725c3b9978
- kvm-nbd-server-do-not-poll-within-a-coroutine-context.patch [RHEL-33440] - kvm-nbd-server-Mark-negotiation-functions-as-coroutine_f.patch [RHEL-33440] - Resolves: RHEL-33440 (Qemu hang when quit dst vm after storage migration(nbd+tls))
209 lines
6.9 KiB
Diff
209 lines
6.9 KiB
Diff
From ae9ebfc4ebd6f146951f04cf9e12eeaaf4c2387e Mon Sep 17 00:00:00 2001
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From: Zhu Yangyang <zhuyangyang14@huawei.com>
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Date: Mon, 8 Apr 2024 11:00:43 -0500
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Subject: [PATCH 1/2] nbd/server: do not poll within a coroutine context
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RH-Author: Eric Blake <eblake@redhat.com>
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RH-MergeRequest: 239: avoid destination hang on NBD+TLS storage migration
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RH-Jira: RHEL-33440
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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RH-Commit: [1/2] 27963e92aacca8ed43994113b645f472fba8f8bc (ebblake/centos-qemu-kvm)
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Coroutines are not supposed to block. Instead, they should yield.
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The client performs TLS upgrade outside of an AIOContext, during
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synchronous handshake; this still requires g_main_loop. But the
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server responds to TLS upgrade inside a coroutine, so a nested
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g_main_loop is wrong. Since the two callbacks no longer share more
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than the setting of data.complete and data.error, it's just as easy to
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use static helpers instead of trying to share a common code path. It
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is also possible to add assertions that no other code is interfering
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with the eventual path to qio reaching the callback, whether or not it
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required a yield or main loop.
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Fixes: f95910f ("nbd: implement TLS support in the protocol negotiation")
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Signed-off-by: Zhu Yangyang <zhuyangyang14@huawei.com>
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[eblake: move callbacks to their use point, add assertions]
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Signed-off-by: Eric Blake <eblake@redhat.com>
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Message-ID: <20240408160214.1200629-5-eblake@redhat.com>
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Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
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Jira: https://issues.redhat.com/browse/RHEL-33440
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(cherry picked from commit ae6d91a7e9b77abb029ed3fa9fad461422286942)
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Signed-off-by: Eric Blake <eblake@redhat.com>
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---
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nbd/client.c | 28 ++++++++++++++++++++++++----
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nbd/common.c | 11 -----------
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nbd/nbd-internal.h | 10 ----------
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nbd/server.c | 28 +++++++++++++++++++++++-----
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4 files changed, 47 insertions(+), 30 deletions(-)
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diff --git a/nbd/client.c b/nbd/client.c
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index 29ffc609a4..c89c750467 100644
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--- a/nbd/client.c
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+++ b/nbd/client.c
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@@ -596,13 +596,31 @@ static int nbd_request_simple_option(QIOChannel *ioc, int opt, bool strict,
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return 1;
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}
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+/* Callback to learn when QIO TLS upgrade is complete */
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+struct NBDTLSClientHandshakeData {
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+ bool complete;
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+ Error *error;
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+ GMainLoop *loop;
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+};
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+
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+static void nbd_client_tls_handshake(QIOTask *task, void *opaque)
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+{
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+ struct NBDTLSClientHandshakeData *data = opaque;
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+
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+ qio_task_propagate_error(task, &data->error);
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+ data->complete = true;
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+ if (data->loop) {
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+ g_main_loop_quit(data->loop);
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+ }
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+}
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+
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static QIOChannel *nbd_receive_starttls(QIOChannel *ioc,
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QCryptoTLSCreds *tlscreds,
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const char *hostname, Error **errp)
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{
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int ret;
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QIOChannelTLS *tioc;
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- struct NBDTLSHandshakeData data = { 0 };
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+ struct NBDTLSClientHandshakeData data = { 0 };
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ret = nbd_request_simple_option(ioc, NBD_OPT_STARTTLS, true, errp);
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if (ret <= 0) {
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@@ -619,18 +637,20 @@ static QIOChannel *nbd_receive_starttls(QIOChannel *ioc,
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return NULL;
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}
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qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-client-tls");
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- data.loop = g_main_loop_new(g_main_context_default(), FALSE);
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trace_nbd_receive_starttls_tls_handshake();
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qio_channel_tls_handshake(tioc,
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- nbd_tls_handshake,
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+ nbd_client_tls_handshake,
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&data,
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NULL,
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NULL);
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if (!data.complete) {
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+ data.loop = g_main_loop_new(g_main_context_default(), FALSE);
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g_main_loop_run(data.loop);
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+ assert(data.complete);
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+ g_main_loop_unref(data.loop);
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}
