This patch adds the new IORING_CQ_EVENTFD_DISABLED flag. It can be
used to disable/enable notifications from the kernel when a
request is completed and queued to the CQ ring.
We also add two helpers function to check if the notifications are
enabled and to enable/disable them.
If the kernel doesn't provide CQ ring flags, the notifications are
always enabled if an eventfd is registered.
Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
---
src/include/liburing.h | 30 ++++++++++++++++++++++++++++++
src/include/liburing/io_uring.h | 7 +++++++
2 files changed, 37 insertions(+)
diff --git a/src/include/liburing.h b/src/include/liburing.h
index ea596f6..fe03547 100644
--- a/src/include/liburing.h
+++ b/src/include/liburing.h
@@ -9,7 +9,9 @@ extern "C" {
#include <sys/socket.h>
#include <sys/uio.h>
#include <sys/stat.h>
+#include <errno.h>
#include <signal.h>
+#include <stdbool.h>
#include <inttypes.h>
#include <time.h>
#include "liburing/compat.h"
@@ -445,6 +447,34 @@ static inline unsigned io_uring_cq_ready(struct io_uring *ring)
return io_uring_smp_load_acquire(ring->cq.ktail) - *ring->cq.khead;
}
+static inline int io_uring_cq_eventfd_enable(struct io_uring *ring,
+ bool enabled)
+{
+ uint32_t flags;
+
+ if (!ring->cq.kflags)
+ return -ENOTSUP;
+
+ flags = *ring->cq.kflags;
+
+ if (enabled)
+ flags &= ~IORING_CQ_EVENTFD_DISABLED;
+ else
+ flags |= IORING_CQ_EVENTFD_DISABLED;
+
+ IO_URING_WRITE_ONCE(*ring->cq.kflags, flags);
+
+ return 0;
+}
+
+static inline bool io_uring_cq_eventfd_enabled(struct io_uring *ring)
+{
+ if (!ring->cq.kflags)
+ return true;
+
+ return !(*ring->cq.kflags & IORING_CQ_EVENTFD_DISABLED);
+}
+
static int __io_uring_peek_cqe(struct io_uring *ring, struct io_uring_cqe **cqe_ptr)
{
struct io_uring_cqe *cqe;
diff --git a/src/include/liburing/io_uring.h b/src/include/liburing/io_uring.h
index 602bb0e..8c5775d 100644
--- a/src/include/liburing/io_uring.h
+++ b/src/include/liburing/io_uring.h
@@ -209,6 +209,13 @@ struct io_cqring_offsets {
__u64 resv2;
};
+/*
+ * cq_ring->flags
+ */
+
+/* disable eventfd notifications */
+#define IORING_CQ_EVENTFD_DISABLED (1U << 0)
+
/*
* io_uring_enter(2) flags
*/
--
2.25.4
