2 files changed, 50 insertions, 0 deletions

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 468f9da472b2..2a46de56d05c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -241,6 +241,7 @@ struct io_ring_ctx {
                 unsigned                cq_mask;
                 struct wait_queue_head  cq_wait;
                 struct fasync_struct    *cq_fasync;
+                struct eventfd_ctx      *cq_ev_fd;
         } ____cacheline_aligned_in_smp;
 
         /*
@@ -516,6 +517,8 @@ static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
                 wake_up(&ctx->wait);
         if (waitqueue_active(&ctx->sqo_wait))
                 wake_up(&ctx->sqo_wait);
+        if (ctx->cq_ev_fd)
+                eventfd_signal(ctx->cq_ev_fd, 1);
 }
 
 static void io_cqring_add_event(struct io_ring_ctx *ctx, u64 user_data,
@@ -2757,6 +2760,38 @@ err:
         return ret;
 }
 
+static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg)
+{
+        __s32 __user *fds = arg;
+        int fd;
+
+        if (ctx->cq_ev_fd)
+                return -EBUSY;
+
+        if (copy_from_user(&fd, fds, sizeof(*fds)))
+                return -EFAULT;
+
+        ctx->cq_ev_fd = eventfd_ctx_fdget(fd);
+        if (IS_ERR(ctx->cq_ev_fd)) {
+                int ret = PTR_ERR(ctx->cq_ev_fd);
+                ctx->cq_ev_fd = NULL;
+                return ret;
+        }
+
+        return 0;
+}
+
+static int io_eventfd_unregister(struct io_ring_ctx *ctx)
+{
+        if (ctx->cq_ev_fd) {
+                eventfd_ctx_put(ctx->cq_ev_fd);
+                ctx->cq_ev_fd = NULL;
+                return 0;
+        }
+
+        return -ENXIO;
+}
+
 static void io_ring_ctx_free(struct io_ring_ctx *ctx)
 {
         io_finish_async(ctx);
@@ -2766,6 +2801,7 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
         io_iopoll_reap_events(ctx);
         io_sqe_buffer_unregister(ctx);
         io_sqe_files_unregister(ctx);
+        io_eventfd_unregister(ctx);
 
 #if defined(CONFIG_UNIX)
         if (ctx->ring_sock)
@@ -3179,6 +3215,18 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
                         break;
                 ret = io_sqe_files_unregister(ctx);
                 break;
+        case IORING_REGISTER_EVENTFD:
+                ret = -EINVAL;
+                if (nr_args != 1)
+                        break;
+                ret = io_eventfd_register(ctx, arg);
+                break;
+        case IORING_UNREGISTER_EVENTFD:
+                ret = -EINVAL;
+                if (arg || nr_args)
+                        break;
+                ret = io_eventfd_unregister(ctx);
+                break;
         default:
                 ret = -EINVAL;
                 break;
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index e707a17c6908..a0c460025036 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -136,5 +136,7 @@ struct io_uring_params {
 #define IORING_UNREGISTER_BUFFERS       1
 #define IORING_REGISTER_FILES           2
 #define IORING_UNREGISTER_FILES         3
+#define IORING_REGISTER_EVENTFD         4
+#define IORING_UNREGISTER_EVENTFD       5
 
 #endif