migration.c - qemu - Git at Google

 /*
  * QEMU live migration
  *
  * Copyright IBM, Corp. 2008
  *
  * Authors:
  *  Anthony Liguori   <aliguori@us.ibm.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2.  See
  * the COPYING file in the top-level directory.
  *
  */

 #include "qemu-common.h"
 #include "migration.h"
 #include "monitor.h"
 #include "buffered_file.h"
 #include "sysemu.h"
 #include "block.h"
 #include "qemu_socket.h"
 #include "block-migration.h"
 #include "qemu-objects.h"

 //#define DEBUG_MIGRATION

 #ifdef DEBUG_MIGRATION
 #define DPRINTF(fmt, ...) \
     do { printf("migration: " fmt, ## __VA_ARGS__); } while (0)
 #else
 #define DPRINTF(fmt, ...) \
     do { } while (0)
 #endif

 /* Migration speed throttling */
 static int64_t max_throttle = (32 << 20);

 static MigrationState *current_migration;

 int qemu_start_incoming_migration(const char *uri)
 {
     const char *p;
     int ret;

     if (strstart(uri, "tcp:", &p))
         ret = tcp_start_incoming_migration(p);
 #if !defined(WIN32)
     else if (strstart(uri, "exec:", &p))
         ret =  exec_start_incoming_migration(p);
     else if (strstart(uri, "unix:", &p))
         ret = unix_start_incoming_migration(p);
     else if (strstart(uri, "fd:", &p))
         ret = fd_start_incoming_migration(p);
 #endif
     else {
         fprintf(stderr, "unknown migration protocol: %s\n", uri);
         ret = -EPROTONOSUPPORT;
     }
     return ret;
 }

 void process_incoming_migration(QEMUFile *f)
 {
     if (qemu_loadvm_state(f) < 0) {
         fprintf(stderr, "load of migration failed\n");
         exit(0);
     }
     qemu_announce_self();
     DPRINTF("successfully loaded vm state\n");

     incoming_expected = false;

     if (autostart)
         vm_start();
 }

 int do_migrate(Monitor *mon, const QDict *qdict, QObject **ret_data)
 {
     MigrationState *s = NULL;
     const char *p;
     int detach = qdict_get_try_bool(qdict, "detach", 0);
     int blk = qdict_get_try_bool(qdict, "blk", 0);
     int inc = qdict_get_try_bool(qdict, "inc", 0);
     const char *uri = qdict_get_str(qdict, "uri");

     if (current_migration &&
         current_migration->get_status(current_migration) == MIG_STATE_ACTIVE) {
         monitor_printf(mon, "migration already in progress\n");
         return -1;
     }

     if (strstart(uri, "tcp:", &p)) {
         s = tcp_start_outgoing_migration(mon, p, max_throttle, detach,
                                          blk, inc);
 #if !defined(WIN32)
     } else if (strstart(uri, "exec:", &p)) {
         s = exec_start_outgoing_migration(mon, p, max_throttle, detach,
                                           blk, inc);
     } else if (strstart(uri, "unix:", &p)) {
         s = unix_start_outgoing_migration(mon, p, max_throttle, detach,
                                           blk, inc);
     } else if (strstart(uri, "fd:", &p)) {
         s = fd_start_outgoing_migration(mon, p, max_throttle, detach,
                                         blk, inc);
 #endif
     } else {
         monitor_printf(mon, "unknown migration protocol: %s\n", uri);
         return -1;
     }

     if (s == NULL) {
         monitor_printf(mon, "migration failed\n");
         return -1;
     }

     if (current_migration) {
         current_migration->release(current_migration);
     }

     current_migration = s;
     return 0;
 }

 int do_migrate_cancel(Monitor *mon, const QDict *qdict, QObject **ret_data)
 {
     MigrationState *s = current_migration;

     if (s)
         s->cancel(s);

     return 0;
 }

 int do_migrate_set_speed(Monitor *mon, const QDict *qdict, QObject **ret_data)
 {
     int64_t d;
     FdMigrationState *s;

     d = qdict_get_int(qdict, "value");
     if (d < 0) {
         d = 0;
     }
     max_throttle = d;

     s = migrate_to_fms(current_migration);
     if (s && s->file) {
         qemu_file_set_rate_limit(s->file, max_throttle);
     }

