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Re: [libvirt] [libvirt-glib 4/5] mainloop: protect 'handles' and 'timeouts' against concurrent accesses



On Wed, Jun 20, 2012 at 12:29:50PM +0200, Christophe Fergeau wrote:
> Timeout and watch deletion is done from an idle callback. However,
> we cannot assume that all libvirt event calls (the callbacks passed
> to virEventRegisterImpl) will be done from the mainloop thread. It's
> thus possible that a libvirt event call will run a thread while
> one of the idle deletion callbacks runs.
> Given that the 'handles' and 'timeouts' arrays are shared among all
> threads, we need to make sure we hold the 'eventlock' mutex before
> modifying them.
> ---
>  libvirt-glib/libvirt-glib-event.c |    8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/libvirt-glib/libvirt-glib-event.c b/libvirt-glib/libvirt-glib-event.c
> index c2eeb7a..587a59e 100644
> --- a/libvirt-glib/libvirt-glib-event.c
> +++ b/libvirt-glib/libvirt-glib-event.c
> @@ -255,11 +255,15 @@ _event_handle_remove(gpointer data)
>  {
>      struct gvir_event_handle *h = data;
>  
> +    g_mutex_lock(eventlock);
> +
>      if (h->ff)
>          (h->ff)(h->opaque);
>  
>      g_ptr_array_remove_fast(handles, h);
>  
> +    g_mutex_unlock(eventlock);
> +
>      return FALSE;
>  }
>  
> @@ -404,11 +408,15 @@ _event_timeout_remove(gpointer data)
>  {
>      struct gvir_event_timeout *t = data;
>  
> +    g_mutex_lock(eventlock);
> +
>      if (t->ff)
>          (t->ff)(t->opaque);
>  
>      g_ptr_array_remove_fast(timeouts, t);
>  
> +    g_mutex_unlock(eventlock);
> +
>      return FALSE;
>  }

ACK, clear thread safety bug


Daniel
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