Re: [PATCH 4/9] libceph: fix mutex coverage for ceph_con_close

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Reviewed-by: Yehuda Sadeh <yehuda@xxxxxxxxxxx>

On Fri, Jul 20, 2012 at 5:41 PM, Sage Weil <sage@xxxxxxxxxxx> wrote:
> Hold the mutex while twiddling all of the state bits to avoid possible
> races.  While we're here, make not of why we cannot close the socket
> directly.
>
> Signed-off-by: Sage Weil <sage@xxxxxxxxxxx>
> ---
>  net/ceph/messenger.c |    8 +++++++-
>  1 files changed, 7 insertions(+), 1 deletions(-)
>
> diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
> index 7105908..e24310e 100644
> --- a/net/ceph/messenger.c
> +++ b/net/ceph/messenger.c
> @@ -503,6 +503,7 @@ static void reset_connection(struct ceph_connection *con)
>   */
>  void ceph_con_close(struct ceph_connection *con)
>  {
> +       mutex_lock(&con->mutex);
>         dout("con_close %p peer %s\n", con,
>              ceph_pr_addr(&con->peer_addr.in_addr));
>         clear_bit(NEGOTIATING, &con->state);
> @@ -515,11 +516,16 @@ void ceph_con_close(struct ceph_connection *con)
>         clear_bit(KEEPALIVE_PENDING, &con->flags);
>         clear_bit(WRITE_PENDING, &con->flags);
>
> -       mutex_lock(&con->mutex);
>         reset_connection(con);
>         con->peer_global_seq = 0;
>         cancel_delayed_work(&con->work);
>         mutex_unlock(&con->mutex);
> +
> +       /*
> +        * We cannot close the socket directly from here because the
> +        * work threads use it without holding the mutex.  Instead, let
> +        * con_work() do it.
> +        */
>         queue_con(con);
>  }
>  EXPORT_SYMBOL(ceph_con_close);
> --
> 1.7.9
>
> --
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