io_uring/netcmd: add tx timestamping cmd support

Add a new socket command which returns tx time stamps to the user. It
provide an alternative to the existing error queue recvmsg interface.
The command works in a polled multishot mode, which means io_uring will
poll the socket and keep posting timestamps until the request is
cancelled or fails in any other way (e.g. with no space in the CQ). It
reuses the net infra and grabs timestamps from the socket's error queue.

The command requires IORING_SETUP_CQE32. All non-final CQEs (marked with
IORING_CQE_F_MORE) have cqe->res set to the tskey, and the upper 16 bits
of cqe->flags keep tstype (i.e. offset by IORING_CQE_BUFFER_SHIFT). The
timevalue is store in the upper part of the extended CQE. The final
completion won't have IORING_CQE_F_MORE and will have cqe->res storing
0/error.

Suggested-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/92ee66e6b33b8de062a977843d825f58f21ecd37.1750065793.git.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 8c3d43caab02d113acfc47865ed585ab8b362a88..85600ad0ac082e39595a4af75ca6f441268c2cd7 100644 (file)
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -969,6 +969,22 @@ enum io_uring_socket_op {
        SOCKET_URING_OP_SIOCOUTQ,
        SOCKET_URING_OP_GETSOCKOPT,
        SOCKET_URING_OP_SETSOCKOPT,
+       SOCKET_URING_OP_TX_TIMESTAMP,
+};
+
+/*
+ * SOCKET_URING_OP_TX_TIMESTAMP definitions
+ */
+
+#define IORING_TIMESTAMP_HW_SHIFT      16
+/* The cqe->flags bit from which the timestamp type is stored */
+#define IORING_TIMESTAMP_TYPE_SHIFT    (IORING_TIMESTAMP_HW_SHIFT + 1)
+/* The cqe->flags flag signifying whether it's a hardware timestamp */
+#define IORING_CQE_F_TSTAMP_HW         ((__u32)1 << IORING_TIMESTAMP_HW_SHIFT);
+
+struct io_timespec {
+       __u64           tv_sec;
+       __u64           tv_nsec;
 };
 
 /* Zero copy receive refill queue entry */

diff --git a/io_uring/cmd_net.c b/io_uring/cmd_net.c
index e99170c7d41add2a37280384f8c2692ca67b9a34..3866fe6ff541d5677396746df5d66512cd281572 100644 (file)
--- a/io_uring/cmd_net.c
+++ b/io_uring/cmd_net.c
@@ -1,5 +1,6 @@
 #include <asm/ioctls.h>
 #include <linux/io_uring/net.h>
+#include <linux/errqueue.h>
 #include <net/sock.h>
 
 #include "uring_cmd.h"
@@ -51,6 +52,85 @@ static inline int io_uring_cmd_setsockopt(struct socket *sock,
                                  optlen);
 }
 
+static bool io_process_timestamp_skb(struct io_uring_cmd *cmd, struct sock *sk,
+                                    struct sk_buff *skb, unsigned issue_flags)
+{
+       struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
+       struct io_uring_cqe cqe[2];
+       struct io_timespec *iots;
+       struct timespec64 ts;
+       u32 tstype, tskey;
+       int ret;
+
+       BUILD_BUG_ON(sizeof(struct io_uring_cqe) != sizeof(struct io_timespec));
+
+       ret = skb_get_tx_timestamp(skb, sk, &ts);
+       if (ret < 0)
+               return false;
+
+       tskey = serr->ee.ee_data;
+       tstype = serr->ee.ee_info;
+
+       cqe->user_data = 0;
+       cqe->res = tskey;
+       cqe->flags = IORING_CQE_F_MORE;
+       cqe->flags |= tstype << IORING_TIMESTAMP_TYPE_SHIFT;
+       if (ret == SOF_TIMESTAMPING_TX_HARDWARE)
+               cqe->flags |= IORING_CQE_F_TSTAMP_HW;
+
+       iots = (struct io_timespec *)&cqe[1];
+       iots->tv_sec = ts.tv_sec;
+       iots->tv_nsec = ts.tv_nsec;
+       return io_uring_cmd_post_mshot_cqe32(cmd, issue_flags, cqe);
+}
+
+static int io_uring_cmd_timestamp(struct socket *sock,
+                                 struct io_uring_cmd *cmd,
+                                 unsigned int issue_flags)
+{
+       struct sock *sk = sock->sk;
+       struct sk_buff_head *q = &sk->sk_error_queue;
+       struct sk_buff *skb, *tmp;
+       struct sk_buff_head list;
+       int ret;
+
+       if (!(issue_flags & IO_URING_F_CQE32))
+               return -EINVAL;
+       ret = io_cmd_poll_multishot(cmd, issue_flags, EPOLLERR);
+       if (unlikely(ret))
+               return ret;
+
+       if (skb_queue_empty_lockless(q))
+               return -EAGAIN;
+       __skb_queue_head_init(&list);
+
+       scoped_guard(spinlock_irq, &q->lock) {
+               skb_queue_walk_safe(q, skb, tmp) {
+                       /* don't support skbs with payload */
+                       if (!skb_has_tx_timestamp(skb, sk) || skb->len)
+                               continue;
+                       __skb_unlink(skb, q);
+                       __skb_queue_tail(&list, skb);
+               }
+       }
+
+       while (1) {
+               skb = skb_peek(&list);
+               if (!skb)
+                       break;
+               if (!io_process_timestamp_skb(cmd, sk, skb, issue_flags))
+                       break;
+               __skb_dequeue(&list);
+               consume_skb(skb);
+       }
+
+       if (!unlikely(skb_queue_empty(&list))) {
+               scoped_guard(spinlock_irqsave, &q->lock)
+                       skb_queue_splice(q, &list);
+       }
+       return -EAGAIN;
+}
+
 int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
 {
        struct socket *sock = cmd->file->private_data;
@@ -76,6 +156,8 @@ int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
                return io_uring_cmd_getsockopt(sock, cmd, issue_flags);
        case SOCKET_URING_OP_SETSOCKOPT:
                return io_uring_cmd_setsockopt(sock, cmd, issue_flags);
+       case SOCKET_URING_OP_TX_TIMESTAMP:
+               return io_uring_cmd_timestamp(sock, cmd, issue_flags);
        default:
                return -EOPNOTSUPP;
        }