packages/qemu
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

migration/multifd: fix hangup with TLS-Multifd due to blocking handshake

Browse Source 
The qemu main loop could hang up forever when we enable TLS+Multifd.
The Src multifd_send_0 invokes tls handshake, it sends hello to sever
and wait response.
However, the Dst main qemu loop has been waiting recvmsg() for multifd_recv_1.
Both of Src and Dst main qemu loop are blocking and waiting for reponse which
results in hanging up forever.

Src: (multifd_send_0)                                              Dst: (multifd_recv_1)
multifd_channel_connect                                            migration_channel_process_incoming
  multifd_tls_channel_connect                                        migration_tls_channel_process_incoming
    multifd_tls_channel_connect                                        qio_channel_tls_handshake_task
       qio_channel_tls_handshake                                         gnutls_handshake
          qio_channel_tls_handshake_task                                       ...
            qcrypto_tls_session_handshake                                      ...
              gnutls_handshake                                                 ...
                   ...                                                         ...
                recvmsg (Blocking I/O waiting for response)                recvmsg (Blocking I/O waiting for response)

Fix this by offloadinig handshake work to a background thread.

Reported-by: Yan Jin <jinyan12@huawei.com>
Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
Message-Id: <1604643893-8223-1-git-send-email-zhengchuan@huawei.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Huawei Technologies Co., Ltd 2020-12-02 14:50:12 +08:00 committed by Euler Robot
parent 990c68bae3
commit 9de3a5da88
1 changed files with 83 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

83
migration-multifd-fix-hangup-with-TLS-Multifd-due-to.patch Normal file
View File

@ -0,0 +1,83 @@
From 26ffadd08711aa4ef62932ac0ecf5048518b2801 Mon Sep 17 00:00:00 2001
From: Ying Fang <fangying1@huawei.com>
Date: Wed, 2 Dec 2020 14:50:12 +0800
Subject: [PATCH] migration/multifd: fix hangup with TLS-Multifd due to
blocking handshake
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
The qemu main loop could hang up forever when we enable TLS+Multifd.
The Src multifd_send_0 invokes tls handshake, it sends hello to sever
and wait response.
However, the Dst main qemu loop has been waiting recvmsg() for multifd_recv_1.
Both of Src and Dst main qemu loop are blocking and waiting for reponse which
results in hanging up forever.
Src: (multifd_send_0) Dst: (multifd_recv_1)
multifd_channel_connect migration_channel_process_incoming
multifd_tls_channel_connect migration_tls_channel_process_incoming
multifd_tls_channel_connect qio_channel_tls_handshake_task
qio_channel_tls_handshake gnutls_handshake
qio_channel_tls_handshake_task ...
qcrypto_tls_session_handshake ...
gnutls_handshake ...
... ...
recvmsg (Blocking I/O waiting for response) recvmsg (Blocking I/O waiting for response)
Fix this by offloadinig handshake work to a background thread.
Reported-by: Yan Jin <jinyan12@huawei.com>
Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
Message-Id: <1604643893-8223-1-git-send-email-zhengchuan@huawei.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
migration/ram.c | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)
diff --git a/migration/ram.c b/migration/ram.c
index dc9831d7f3..a37dbfc049 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1220,6 +1220,19 @@ static void multifd_tls_outgoing_handshake(QIOTask *task,
multifd_channel_connect(p, ioc, err);
}
+static void *multifd_tls_handshake_thread(void *opaque)
+{
+ MultiFDSendParams *p = opaque;
+ QIOChannelTLS *tioc = QIO_CHANNEL_TLS(p->c);
+
+ qio_channel_tls_handshake(tioc,
+ multifd_tls_outgoing_handshake,
+ p,
+ NULL,
+ NULL);
+ return NULL;
+}
+
static void multifd_tls_channel_connect(MultiFDSendParams *p,
QIOChannel *ioc,
Error **errp)
@@ -1235,12 +1248,10 @@ static void multifd_tls_channel_connect(MultiFDSendParams *p,
trace_multifd_tls_outgoing_handshake_start(ioc, tioc, hostname);
qio_channel_set_name(QIO_CHANNEL(tioc), "multifd-tls-outgoing");
- qio_channel_tls_handshake(tioc,
- multifd_tls_outgoing_handshake,
- p,
- NULL,
- NULL);
-
+ p->c = QIO_CHANNEL(tioc);
+ qemu_thread_create(&p->thread, "multifd-tls-handshake-worker",
+ multifd_tls_handshake_thread, p,
+ QEMU_THREAD_JOINABLE);
}
static bool multifd_channel_connect(MultiFDSendParams *p,
--
2.27.0