     return 0;
 }

 /* amount of nanoseconds we are willing to wait for migration to be down.
  * the choice of nanoseconds is because it is the maximum resolution that
  * get_clock() can achieve. It is an internal measure. All user-visible
  * units must be in seconds */
 static uint64_t max_downtime = 30000000;

 uint64_t migrate_max_downtime(void)
 {
     return max_downtime;
 }

 int do_migrate_set_downtime(Monitor *mon, const QDict *qdict,
                             QObject **ret_data)
 {
     double d;

     d = qdict_get_double(qdict, "value") * 1e9;
     d = MAX(0, MIN(UINT64_MAX, d));
     max_downtime = (uint64_t)d;

     return 0;
 }

 static void migrate_print_status(Monitor *mon, const char *name,
                                  const QDict *status_dict)
 {
     QDict *qdict;

     qdict = qobject_to_qdict(qdict_get(status_dict, name));

     monitor_printf(mon, "transferred %s: %" PRIu64 " kbytes\n", name,
                         qdict_get_int(qdict, "transferred") >> 10);
     monitor_printf(mon, "remaining %s: %" PRIu64 " kbytes\n", name,
                         qdict_get_int(qdict, "remaining") >> 10);
     monitor_printf(mon, "total %s: %" PRIu64 " kbytes\n", name,
                         qdict_get_int(qdict, "total") >> 10);
 }

 void do_info_migrate_print(Monitor *mon, const QObject *data)
 {
     QDict *qdict;

     qdict = qobject_to_qdict(data);

     monitor_printf(mon, "Migration status: %s\n",
                    qdict_get_str(qdict, "status"));

     if (qdict_haskey(qdict, "ram")) {
         migrate_print_status(mon, "ram", qdict);
     }

     if (qdict_haskey(qdict, "disk")) {
         migrate_print_status(mon, "disk", qdict);
     }
 }

 static void migrate_put_status(QDict *qdict, const char *name,
                                uint64_t trans, uint64_t rem, uint64_t total)
 {
     QObject *obj;

     obj = qobject_from_jsonf("{ 'transferred': %" PRId64 ", "
                                "'remaining': %" PRId64 ", "
                                "'total': %" PRId64 " }", trans, rem, total);
     qdict_put_obj(qdict, name, obj);
 }

 void do_info_migrate(Monitor *mon, QObject **ret_data)
 {
     QDict *qdict;
     MigrationState *s = current_migration;

     if (s) {
         switch (s->get_status(s)) {
         case MIG_STATE_ACTIVE:
             qdict = qdict_new();
             qdict_put(qdict, "status", qstring_from_str("active"));

             migrate_put_status(qdict, "ram", ram_bytes_transferred(),
                                ram_bytes_remaining(), ram_bytes_total());

             if (blk_mig_active()) {
                 migrate_put_status(qdict, "disk", blk_mig_bytes_transferred(),
                                    blk_mig_bytes_remaining(),
                                    blk_mig_bytes_total());
             }

             *ret_data = QOBJECT(qdict);
             break;
         case MIG_STATE_COMPLETED:
             *ret_data = qobject_from_jsonf("{ 'status': 'completed' }");
             break;
         case MIG_STATE_ERROR:
             *ret_data = qobject_from_jsonf("{ 'status': 'failed' }");
             break;
         case MIG_STATE_CANCELLED:
             *ret_data = qobject_from_jsonf("{ 'status': 'cancelled' }");
             break;
         }
     }
 }

 /* shared migration helpers */

 void migrate_fd_monitor_suspend(FdMigrationState *s, Monitor *mon)
 {
     s->mon = mon;
     if (monitor_suspend(mon) == 0) {
         DPRINTF("suspending monitor\n");
     } else {
         monitor_printf(mon, "terminal does not allow synchronous "
                        "migration, continuing detached\n");
     }
 }

 void migrate_fd_error(FdMigrationState *s)
 {
     DPRINTF("setting error state\n");
     s->state = MIG_STATE_ERROR;
     migrate_fd_cleanup(s);
 }

 int migrate_fd_cleanup(FdMigrationState *s)
 {
     int ret = 0;

     qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);

     if (s->file) {
         DPRINTF("closing file\n");
         if (qemu_fclose(s->file) != 0) {
             ret = -1;
         }
         s->file = NULL;
     }

     if (s->fd != -1)
         close(s->fd);

