io_uring/zcrx: remove sync refill uapi

There is a better way to handle the problem IORING_REGISTER_ZCRX_REFILL
solves. The uapi can also be slightly adjusted to accommodate future
extensions. Remove the feature for now, it'll be reworked for the next
release.

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

Author: isilence

include/uapi/linux/io_uring.h

@@ -689,9 +689,6 @@ enum io_uring_register_op {
 	/* query various aspects of io_uring, see linux/io_uring/query.h */
 	IORING_REGISTER_QUERY			= 35,
 
-	/* return zcrx buffers back into circulation */
-	IORING_REGISTER_ZCRX_REFILL		= 36,
-
 	/* this goes last */
 	IORING_REGISTER_LAST,
 
@@ -1073,15 +1070,6 @@ struct io_uring_zcrx_ifq_reg {
 	__u64	__resv[3];
 };
 
-struct io_uring_zcrx_sync_refill {
-	__u32		zcrx_id;
-	/* the number of entries to return */
-	__u32		nr_entries;
-	/* pointer to an array of struct io_uring_zcrx_rqe */
-	__u64		rqes;
-	__u64		__resv[2];
-};
-
 #ifdef __cplusplus
 }
 #endif

io_uring/register.c

@@ -827,9 +827,6 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
 	case IORING_REGISTER_QUERY:
 		ret = io_query(ctx, arg, nr_args);
 		break;
-	case IORING_REGISTER_ZCRX_REFILL:
-		ret = io_zcrx_return_bufs(ctx, arg, nr_args);
-		break;
 	default:
 		ret = -EINVAL;
 		break;

io_uring/zcrx.c

@@ -928,74 +928,6 @@ static const struct memory_provider_ops io_uring_pp_zc_ops = {
 	.uninstall		= io_pp_uninstall,
 };
 
-#define IO_ZCRX_MAX_SYS_REFILL_BUFS		(1 << 16)
-#define IO_ZCRX_SYS_REFILL_BATCH		32
-
-static void io_return_buffers(struct io_zcrx_ifq *ifq,
-			      struct io_uring_zcrx_rqe *rqes, unsigned nr)
-{
-	int i;
-
-	for (i = 0; i < nr; i++) {
-		struct net_iov *niov;
-		netmem_ref netmem;
-
-		if (!io_parse_rqe(&rqes[i], ifq, &niov))
-			continue;
-
-		scoped_guard(spinlock_bh, &ifq->rq_lock) {
-			if (!io_zcrx_put_niov_uref(niov))
-				continue;
-		}
-
-		netmem = net_iov_to_netmem(niov);
-		if (!page_pool_unref_and_test(netmem))
-			continue;
-		io_zcrx_return_niov(niov);
-	}
-}
-
-int io_zcrx_return_bufs(struct io_ring_ctx *ctx,
-			void __user *arg, unsigned nr_arg)
-{
-	struct io_uring_zcrx_rqe rqes[IO_ZCRX_SYS_REFILL_BATCH];
-	struct io_uring_zcrx_rqe __user *user_rqes;
-	struct io_uring_zcrx_sync_refill zr;
-	struct io_zcrx_ifq *ifq;
-	unsigned nr, i;
-
-	if (nr_arg)
-		return -EINVAL;
-	if (copy_from_user(&zr, arg, sizeof(zr)))
-		return -EFAULT;
-	if (!zr.nr_entries || zr.nr_entries > IO_ZCRX_MAX_SYS_REFILL_BUFS)
-		return -EINVAL;
-	if (!mem_is_zero(&zr.__resv, sizeof(zr.__resv)))
-		return -EINVAL;
-
-	ifq = xa_load(&ctx->zcrx_ctxs, zr.zcrx_id);
-	if (!ifq)
-		return -EINVAL;
-	nr = zr.nr_entries;
-	user_rqes = u64_to_user_ptr(zr.rqes);
-
-	for (i = 0; i < nr;) {
-		unsigned batch = min(nr - i, IO_ZCRX_SYS_REFILL_BATCH);
-		size_t size = batch * sizeof(rqes[0]);
-
-		if (copy_from_user(rqes, user_rqes + i, size))
-			return i ? i : -EFAULT;
-		io_return_buffers(ifq, rqes, batch);
-
-		i += batch;
-
-		if (fatal_signal_pending(current))
-			return i;
-		cond_resched();
-	}
-	return nr;
-}
-
 static bool io_zcrx_queue_cqe(struct io_kiocb *req, struct net_iov *niov,
 			      struct io_zcrx_ifq *ifq, int off, int len)
 {

io_uring/zcrx.h

@@ -63,8 +63,6 @@ struct io_zcrx_ifq {
 };
 
 #if defined(CONFIG_IO_URING_ZCRX)
-int io_zcrx_return_bufs(struct io_ring_ctx *ctx,
-			void __user *arg, unsigned nr_arg);
 int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
 			 struct io_uring_zcrx_ifq_reg __user *arg);
 void io_unregister_zcrx_ifqs(struct io_ring_ctx *ctx);
@@ -97,11 +95,6 @@ static inline struct io_mapped_region *io_zcrx_get_region(struct io_ring_ctx *ct
 {
 	return NULL;
 }
-static inline int io_zcrx_return_bufs(struct io_ring_ctx *ctx,
-				      void __user *arg, unsigned nr_arg)
-{
-	return -EOPNOTSUPP;
-}
 #endif
 
 int io_recvzc(struct io_kiocb *req, unsigned int issue_flags);