Re: [Qemu-devel] Re: [PATCH 2/4] migration-tcp: threaded tcp incoming migration.

[Yoshiaki Tamura]

2010/6/2 Anthony Liguori <address@hidden>:
> On 06/01/2010 11:23 AM, Yoshiaki Tamura wrote:
>>
>> 2010/6/2 Anthony Liguori<address@hidden>:
>>
>>>
>>> On 06/01/2010 10:40 AM, Yoshiaki Tamura wrote:
>>>
>>>>
>>>> Create a thread to handle tcp incoming migration when CONFIG_IOTHREAD
>>>> is enabled.  Spawned thread writes it's return status to th_fds[1]
>>>> before exit, and main thread joins and reads it.  In
>>>> tcp_start_incoming_migration(), allocate FdMigrationState and return
>>>> MigrationState to let migration to print incoming migration info.
>>>>
>>>>
>>>
>>> In the absence of any locking, I can't see how this is safe.
>>>
>>
>> Right.  If we use threading here, we need to prevent commands from
>> monitor that affects incoming thread.
>>
>
> There's a huge number of calls that can get made during live migration that
> can also be triggered by the monitor.
>
> Even the basic things likes qemu_set_fd_handler2 can cause havoc.
>
> Just preventing certain monitor commands is not sufficient.

Ah, that was my concern.  Sorry for not understanding well.
Thanks for your advice.