     /* Don't resume monitor until we've flushed all of the buffers */
     if (s->mon) {
         monitor_resume(s->mon);
     }

     s->fd = -1;

     return ret;
 }

 void migrate_fd_put_notify(void *opaque)
 {
     FdMigrationState *s = opaque;

     qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
     qemu_file_put_notify(s->file);
 }

 ssize_t migrate_fd_put_buffer(void *opaque, const void *data, size_t size)
 {
     FdMigrationState *s = opaque;
     ssize_t ret;

     do {
         ret = s->write(s, data, size);
     } while (ret == -1 && ((s->get_error(s)) == EINTR));

     if (ret == -1)
         ret = -(s->get_error(s));

     if (ret == -EAGAIN) {
         qemu_set_fd_handler2(s->fd, NULL, NULL, migrate_fd_put_notify, s);
     } else if (ret < 0) {
         if (s->mon) {
             monitor_resume(s->mon);
         }
         s->state = MIG_STATE_ERROR;
     }

     return ret;
 }

 void migrate_fd_connect(FdMigrationState *s)
 {
     int ret;

     s->file = qemu_fopen_ops_buffered(s,
                                       s->bandwidth_limit,
                                       migrate_fd_put_buffer,
                                       migrate_fd_put_ready,
                                       migrate_fd_wait_for_unfreeze,
                                       migrate_fd_close);

     DPRINTF("beginning savevm\n");
     ret = qemu_savevm_state_begin(s->mon, s->file, s->mig_state.blk,
                                   s->mig_state.shared);
     if (ret < 0) {
         DPRINTF("failed, %d\n", ret);
         migrate_fd_error(s);
         return;
     }

     migrate_fd_put_ready(s);
 }

 void migrate_fd_put_ready(void *opaque)
 {
     FdMigrationState *s = opaque;

     if (s->state != MIG_STATE_ACTIVE) {
         DPRINTF("put_ready returning because of non-active state\n");
         return;
     }

     DPRINTF("iterate\n");
     if (qemu_savevm_state_iterate(s->mon, s->file) == 1) {
         int state;
         int old_vm_running = vm_running;

         DPRINTF("done iterating\n");
         vm_stop(0);

         if ((qemu_savevm_state_complete(s->mon, s->file)) < 0) {
             if (old_vm_running) {
                 vm_start();
             }
             state = MIG_STATE_ERROR;
         } else {
             state = MIG_STATE_COMPLETED;
         }
         if (migrate_fd_cleanup(s) < 0) {
             if (old_vm_running) {
                 vm_start();
             }
             state = MIG_STATE_ERROR;
         }
         s->state = state;
     }
 }

 int migrate_fd_get_status(MigrationState *mig_state)
 {
     FdMigrationState *s = migrate_to_fms(mig_state);
     return s->state;
 }

 void migrate_fd_cancel(MigrationState *mig_state)
 {
     FdMigrationState *s = migrate_to_fms(mig_state);

     if (s->state != MIG_STATE_ACTIVE)
         return;

     DPRINTF("cancelling migration\n");

     s->state = MIG_STATE_CANCELLED;
     qemu_savevm_state_cancel(s->mon, s->file);

     migrate_fd_cleanup(s);
 }

 void migrate_fd_release(MigrationState *mig_state)
 {
     FdMigrationState *s = migrate_to_fms(mig_state);

     DPRINTF("releasing state\n");

     if (s->state == MIG_STATE_ACTIVE) {
         s->state = MIG_STATE_CANCELLED;
         migrate_fd_cleanup(s);
     }
     qemu_free(s);
 }

 void migrate_fd_wait_for_unfreeze(void *opaque)
 {
     FdMigrationState *s = opaque;
     int ret;

     DPRINTF("wait for unfreeze\n");
     if (s->state != MIG_STATE_ACTIVE)
         return;

     do {
         fd_set wfds;