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- g_main_loop_unref(data.loop);
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+
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if (data.error) {
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error_propagate(errp, data.error);
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object_unref(OBJECT(tioc));
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diff --git a/nbd/common.c b/nbd/common.c
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index 3247c1d618..589a748cfe 100644
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--- a/nbd/common.c
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+++ b/nbd/common.c
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@@ -47,17 +47,6 @@ int nbd_drop(QIOChannel *ioc, size_t size, Error **errp)
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}
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-void nbd_tls_handshake(QIOTask *task,
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- void *opaque)
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-{
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- struct NBDTLSHandshakeData *data = opaque;
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-
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- qio_task_propagate_error(task, &data->error);
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- data->complete = true;
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- g_main_loop_quit(data->loop);
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-}
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-
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-
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const char *nbd_opt_lookup(uint32_t opt)
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{
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switch (opt) {
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diff --git a/nbd/nbd-internal.h b/nbd/nbd-internal.h
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index dfa02f77ee..91895106a9 100644
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--- a/nbd/nbd-internal.h
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+++ b/nbd/nbd-internal.h
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@@ -72,16 +72,6 @@ static inline int nbd_write(QIOChannel *ioc, const void *buffer, size_t size,
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return qio_channel_write_all(ioc, buffer, size, errp) < 0 ? -EIO : 0;
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}
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-struct NBDTLSHandshakeData {
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- GMainLoop *loop;
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- bool complete;
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- Error *error;
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-};
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-
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-
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-void nbd_tls_handshake(QIOTask *task,
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- void *opaque);
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-
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int nbd_drop(QIOChannel *ioc, size_t size, Error **errp);
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#endif
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diff --git a/nbd/server.c b/nbd/server.c
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index c3484cc1eb..98ae0e1632 100644
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--- a/nbd/server.c
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+++ b/nbd/server.c
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@@ -748,6 +748,23 @@ static int nbd_negotiate_handle_info(NBDClient *client, Error **errp)
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return rc;
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}
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+/* Callback to learn when QIO TLS upgrade is complete */
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+struct NBDTLSServerHandshakeData {
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+ bool complete;
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+ Error *error;
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+ Coroutine *co;
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+};
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+
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+static void nbd_server_tls_handshake(QIOTask *task, void *opaque)
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+{
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+ struct NBDTLSServerHandshakeData *data = opaque;
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+
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+ qio_task_propagate_error(task, &data->error);
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+ data->complete = true;
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+ if (!qemu_coroutine_entered(data->co)) {
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+ aio_co_wake(data->co);
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+ }
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+}
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/* Handle NBD_OPT_STARTTLS. Return NULL to drop connection, or else the
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* new channel for all further (now-encrypted) communication. */
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@@ -756,7 +773,7 @@ static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,
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{
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QIOChannel *ioc;
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QIOChannelTLS *tioc;
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- struct NBDTLSHandshakeData data = { 0 };
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+ struct NBDTLSServerHandshakeData data = { 0 };
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assert(client->opt == NBD_OPT_STARTTLS);
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@@ -777,17 +794,18 @@ static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,
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qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-server-tls");
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trace_nbd_negotiate_handle_starttls_handshake();
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- data.loop = g_main_loop_new(g_main_context_default(), FALSE);
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+ data.co = qemu_coroutine_self();
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qio_channel_tls_handshake(tioc,
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- nbd_tls_handshake,
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+ nbd_server_tls_handshake,
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&data,
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NULL,
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NULL);
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if (!data.complete) {
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- g_main_loop_run(data.loop);
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+ qemu_coroutine_yield();
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+ assert(data.complete);
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}
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- g_main_loop_unref(data.loop);
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+
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if (data.error) {
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object_unref(OBJECT(tioc));
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error_propagate(errp, data.error);
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--
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2.39.3
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