[PATCH for-next 4/7] io_uring: do not always run task work at the start of io_uring_enter

[Dylan Yudaken <dylany@fb.com>]

It is normally better to wait for task work until after submissions. This
will allow greater batching if either work arrives in the meanwhile, or if
the submissions cause task work to be queued up.

For SQPOLL this also no longer runs task work, but this is handled inside
the SQPOLL loop anyway.

For IOPOLL io_iopoll_check will run task work anyway

Signed-off-by: Dylan Yudaken <dylany@fb.com>
---
 io_uring/io_uring.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 8cc4b28b1725..3b08369c3c60 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2990,8 +2990,6 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
 	struct fd f;
 	long ret;
 
-	io_run_task_work();
-
 	if (unlikely(flags & ~(IORING_ENTER_GETEVENTS | IORING_ENTER_SQ_WAKEUP |
 			       IORING_ENTER_SQ_WAIT | IORING_ENTER_EXT_ARG |
 			       IORING_ENTER_REGISTERED_RING)))
@@ -3060,7 +3058,11 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
 		if ((flags & IORING_ENTER_GETEVENTS) && ctx->syscall_iopoll)
 			goto iopoll_locked;
 		mutex_unlock(&ctx->uring_lock);
+		io_run_task_work();
+	} else {
+		io_run_task_work();
 	}
+
 	if (flags & IORING_ENTER_GETEVENTS) {
 		int ret2;
 		if (ctx->syscall_iopoll) {
-- 
2.30.2