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SubjectRe: [PATCH 1/2] cifs: smbd: avoid reconnect lockup
Looks good to me (both patches)

Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>

On Sat, Mar 31, 2018 at 8:16 AM, Long Li <longli@linuxonhyperv.com> wrote:
> From: Long Li <longli@microsoft.com>
>
> During transport reconnect, other processes may have registered memory
> and blocked on transport. This creates a deadlock situation because the
> transport resources can't be freed, and reconnect is blocked.
>
> Fix this by returning to upper layer on timeout. Before returning,
> transport status is set to reconnecting so other processes will release
> memory registration resources.
>
> Upper layer will retry the reconnect. This is not in fast I/O path so
> setting the timeout to 5 seconds.
>
> Signed-off-by: Long Li <longli@microsoft.com>
> ---
> fs/cifs/smbdirect.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c
> index 5aa0b54..3f7883e 100644
> --- a/fs/cifs/smbdirect.c
> +++ b/fs/cifs/smbdirect.c
> @@ -1498,8 +1498,8 @@ int smbd_reconnect(struct TCP_Server_Info *server)
> log_rdma_event(INFO, "reconnecting rdma session\n");
>
> if (!server->smbd_conn) {
> - log_rdma_event(ERR, "rdma session already destroyed\n");
> - return -EINVAL;
> + log_rdma_event(INFO, "rdma session already destroyed\n");
> + goto create_conn;
> }
>
> /*
> @@ -1512,15 +1512,19 @@ int smbd_reconnect(struct TCP_Server_Info *server)
> }
>
> /* wait until the transport is destroyed */
> - wait_event(server->smbd_conn->wait_destroy,
> - server->smbd_conn->transport_status == SMBD_DESTROYED);
> + if (!wait_event_timeout(server->smbd_conn->wait_destroy,
> + server->smbd_conn->transport_status == SMBD_DESTROYED, 5*HZ))
> + return -EAGAIN;
>
> destroy_workqueue(server->smbd_conn->workqueue);
> kfree(server->smbd_conn);
>
> +create_conn:
> log_rdma_event(INFO, "creating rdma session\n");
> server->smbd_conn = smbd_get_connection(
> server, (struct sockaddr *) &server->dstaddr);
> + log_rdma_event(INFO, "created rdma session info=%p\n",
> + server->smbd_conn);
>
> return server->smbd_conn ? 0 : -ENOENT;
> }
> --
> 2.7.4
>
> --
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