * @sk: socket
+ *
+ * Returns sk_rmem_alloc
+ */
+static inline int sk_rmem_alloc_get(const struct sock *sk)
+{
+ return atomic_read(&sk->sk_rmem_alloc);
+}
+
+/**
+ * sk_has_allocations - check if allocations are outstanding
+ * @sk: socket
+ *
+ * Returns true if socket has write or read allocations
+ */
+static inline int sk_has_allocations(const struct sock *sk)
+{
+ return sk_wmem_alloc_get(sk) || sk_rmem_alloc_get(sk);
+}
+
+/**
+ * wq_has_sleeper - check if there are any waiting processes
+ * @sk: struct socket_wq
+ *
+ * Returns true if socket_wq has waiting processes
+ *
+ * The purpose of the wq_has_sleeper and sock_poll_wait is to wrap the memory
+ * barrier call. They were added due to the race found within the tcp code.
+ *
+ * Consider following tcp code paths:
+ *
+ * CPU1 CPU2
+ *
+ * sys_select receive packet
+ * ... ...
+ * __add_wait_queue update tp->rcv_nxt
+ * ... ...
+ * tp->rcv_nxt check sock_def_readable
+ * ... {
+ * schedule rcu_read_lock();
+ * wq = rcu_dereference(sk->sk_wq);
+ * if (wq && waitqueue_active(&wq->wait))
+ * wake_up_interruptible(&wq->wait)
+ * ...
+ * }
+ *
+ * The race for tcp fires when the __add_wait_queue changes done by CPU1 stay
+ * in its cache, and so does the tp->rcv_nxt update on CPU2 side. The CPU1
+ * could then endup calling schedule and sleep forever if there are no more
+ * data on the socket.
+ *
+ */
+static inline bool wq_has_sleeper(struct socket_wq *wq)
+{
+
+ /*
+ * We need to be sure we are in sync with the
+ * add_wait_queue modifications to the wait queue.
+ *
+ * This memory barrier is paired in the sock_poll_wait.
+ */
+ smp_mb();
+ return wq && waitqueue_active(&wq->wait);
+}
+
+/**
+ * sock_poll_wait - place memory barrier behind the poll_wait call.
+ * @filp: file
+ * @wait_address: socket wait queue
+ * @p: poll_table
+ *
+ * See the comments in the wq_has_sleeper function.
+ */
+static inline void sock_poll_wait(struct file *filp,
+ wait_queue_head_t *wait_address, poll_table *p)
+{
+ if (p && wait_address) {
+ poll_wait(filp, wait_address, p);
+ /*
+ * We need to be sure we are in sync with the
+ * socket flags modification.
+ *
+ * This memory barrier is paired in the wq_has_sleeper.
+ */
+ smp_mb();
+ }
+}
+