Re: [PATCH] net/ceph/messenger: print TCP connect error

[Ilya Dryomov]

On Thu, Sep 10, 2026 at 2:39 PM Max Kellermann <max.kellermann@xxxxxxxxx> wrote:
>
> A non-blocking connect() usually returns `-EINPROGRESS` and fails
> later, asynchronously; the actual error is then only visible as
> `sk->sk_err` in the sk_state_change() callback and was silently
> dropped.  All the user got was:
>
>  libceph: mon4 (1)192.168.1.42:6789 socket closed (con state V1_BANNER)
>
> Save the error in the new field `ceph_connection.error_code` and let
> con_fault() print it next to `error_msg`:

Hi Max,

I wonder if saving the error that way is actually needed.  Can
con_fault() just reap it with sock_error() at the time it runs?

Thanks,

                Ilya

>
>  libceph: mon4 (1)192.168.1.42:6789 socket closed (con state V1_BANNER) (-ECONNREFUSED)
>
> Signed-off-by: Max Kellermann <max.kellermann@xxxxxxxxx>
> ---
>  include/linux/ceph/messenger.h |  1 +
>  net/ceph/messenger.c           | 23 ++++++++++++++++++-----
>  2 files changed, 19 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/ceph/messenger.h b/include/linux/ceph/messenger.h
> index 6aa4c6478c9f..f3aa977d7886 100644
> --- a/include/linux/ceph/messenger.h
> +++ b/include/linux/ceph/messenger.h
> @@ -482,6 +482,7 @@ struct ceph_connection {
>
>         unsigned long flags;  /* CEPH_CON_F_* */
>         const char *error_msg;  /* error message, if any */
> +       int error_code;  /* errno (negative), if any */
>
>         struct ceph_entity_name peer_name; /* peer name */
>         struct ceph_entity_addr peer_addr; /* peer address */
> diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
> index 212e7797f9e4..f989e043686d 100644
> --- a/net/ceph/messenger.c
> +++ b/net/ceph/messenger.c
> @@ -398,6 +398,7 @@ static void ceph_sock_state_change(struct sock *sk)
>         case TCP_CLOSE_WAIT:
>                 dout("%s TCP_CLOSE_WAIT\n", __func__);
>                 con_sock_state_closing(con);
> +               WRITE_ONCE(con->error_code, -READ_ONCE(sk->sk_err));
>                 ceph_con_flag_set(con, CEPH_CON_F_SOCK_CLOSED);
>                 queue_con(con);
>                 break;
> @@ -448,8 +449,10 @@ int ceph_tcp_connect(struct ceph_connection *con)
>         ret = sock_create_kern(read_pnet(&con->msgr->net), ss.ss_family,
>                                SOCK_STREAM, IPPROTO_TCP, &sock);
>         memalloc_noio_restore(noio_flag);
> -       if (ret)
> +       if (ret) {
> +               con->error_code = ret;
>                 return ret;
> +       }
>         sock->sk->sk_allocation = GFP_NOFS;
>         sock->sk->sk_use_task_frag = false;
>
> @@ -467,9 +470,9 @@ int ceph_tcp_connect(struct ceph_connection *con)
>                      ceph_pr_addr(&con->peer_addr),
>                      sock->sk->sk_state);
>         } else if (ret < 0) {
> -               pr_err("connect %s error %d\n",
> -                      ceph_pr_addr(&con->peer_addr), ret);
>                 sock_release(sock);
> +               /* reported by con_fault() */
> +               con->error_code = ret;
>                 return ret;
>         }
>
> @@ -501,6 +504,7 @@ int ceph_con_close_socket(struct ceph_connection *con)
>          * shut the socket down.
>          */
>         ceph_con_flag_clear(con, CEPH_CON_F_SOCK_CLOSED);
> +       con->error_code = 0;
>
>         con_sock_state_closed(con);
>         return rc;
> @@ -1613,12 +1617,21 @@ static void ceph_con_workfn(struct work_struct *work)
>   */
>  static void con_fault(struct ceph_connection *con)
>  {
> +       int error_code;
> +
>         dout("fault %p state %d to peer %s\n",
>              con, con->state, ceph_pr_addr(&con->peer_addr));
>
> -       pr_warn("%s%lld %s %s\n", ENTITY_NAME(con->peer_name),
> -               ceph_pr_addr(&con->peer_addr), con->error_msg);
> +       error_code = READ_ONCE(con->error_code);
> +       if (error_code)
> +               pr_warn("%s%lld %s %s (%pe)\n", ENTITY_NAME(con->peer_name),
> +                       ceph_pr_addr(&con->peer_addr), con->error_msg,
> +                       ERR_PTR(error_code));
> +       else
> +               pr_warn("%s%lld %s %s\n", ENTITY_NAME(con->peer_name),
> +                       ceph_pr_addr(&con->peer_addr), con->error_msg);
>         con->error_msg = NULL;
> +       con->error_code = 0;
>
>         WARN_ON(con->state == CEPH_CON_S_STANDBY ||
>                 con->state == CEPH_CON_S_CLOSED);
> --
> 2.47.3
>