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[PATCH] migration/multifd: fix hangup with TLS-Multifd due to blocking h
From: |
Chuan Zheng |
Subject: |
[PATCH] migration/multifd: fix hangup with TLS-Multifd due to blocking handshake |
Date: |
Fri, 6 Nov 2020 14:24:53 +0800 |
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>
---
migration/multifd.c | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)
diff --git a/migration/multifd.c b/migration/multifd.c
index 68b171f..88486b9 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -739,6 +739,19 @@ 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)
@@ -754,12 +767,10 @@ 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,
--
1.8.3.1
- [PATCH] migration/multifd: fix hangup with TLS-Multifd due to blocking handshake,
Chuan Zheng <=