         FD_ZERO(&wfds);
         FD_SET(s->fd, &wfds);

         ret = select(s->fd + 1, NULL, &wfds, NULL, NULL);
     } while (ret == -1 && (s->get_error(s)) == EINTR);
 }

 int migrate_fd_close(void *opaque)
 {
     FdMigrationState *s = opaque;

     qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
     return s->close(s);
 }
	/*
	* QEMU live migration
	*
	* Copyright IBM, Corp. 2008
	*
	* Authors:
	* Anthony Liguori <aliguori@us.ibm.com>
	*
	* This work is licensed under the terms of the GNU GPL, version 2. See
	* the COPYING file in the top-level directory.
	*
	*/

	#include "qemu-common.h"
	#include "migration.h"
	#include "monitor.h"
	#include "buffered_file.h"
	#include "sysemu.h"
	#include "block.h"
	#include "qemu_socket.h"
	#include "block-migration.h"
	#include "qemu-objects.h"

	//#define DEBUG_MIGRATION

	#ifdef DEBUG_MIGRATION
	#define DPRINTF(fmt, ...) \
	do { printf("migration: " fmt, ## __VA_ARGS__); } while (0)
	#else
	#define DPRINTF(fmt, ...) \
	do { } while (0)
	#endif

	/* Migration speed throttling */
	static int64_t max_throttle = (32 << 20);

	static MigrationState *current_migration;

	int qemu_start_incoming_migration(const char *uri)
	{
	const char *p;
	int ret;

	if (strstart(uri, "tcp:", &p))
	ret = tcp_start_incoming_migration(p);
	#if !defined(WIN32)
	else if (strstart(uri, "exec:", &p))
	ret = exec_start_incoming_migration(p);
	else if (strstart(uri, "unix:", &p))
	ret = unix_start_incoming_migration(p);
	else if (strstart(uri, "fd:", &p))
	ret = fd_start_incoming_migration(p);
	#endif
	else {
	fprintf(stderr, "unknown migration protocol: %s\n", uri);
	ret = -EPROTONOSUPPORT;
	}
	return ret;
	}

	void process_incoming_migration(QEMUFile *f)
	{
	if (qemu_loadvm_state(f) < 0) {
	fprintf(stderr, "load of migration failed\n");
	exit(0);
	}
	qemu_announce_self();
	DPRINTF("successfully loaded vm state\n");

	incoming_expected = false;

	if (autostart)
	vm_start();
	}

	int do_migrate(Monitor mon, const QDict qdict, QObject **ret_data)
	{
	MigrationState *s = NULL;
	const char *p;
	int detach = qdict_get_try_bool(qdict, "detach", 0);
	int blk = qdict_get_try_bool(qdict, "blk", 0);
	int inc = qdict_get_try_bool(qdict, "inc", 0);
	const char *uri = qdict_get_str(qdict, "uri");

	if (current_migration &&
	current_migration->get_status(current_migration) == MIG_STATE_ACTIVE) {
	monitor_printf(mon, "migration already in progress\n");
	return -1;
	}

	if (strstart(uri, "tcp:", &p)) {
	s = tcp_start_outgoing_migration(mon, p, max_throttle, detach,
	blk, inc);
	#if !defined(WIN32)
	} else if (strstart(uri, "exec:", &p)) {
	s = exec_start_outgoing_migration(mon, p, max_throttle, detach,
	blk, inc);
	} else if (strstart(uri, "unix:", &p)) {
	s = unix_start_outgoing_migration(mon, p, max_throttle, detach,
	blk, inc);
	} else if (strstart(uri, "fd:", &p)) {
	s = fd_start_outgoing_migration(mon, p, max_throttle, detach,
	blk, inc);
	#endif
	} else {
	monitor_printf(mon, "unknown migration protocol: %s\n", uri);
	return -1;
	}

	if (s == NULL) {
	monitor_printf(mon, "migration failed\n");
	return -1;
	}

	if (current_migration) {
	current_migration->release(current_migration);
	}

	current_migration = s;
	return 0;
	}

	int do_migrate_cancel(Monitor mon, const QDict qdict, QObject **ret_data)
	{
	MigrationState *s = current_migration;

	if (s)
	s->cancel(s);

	return 0;
	}

	int do_migrate_set_speed(Monitor mon, const QDict qdict, QObject **ret_data)
	{
	int64_t d;
	FdMigrationState *s;

	d = qdict_get_int(qdict, "value");
	if (d < 0) {
	d = 0;
	}
	max_throttle = d;

	s = migrate_to_fms(current_migration);
	if (s && s->file) {
	qemu_file_set_rate_limit(s->file, max_throttle);
	}

