Re: [Qemu-devel] [PATCH v4 4/4] Clear handler only for valid fd

[Markus Armbruster]

Orit Wasserman <address@hidden> writes:

> Signed-off-by: Orit Wasserman <address@hidden>
> ---
>  migration.c |    3 +--
>  1 files changed, 1 insertions(+), 2 deletions(-)
>
> diff --git a/migration.c b/migration.c
> index 1edeec5..c20a2fe 100644
> --- a/migration.c
> +++ b/migration.c
> @@ -240,8 +240,6 @@ static int migrate_fd_cleanup(MigrationState *s)
>  {
>      int ret = 0;
>  
> -    qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
> -
>      if (s->file) {
>          DPRINTF("closing file\n");
>          ret = qemu_fclose(s->file);
> @@ -249,6 +247,7 @@ static int migrate_fd_cleanup(MigrationState *s)
>      }
>  
>      if (s->fd != -1) {
> +        qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
>          close(s->fd);
>          s->fd = -1;
>      }

As far as I can see, qemu_set_fd_handler2() treats invalid file
descriptor -1 just like any other.  If it's in io_handlers, it gets
deleted, else it's a nop.  Thus, the old code works.  But I agree
passing invalid file descriptors is abusing the interface.

I'm not sufficiently familiar with the migration code to judge whether
moving the handler reset down is safe.