[PATCH 7/9] io_uring/poll: pull ownership handling into poll.h

[Jens Axboe <axboe@kernel.dk>]

In preparation for using it from somewhere else. Rather than try and
duplicate the functionality, just make it generically available to
io_uring opcodes.

Note: would have to be used carefully, cannot be used by opcodes that
can trigger poll logic.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 io_uring/poll.c | 30 +-----------------------------
 io_uring/poll.h | 31 +++++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 29 deletions(-)

diff --git a/io_uring/poll.c b/io_uring/poll.c
index bb1c0cd4f809..5e44ac562491 100644
--- a/io_uring/poll.c
+++ b/io_uring/poll.c
@@ -41,16 +41,6 @@ struct io_poll_table {
 	__poll_t result_mask;
 };
 
-#define IO_POLL_CANCEL_FLAG	BIT(31)
-#define IO_POLL_RETRY_FLAG	BIT(30)
-#define IO_POLL_REF_MASK	GENMASK(29, 0)
-
-/*
- * We usually have 1-2 refs taken, 128 is more than enough and we want to
- * maximise the margin between this amount and the moment when it overflows.
- */
-#define IO_POLL_REF_BIAS	128
-
 #define IO_WQE_F_DOUBLE		1
 
 static int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
@@ -70,7 +60,7 @@ static inline bool wqe_is_double(struct wait_queue_entry *wqe)
 	return priv & IO_WQE_F_DOUBLE;
 }
 
-static bool io_poll_get_ownership_slowpath(struct io_kiocb *req)
+bool io_poll_get_ownership_slowpath(struct io_kiocb *req)
 {
 	int v;
 
@@ -85,24 +75,6 @@ static bool io_poll_get_ownership_slowpath(struct io_kiocb *req)
 	return !(atomic_fetch_inc(&req->poll_refs) & IO_POLL_REF_MASK);
 }
 
-/*
- * If refs part of ->poll_refs (see IO_POLL_REF_MASK) is 0, it's free. We can
- * bump it and acquire ownership. It's disallowed to modify requests while not
- * owning it, that prevents from races for enqueueing task_work's and b/w
- * arming poll and wakeups.
- */
-static inline bool io_poll_get_ownership(struct io_kiocb *req)
-{
-	if (unlikely(atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS))
-		return io_poll_get_ownership_slowpath(req);
-	return !(atomic_fetch_inc(&req->poll_refs) & IO_POLL_REF_MASK);
-}
-
-static void io_poll_mark_cancelled(struct io_kiocb *req)
-{
-	atomic_or(IO_POLL_CANCEL_FLAG, &req->poll_refs);
-}
-
 static struct io_poll *io_poll_get_double(struct io_kiocb *req)
 {
 	/* pure poll stashes this in ->async_data, poll driven retry elsewhere */
diff --git a/io_uring/poll.h b/io_uring/poll.h
index 04ede93113dc..2f416cd3be13 100644
--- a/io_uring/poll.h
+++ b/io_uring/poll.h
@@ -21,6 +21,18 @@ struct async_poll {
 	struct io_poll		*double_poll;
 };
 
+#define IO_POLL_CANCEL_FLAG	BIT(31)
+#define IO_POLL_RETRY_FLAG	BIT(30)
+#define IO_POLL_REF_MASK	GENMASK(29, 0)
+
+bool io_poll_get_ownership_slowpath(struct io_kiocb *req);
+
+/*
+ * We usually have 1-2 refs taken, 128 is more than enough and we want to
+ * maximise the margin between this amount and the moment when it overflows.
+ */
+#define IO_POLL_REF_BIAS	128
+
 /*
  * Must only be called inside issue_flags & IO_URING_F_MULTISHOT, or
  * potentially other cases where we already "own" this poll request.
@@ -30,6 +42,25 @@ static inline void io_poll_multishot_retry(struct io_kiocb *req)
 	atomic_inc(&req->poll_refs);
 }
 
+/*
+ * If refs part of ->poll_refs (see IO_POLL_REF_MASK) is 0, it's free. We can
+ * bump it and acquire ownership. It's disallowed to modify requests while not
+ * owning it, that prevents from races for enqueueing task_work's and b/w
+ * arming poll and wakeups.
+ */
+static inline bool io_poll_get_ownership(struct io_kiocb *req)
+{
+	if (unlikely(atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS))
+		return io_poll_get_ownership_slowpath(req);
+	return !(atomic_fetch_inc(&req->poll_refs) & IO_POLL_REF_MASK);
+}
+
+static inline void io_poll_mark_cancelled(struct io_kiocb *req)
+{
+	atomic_or(IO_POLL_CANCEL_FLAG, &req->poll_refs);
+}
+
+
 int io_poll_add_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
 int io_poll_add(struct io_kiocb *req, unsigned int issue_flags);
 
-- 
2.47.2