	return 0;
	}

	/* amount of nanoseconds we are willing to wait for migration to be down.
	* the choice of nanoseconds is because it is the maximum resolution that
	* get_clock() can achieve. It is an internal measure. All user-visible
	* units must be in seconds */
	static uint64_t max_downtime = 30000000;

	uint64_t migrate_max_downtime(void)
	{
	return max_downtime;
	}

	int do_migrate_set_downtime(Monitor mon, const QDict qdict,
	QObject **ret_data)
	{
	double d;

	d = qdict_get_double(qdict, "value") * 1e9;
	d = MAX(0, MIN(UINT64_MAX, d));
	max_downtime = (uint64_t)d;

	return 0;
	}

	static void migrate_print_status(Monitor mon, const char name,
	const QDict *status_dict)
	{
	QDict *qdict;

	qdict = qobject_to_qdict(qdict_get(status_dict, name));

	monitor_printf(mon, "transferred %s: %" PRIu64 " kbytes\n", name,
	qdict_get_int(qdict, "transferred") >> 10);
	monitor_printf(mon, "remaining %s: %" PRIu64 " kbytes\n", name,
	qdict_get_int(qdict, "remaining") >> 10);
	monitor_printf(mon, "total %s: %" PRIu64 " kbytes\n", name,
	qdict_get_int(qdict, "total") >> 10);
	}

	void do_info_migrate_print(Monitor mon, const QObject data)
	{
	QDict *qdict;

	qdict = qobject_to_qdict(data);

	monitor_printf(mon, "Migration status: %s\n",
	qdict_get_str(qdict, "status"));

	if (qdict_haskey(qdict, "ram")) {
	migrate_print_status(mon, "ram", qdict);
	}

	if (qdict_haskey(qdict, "disk")) {
	migrate_print_status(mon, "disk", qdict);
	}
	}

	static void migrate_put_status(QDict qdict, const char name,
	uint64_t trans, uint64_t rem, uint64_t total)
	{
	QObject *obj;

	obj = qobject_from_jsonf("{ 'transferred': %" PRId64 ", "
	"'remaining': %" PRId64 ", "
	"'total': %" PRId64 " }", trans, rem, total);
	qdict_put_obj(qdict, name, obj);
	}

	void do_info_migrate(Monitor mon, QObject *ret_data)
	{
	QDict *qdict;
	MigrationState *s = current_migration;

	if (s) {
	switch (s->get_status(s)) {
	case MIG_STATE_ACTIVE:
	qdict = qdict_new();
	qdict_put(qdict, "status", qstring_from_str("active"));

	migrate_put_status(qdict, "ram", ram_bytes_transferred(),
	ram_bytes_remaining(), ram_bytes_total());

	if (blk_mig_active()) {
	migrate_put_status(qdict, "disk", blk_mig_bytes_transferred(),
	blk_mig_bytes_remaining(),
	blk_mig_bytes_total());
	}

	*ret_data = QOBJECT(qdict);
	break;
	case MIG_STATE_COMPLETED:
	*ret_data = qobject_from_jsonf("{ 'status': 'completed' }");
	break;
	case MIG_STATE_ERROR:
	*ret_data = qobject_from_jsonf("{ 'status': 'failed' }");
	break;
	case MIG_STATE_CANCELLED:
	*ret_data = qobject_from_jsonf("{ 'status': 'cancelled' }");
	break;
	}
	}
	}

	/* shared migration helpers */

	void migrate_fd_monitor_suspend(FdMigrationState s, Monitor mon)
	{
	s->mon = mon;
	if (monitor_suspend(mon) == 0) {
	DPRINTF("suspending monitor\n");
	} else {
	monitor_printf(mon, "terminal does not allow synchronous "
	"migration, continuing detached\n");
	}
	}

	void migrate_fd_error(FdMigrationState *s)
	{
	DPRINTF("setting error state\n");
	s->state = MIG_STATE_ERROR;
	migrate_fd_cleanup(s);
	}

	int migrate_fd_cleanup(FdMigrationState *s)
	{
	int ret = 0;

	qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);

	if (s->file) {
	DPRINTF("closing file\n");
	if (qemu_fclose(s->file) != 0) {
	ret = -1;
	}
	s->file = NULL;
	}

	if (s->fd != -1)
	close(s->fd);

