Hi,
On Fri, Apr 22, 2016 at 04:47:48PM +0200, Pavel Grunt wrote:
> When channel is unref'ed during migration migrate_channel_event_cb
> is called causing a crash by coroutine yielding to nonexistent channel.
>
> As comment in spice_channel_coroutine says:
> Co-routine exits now - the SpiceChannel object may no longer exist,
> so don't do anything else now unless you like SEGVs
>
> Related: rhbz#1318574
> ---
> src/spice-channel.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/src/spice-channel.c b/src/spice-channel.c
> index 19237b3..7b0a3dc 100644
> --- a/src/spice-channel.c
> +++ b/src/spice-channel.c
> @@ -2296,6 +2296,7 @@ static gboolean spice_channel_delayed_unref(gpointer data)
> SpiceChannel *channel = SPICE_CHANNEL(data);
> SpiceChannelPrivate *c = channel->priv;
> gboolean was_ready = c->state == SPICE_CHANNEL_STATE_READY;
> + SpiceSession *session;
>
> CHANNEL_DEBUG(channel, "Delayed unref channel %p", channel);
>
> @@ -2303,6 +2304,13 @@ static gboolean spice_channel_delayed_unref(gpointer data)
>
> c->state = SPICE_CHANNEL_STATE_UNCONNECTED;
>
> + session = spice_channel_get_session(channel);
> + if (spice_session_is_for_migration(session)) {
> + /* error during migration - abort migration */
> + spice_session_abort_migration(session);
> + return FALSE;
> + }
> +
Just to be sure if I got it right. The migration fails for some reason which
triggers and error in the migration process for spice-gtk. That will make the
channel for the target host to be delayed_unref.
If we don't spice_session_abort_migration() now, migrate_channel_event_cb() will
be called for the channel for the former host which will try to yield to a
coroutine and cause the crash.
Does this only happen under failure in the migration like [0] or it could happen
if we do cancel the migration in the right moment?
[0] https://bugs.freedesktop.org/show_bug.cgi?id=92019
Cheers,
toso
> if (c->event != SPICE_CHANNEL_NONE) {
> g_coroutine_signal_emit(channel, signals[SPICE_CHANNEL_EVENT], 0, c->event);
> c->event = SPICE_CHANNEL_NONE;
> --
> 2.8.1
>
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