Re: [Qemu-devel] [PATCH 1/4] char: add a post_load callback

[Anthony Liguori <aliguori@us.ibm.com>]

Alon Levy <alevy@redhat.com> writes:

>> Alon Levy <alevy@redhat.com> writes:
>> 
>> > Signed-off-by: Alon Levy <alevy@redhat.com>
>> > ---
>> >  include/char/char.h | 12 ++++++++++++
>> >  qemu-char.c         |  7 +++++++
>> >  2 files changed, 19 insertions(+)
>> >
>> > diff --git a/include/char/char.h b/include/char/char.h
>> > index 0326b2a..0fdcaf9 100644
>> > --- a/include/char/char.h
>> > +++ b/include/char/char.h
>> > @@ -70,6 +70,7 @@ struct CharDriverState {
>> >      void (*chr_set_echo)(struct CharDriverState *chr, bool echo);
>> >      void (*chr_guest_open)(struct CharDriverState *chr);
>> >      void (*chr_guest_close)(struct CharDriverState *chr);
>> > +    void (*chr_post_load)(struct CharDriverState *chr, int
>> > connected);
>> 
>> The character device layer should *not* be messing around with
>> notifying
>> migration state.
>> 
>> I thought we previously discussed this?  Just implement a migration
>> hook
>> in the spice code.
>
> The thing Gerd objected to when I sent a patch doing just that was the
> way I used the vmstate, one possible way to not have to use vmstate at
> all is adding api for querying the current front end connected status,
> like qemu_fe_is_connected. Is that acceptable?

To determine if the backend is connected?  If so, it's fine, but I'd
suggest being more explicit and calling it qemu_fe_is_be_connected().

Regards,

Anthony Liguori

>
>> 
>> Regards,
>> 
>> Anthony Liguori
>> 
>> >      void *opaque;
>> >      int idle_tag;
>> >      char *label;
>> > @@ -144,6 +145,17 @@ void qemu_chr_fe_open(struct CharDriverState
>> > *chr);
>> >  void qemu_chr_fe_close(struct CharDriverState *chr);
>> >  
>> >  /**
>> > + * @qemu_chr_fe_post_load:
>> > + *
>> > + * Indicate to backend that a migration has just completed. Must
>> > be called when
>> > + * the vm is in the running state.
>> > + *
>> > + * @connected true if frontend is still connected after migration,
>> > false
>> > + * otherwise.
>> > + */
>> > +void qemu_chr_fe_post_load(struct CharDriverState *chr, int
>> > connected);
>> > +
>> > +/**
>> >   * @qemu_chr_fe_printf:
>> >   *
>> >   * Write to a character backend using a printf style interface.
>> > diff --git a/qemu-char.c b/qemu-char.c
>> > index 4e011df..42c911f 100644
>> > --- a/qemu-char.c
>> > +++ b/qemu-char.c
>> > @@ -3390,6 +3390,13 @@ void qemu_chr_fe_open(struct CharDriverState
>> > *chr)
>> >      }
>> >  }
>> >  
>> > +void qemu_chr_fe_post_load(struct CharDriverState *chr, int
>> > connected)
>> > +{
>> > +    if (chr->chr_post_load) {
>> > +        chr->chr_post_load(chr, connected);
>> > +    }
>> > +}
>> > +
>> >  void qemu_chr_fe_close(struct CharDriverState *chr)
>> >  {
>> >      if (chr->chr_guest_close) {
>> > --
>> > 1.8.1.4
>> 
>> 
>>