Merge branch 'vfs-6.14.poll' into vfs.fixes

Bring in the fixes for __pollwait() and waitqueue_active() interactions.

Signed-off-by: Christian Brauner <brauner@kernel.org>

2 files changed, 19 insertions, 24 deletions

diff --git a/include/linux/poll.h b/include/linux/poll.h
index d1ea4f3714a8..12bb18e8b978 100644
--- a/include/linux/poll.h
+++ b/include/linux/poll.h
@@ -25,14 +25,14 @@
 
 struct poll_table_struct;
 
-/* 
+/*
  * structures and helpers for f_op->poll implementations
  */
 typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);
 
 /*
- * Do not touch the structure directly, use the access functions
- * poll_does_not_wait() and poll_requested_events() instead.
+ * Do not touch the structure directly, use the access function
+ * poll_requested_events() instead.
  */
 typedef struct poll_table_struct {
 	poll_queue_proc _qproc;
@@ -41,18 +41,16 @@ typedef struct poll_table_struct {
 
 static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
 {
-	if (p && p->_qproc && wait_address)
+	if (p && p->_qproc) {
 		p->_qproc(filp, wait_address, p);
-}
-
-/*
- * Return true if it is guaranteed that poll will not wait. This is the case
- * if the poll() of another file descriptor in the set got an event, so there
- * is no need for waiting.
- */
-static inline bool poll_does_not_wait(const poll_table *p)
-{
-	return p == NULL || p->_qproc == NULL;
+		/*
+		 * This memory barrier is paired in the wq_has_sleeper().
+		 * See the comment above prepare_to_wait(), we need to
+		 * ensure that subsequent tests in this thread can't be
+		 * reordered with __add_wait_queue() in _qproc() paths.
+		 */
+		smp_mb();
+	}
 }
 
 /*
diff --git a/include/net/sock.h b/include/net/sock.h
index c383126f691d..691ca7695d1d 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2297,7 +2297,7 @@ static inline bool skwq_has_sleeper(struct socket_wq *wq)
 }
 
 /**
- * sock_poll_wait - place memory barrier behind the poll_wait call.
+ * sock_poll_wait - wrapper for the poll_wait call.
  * @filp:           file
  * @sock:           socket to wait on
  * @p:              poll_table
@@ -2307,15 +2307,12 @@ static inline bool skwq_has_sleeper(struct socket_wq *wq)
 static inline void sock_poll_wait(struct file *filp, struct socket *sock,
 				  poll_table *p)
 {
-	if (!poll_does_not_wait(p)) {
-		poll_wait(filp, &sock->wq.wait, 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();
-	}
+	/* Provides a barrier we need to be sure we are in sync
+	 * with the socket flags modification.
+	 *
+	 * This memory barrier is paired in the wq_has_sleeper.
+	 */
+	poll_wait(filp, &sock->wq.wait, p);
 }
 
 static inline void skb_set_hash_from_sk(struct sk_buff *skb, struct sock *sk)