From: Stefano Garzarella <sgarzare@redhat.com>
Date: Fri, 15 May 2020 16:38:05 +0000 (+0200)
Subject: io_uring: add IORING_CQ_EVENTFD_DISABLED to the CQ ring flags
X-Git-Tag: v5.10.7~2494^2~21
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=7e55a19cf6e70ce08964b46dbbfbdb07fbc995fc;p=platform%2Fkernel%2Flinux-rpi.git

io_uring: add IORING_CQ_EVENTFD_DISABLED to the CQ ring flags

This new flag should be set/clear from the application to
disable/enable eventfd notifications when a request is completed
and queued to the CQ ring.

Before this patch, notifications were always sent if an eventfd is
registered, so IORING_CQ_EVENTFD_DISABLED is not set during the
initialization.

It will be up to the application to set the flag after initialization
if no notifications are required at the beginning.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 0225069..f800b0b 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1153,6 +1153,8 @@ static inline bool io_should_trigger_evfd(struct io_ring_ctx *ctx)
 {
 	if (!ctx->cq_ev_fd)
 		return false;
+	if (READ_ONCE(ctx->rings->cq_flags) & IORING_CQ_EVENTFD_DISABLED)
+		return false;
 	if (!ctx->eventfd_async)
 		return true;
 	return io_wq_current_is_worker();
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 602bb0e..8c5775d 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -210,6 +210,13 @@ struct io_cqring_offsets {
 };
 
 /*
+ * cq_ring->flags
+ */
+
+/* disable eventfd notifications */
+#define IORING_CQ_EVENTFD_DISABLED	(1U << 0)
+
+/*
  * io_uring_enter(2) flags
  */
 #define IORING_ENTER_GETEVENTS	(1U << 0)