Yoshi

>
> Regards,
>
> Anthony Liguori
>
>> Thanks,
>>
>> Yoshi
>>
>>
>>>
>>> Regards,
>>>
>>> Anthony Liguori
>>>
>>>
>>>>
>>>> Signed-off-by: Yoshiaki Tamura<address@hidden>
>>>> ---
>>>>  migration-tcp.c |   86
>>>> ++++++++++++++++++++++++++++++++++++++++++++++---------
>>>>  migration.h     |    2 +-
>>>>  2 files changed, 73 insertions(+), 15 deletions(-)
>>>>
>>>> diff --git a/migration-tcp.c b/migration-tcp.c
>>>> index 95ce722..f20e5fe 100644
>>>> --- a/migration-tcp.c
>>>> +++ b/migration-tcp.c
>>>> @@ -18,6 +18,7 @@
>>>>  #include "sysemu.h"
>>>>  #include "buffered_file.h"
>>>>  #include "block.h"
>>>> +#include "qemu-thread.h"
>>>>
>>>>  //#define DEBUG_MIGRATION_TCP
>>>>
>>>> @@ -29,6 +30,11 @@
>>>>      do { } while (0)
>>>>  #endif
>>>>
>>>> +#ifdef CONFIG_IOTHREAD
>>>> +static QemuThread migration_thread;
>>>> +static int th_fds[2];
>>>> +#endif
>>>> +
>>>>  static int socket_errno(FdMigrationState *s)
>>>>  {
>>>>      return socket_error();
>>>> @@ -176,41 +182,93 @@ static void tcp_accept_incoming_migration(void
>>>> *opaque)
>>>>  out_fopen:
>>>>      qemu_fclose(f);
>>>>  out:
>>>> +#ifndef CONFIG_IOTHREAD
>>>>      qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);
>>>> +#endif
>>>>      close(s);
>>>>      close(c);
>>>> +#ifdef CONFIG_IOTHREAD
>>>> +    write(th_fds[1],&ret, sizeof(ret));
>>>> +    qemu_thread_exit(NULL);
>>>> +#endif
>>>> +}
>>>> +
>>>> +#ifdef CONFIG_IOTHREAD
>>>> +static void tcp_incoming_migration_complete(void *opaque)
>>>> +{
>>>> +    int ret, state = 0;
>>>> +    FdMigrationState *s = opaque;
>>>> +
>>>> +    qemu_thread_join(&migration_thread, NULL);
>>>> +
>>>> +    ret = read(th_fds[0],&state, sizeof(state));
>>>> +    if (ret == -1) {
>>>> +        fprintf(stderr, "failed to read from pipe\n");
>>>> +        goto err;
>>>> +    }
>>>> +
>>>> +    s->state = state<    0 ? MIG_STATE_ERROR : MIG_STATE_COMPLETED;
>>>> +
>>>> +err:
>>>> +    qemu_set_fd_handler2(th_fds[0], NULL, NULL, NULL, NULL);
>>>> +    close(th_fds[0]);
>>>> +    close(th_fds[1]);
>>>>  }
>>>> +#endif
>>>>
>>>> -int tcp_start_incoming_migration(const char *host_port)
>>>> +MigrationState *tcp_start_incoming_migration(const char *host_port)
>>>>  {
>>>>      struct sockaddr_in addr;
>>>> +    FdMigrationState *s;
>>>>      int val;
>>>> -    int s;
>>>>
>>>>      if (parse_host_port(&addr, host_port)<    0) {
>>>>          fprintf(stderr, "invalid host/port combination: %s\n",
>>>> host_port);
>>>> -        return -EINVAL;
>>>> +        return NULL;
>>>>      }
>>>>
>>>> -    s = qemu_socket(PF_INET, SOCK_STREAM, 0);
>>>> -    if (s == -1)
>>>> -        return -socket_error();
>>>> +    s = qemu_mallocz(sizeof(*s));
>>>> +
>>>> +    s->get_error = socket_errno;
>>>> +    s->close = tcp_close;
>>>> +    s->mig_state.cancel = migrate_fd_cancel;
>>>> +    s->mig_state.get_status = migrate_fd_get_status;
>>>> +    s->state = MIG_STATE_ACTIVE;
>>>> +
>>>> +    s->fd = qemu_socket(PF_INET, SOCK_STREAM, 0);
>>>> +    if (s->fd == -1) {
>>>> +        qemu_free(s);
>>>> +        return NULL;
>>>> +    }
>>>>
>>>>      val = 1;
>>>> -    setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (const char *)&val,
>>>> sizeof(val));
>>>> +    setsockopt(s->fd, SOL_SOCKET, SO_REUSEADDR,
>>>> +               (const char *)&val, sizeof(val));
>>>>
>>>> -    if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) == -1)
>>>> +    if (bind(s->fd, (struct sockaddr *)&addr, sizeof(addr)) == -1)
>>>>          goto err;
>>>>
>>>> -    if (listen(s, 1) == -1)
>>>> +    if (listen(s->fd, 1) == -1)
>>>>          goto err;
>>>>
>>>> -    qemu_set_fd_handler2(s, NULL, tcp_accept_incoming_migration, NULL,
>>>> -                         (void *)(unsigned long)s);
>>>> +#ifdef CONFIG_IOTHREAD
>>>> +    if (qemu_pipe(th_fds) == -1) {
>>>> +        fprintf(stderr, "failed to create pipe\n");
>>>> +        goto err;
>>>> +    }
>>>>
>>>> -    return 0;
>>>> +    qemu_thread_create(&migration_thread, (void
>>>> *)tcp_accept_incoming_migration,
>>>> +                       (void *)(unsigned long)s->fd);
>>>> +    qemu_set_fd_handler2(th_fds[0], NULL,
>>>> tcp_incoming_migration_complete, NULL,
>>>> +                         (void *)s);
>>>> +#else
>>>> +    qemu_set_fd_handler2(s->fd, NULL, tcp_accept_incoming_migration,
>>>> NULL,
>>>> +                         (void *)(unsigned long)s->fd);
>>>> +#endif
>>>> +
>>>> +    return&s->mig_state;
>>>>
>>>>  err:
>>>> -    close(s);
>>>> -    return -socket_error();
>>>> +    close(s->fd);
>>>> +    return NULL;
>>>>  }
>>>> diff --git a/migration.h b/migration.h
>>>> index 385423f..c11e6db 100644
>>>> --- a/migration.h
>>>> +++ b/migration.h
>>>> @@ -76,7 +76,7 @@ MigrationState *exec_start_outgoing_migration(Monitor
>>>> *mon,
>>>>                                              int blk,
>>>>                                              int inc);
>>>>
>>>> -int tcp_start_incoming_migration(const char *host_port);
>>>> +MigrationState *tcp_start_incoming_migration(const char *host_port);
>>>>
>>>>  MigrationState *tcp_start_outgoing_migration(Monitor *mon,
>>>>                                               const char *host_port,
>>>>
>>>>
>>>
>>>
>>>
>
>
>