[Xen-devel] [PATCH V5] libxenstore: filter watch events in libxenstore when we unwatch

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Julien Grall writes ("[PATCH V5] libxenstore: filter watch events in 
libxenstore when we unwatch"):
> XenStore puts in queued watch events via a thread and notifies the user.
> Sometimes xs_unwatch is called before all related message is read. The use
> case is non-threaded libevent, we have two event A and B:
>     - Event A will destroy something and call xs_unwatch;
>     - Event B is used to notify that a node has changed in XenStore.
> As the event is called one by one, event A can be handled before event B.
> So on next xs_watch_read the user could retrieve an unwatch token and
> a segfault occured if the token store the pointer of the structure
> (ie: "backend:0xcafe").
> 
> To avoid problem with previous application using libXenStore, this behaviour
> will only be enabled if XS_UNWATCH_FILTER is given to xs_open.
> 
> Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>

Acked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Committed-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel