io_uring/zcrx: export zcrx via a file

Add an option to wrap a zcrx instance into a file and expose it to the
user space. Currently, users can't do anything meaningful with the file,
but it'll be used in a next patch to import it into another io_uring
instance. It's implemented as a new op called ZCRX_CTRL_EXPORT for the
IORING_REGISTER_ZCRX_CTRL registration opcode.

Signed-off-by: David Wei <dw@davidwei.uk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index db47fced2cc671efd2bf8df295addacc9153b5fd..4bedc0310a55550512d910400cb2d1252ab32674 100644 (file)
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -1083,6 +1083,7 @@ struct io_uring_zcrx_ifq_reg {
 
 enum zcrx_ctrl_op {
        ZCRX_CTRL_FLUSH_RQ,
+       ZCRX_CTRL_EXPORT,
 
        __ZCRX_CTRL_LAST,
 };
@@ -1091,12 +1092,20 @@ struct zcrx_ctrl_flush_rq {
        __u64           __resv[6];
 };
 
+struct zcrx_ctrl_export {
+       __u32           zcrx_fd;
+       __u32           __resv1[11];
+};
+
 struct zcrx_ctrl {
        __u32   zcrx_id;
        __u32   op; /* see enum zcrx_ctrl_op */
        __u64   __resv[2];
 
-       struct zcrx_ctrl_flush_rq       zc_flush;
+       union {
+               struct zcrx_ctrl_export         zc_export;
+               struct zcrx_ctrl_flush_rq       zc_flush;
+       };
 };
 
 #ifdef __cplusplus

diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index e60c5c00a6118aa9e07b1e8f20f4df6f4d18b206..815992aff246d5acd6acad2810d6688c13e8e1e0 100644 (file)
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -8,6 +8,7 @@
 #include <linux/netdevice.h>
 #include <linux/rtnetlink.h>
 #include <linux/skbuff_ref.h>
+#include <linux/anon_inodes.h>
 
 #include <net/page_pool/helpers.h>
 #include <net/page_pool/memory_provider.h>
@@ -586,6 +587,15 @@ static void io_zcrx_scrub(struct io_zcrx_ifq *ifq)
        }
 }
 
+static void zcrx_unregister(struct io_zcrx_ifq *ifq)
+{
+       if (refcount_dec_and_test(&ifq->user_refs)) {
+               io_close_queue(ifq);
+               io_zcrx_scrub(ifq);
+       }
+       io_put_zcrx_ifq(ifq);
+}
+
 struct io_mapped_region *io_zcrx_get_region(struct io_ring_ctx *ctx,
                                            unsigned int id)
 {
@@ -596,6 +606,55 @@ struct io_mapped_region *io_zcrx_get_region(struct io_ring_ctx *ctx,
        return ifq ? &ifq->region : NULL;
 }
 
+static int zcrx_box_release(struct inode *inode, struct file *file)
+{
+       struct io_zcrx_ifq *ifq = file->private_data;
+
+       if (WARN_ON_ONCE(!ifq))
+               return -EFAULT;
+       zcrx_unregister(ifq);
+       return 0;
+}
+
+static const struct file_operations zcrx_box_fops = {
+       .owner          = THIS_MODULE,
+       .release        = zcrx_box_release,
+};
+
+static int zcrx_export(struct io_ring_ctx *ctx, struct io_zcrx_ifq *ifq,
+                      struct zcrx_ctrl *ctrl, void __user *arg)
+{
+       struct zcrx_ctrl_export *ce = &ctrl->zc_export;
+       struct file *file;
+       int fd = -1;
+
+       if (!mem_is_zero(ce, sizeof(*ce)))
+               return -EINVAL;
+       fd = get_unused_fd_flags(O_CLOEXEC);
+       if (fd < 0)
+               return fd;
+
+       ce->zcrx_fd = fd;
+       if (copy_to_user(arg, ctrl, sizeof(*ctrl))) {
+               put_unused_fd(fd);
+               return -EFAULT;
+       }
+
+       refcount_inc(&ifq->refs);
+       refcount_inc(&ifq->user_refs);
+
+       file = anon_inode_create_getfile("[zcrx]", &zcrx_box_fops,
+                                        ifq, O_CLOEXEC, NULL);
+       if (IS_ERR(file)) {
+               put_unused_fd(fd);
+               zcrx_unregister(ifq);
+               return PTR_ERR(file);
+       }
+
+       fd_install(fd, file);
+       return 0;
+}
+
 int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
                          struct io_uring_zcrx_ifq_reg __user *arg)
 {
@@ -742,12 +801,7 @@ void io_unregister_zcrx_ifqs(struct io_ring_ctx *ctx)
                }
                if (!ifq)
                        break;
-
-               if (refcount_dec_and_test(&ifq->user_refs)) {
-                       io_close_queue(ifq);
-                       io_zcrx_scrub(ifq);
-               }
-               io_put_zcrx_ifq(ifq);
+               zcrx_unregister(ifq);
        }
 
        xa_destroy(&ctx->zcrx_ctxs);
@@ -1028,6 +1082,8 @@ int io_zcrx_ctrl(struct io_ring_ctx *ctx, void __user *arg, unsigned nr_args)
        switch (ctrl.op) {
        case ZCRX_CTRL_FLUSH_RQ:
                return zcrx_flush_rq(ctx, zcrx, &ctrl);
+       case ZCRX_CTRL_EXPORT:
+               return zcrx_export(ctx, zcrx, &ctrl, arg);
        }
 
        return -EOPNOTSUPP;