	/* Don't resume monitor until we've flushed all of the buffers */
	if (s->mon) {
	monitor_resume(s->mon);
	}

	s->fd = -1;

	return ret;
	}

	void migrate_fd_put_notify(void *opaque)
	{
	FdMigrationState *s = opaque;

	qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
	qemu_file_put_notify(s->file);
	}

	ssize_t migrate_fd_put_buffer(void opaque, const void data, size_t size)
	{
	FdMigrationState *s = opaque;
	ssize_t ret;

	do {
	ret = s->write(s, data, size);
	} while (ret == -1 && ((s->get_error(s)) == EINTR));

	if (ret == -1)
	ret = -(s->get_error(s));

	if (ret == -EAGAIN) {
	qemu_set_fd_handler2(s->fd, NULL, NULL, migrate_fd_put_notify, s);
	} else if (ret < 0) {
	if (s->mon) {
	monitor_resume(s->mon);
	}
	s->state = MIG_STATE_ERROR;
	}

	return ret;
	}

	void migrate_fd_connect(FdMigrationState *s)
	{
	int ret;

	s->file = qemu_fopen_ops_buffered(s,
	s->bandwidth_limit,
	migrate_fd_put_buffer,
	migrate_fd_put_ready,
	migrate_fd_wait_for_unfreeze,
	migrate_fd_close);

	DPRINTF("beginning savevm\n");
	ret = qemu_savevm_state_begin(s->mon, s->file, s->mig_state.blk,
	s->mig_state.shared);
	if (ret < 0) {
	DPRINTF("failed, %d\n", ret);
	migrate_fd_error(s);
	return;
	}

	migrate_fd_put_ready(s);
	}

	void migrate_fd_put_ready(void *opaque)
	{
	FdMigrationState *s = opaque;

	if (s->state != MIG_STATE_ACTIVE) {
	DPRINTF("put_ready returning because of non-active state\n");
	return;
	}

	DPRINTF("iterate\n");
	if (qemu_savevm_state_iterate(s->mon, s->file) == 1) {
	int state;
	int old_vm_running = vm_running;

	DPRINTF("done iterating\n");
	vm_stop(0);

	if ((qemu_savevm_state_complete(s->mon, s->file)) < 0) {
	if (old_vm_running) {
	vm_start();
	}
	state = MIG_STATE_ERROR;
	} else {
	state = MIG_STATE_COMPLETED;
	}
	if (migrate_fd_cleanup(s) < 0) {
	if (old_vm_running) {
	vm_start();
	}
	state = MIG_STATE_ERROR;
	}
	s->state = state;
	}
	}

	int migrate_fd_get_status(MigrationState *mig_state)
	{
	FdMigrationState *s = migrate_to_fms(mig_state);
	return s->state;
	}

	void migrate_fd_cancel(MigrationState *mig_state)
	{
	FdMigrationState *s = migrate_to_fms(mig_state);

	if (s->state != MIG_STATE_ACTIVE)
	return;

	DPRINTF("cancelling migration\n");

	s->state = MIG_STATE_CANCELLED;
	qemu_savevm_state_cancel(s->mon, s->file);

	migrate_fd_cleanup(s);
	}

	void migrate_fd_release(MigrationState *mig_state)
	{
	FdMigrationState *s = migrate_to_fms(mig_state);

	DPRINTF("releasing state\n");

	if (s->state == MIG_STATE_ACTIVE) {
	s->state = MIG_STATE_CANCELLED;
	migrate_fd_cleanup(s);
	}
	qemu_free(s);
	}

	void migrate_fd_wait_for_unfreeze(void *opaque)
	{
	FdMigrationState *s = opaque;
	int ret;

	DPRINTF("wait for unfreeze\n");
	if (s->state != MIG_STATE_ACTIVE)
	return;

	do {
	fd_set wfds;

	FD_ZERO(&wfds);
	FD_SET(s->fd, &wfds);

	ret = select(s->fd + 1, NULL, &wfds, NULL, NULL);
	} while (ret == -1 && (s->get_error(s)) == EINTR);
	}

	int migrate_fd_close(void *opaque)
	{
	FdMigrationState *s = opaque;

	qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
	return s->close(s);
	}