kwin_wayland xdgv6: crash on ping

[Martin Flöser]

Am 2017-08-02 18:44, schrieb Marco Martin:
> Hi all,
> reporting it here my latest findings on a crash in the xdgv6 branch in 
> kwin,
> which i think it *may* reveal something else wrong besides the 
> implementation
> of the thing that it's crashing in particular (ping)
> when there are many windows opening and closing, we have a kwin crash 
> with the
> backtrace pasted below.
> 
> I get it mostly while using the file open dialog (like typing on the 
> file name
> textbox, i guess the culript is the suggestion dropdown window 
> appearing and
> disappearing several times)
> instead, on David machine it seems to happen mostly after opening and 
> closing
> several times kickoff
> 
> the crash at
> /home/diau/git/kf5/frameworks/kwayland/src/server/xdgshell_v6_interface.cpp:365
> 0x00007f6fb5b8c0a2 in zxdg_shell_v6_send_ping (resource_=0x1e908a0,
> serial=713)
> 
> suggests that resource is not valid anymore.
> down the stack, the chain of events happened after one window has been 
> closed
> and the next one should be activated

it's important to check whether the resource is still valid prior to 
sending in events. We do that for Resources everywhere. There we have 
the unbound event which sets the resource to null and the various 
requests check whether it is null.

So far we never send requests on the global, so it's possible that we 
don't track the unbinding of the resource correctly there. I suggest to 
disable ping till that's sorted (as mentioned before I consider the ping 
interface pointless in modern threaded applications anyway).

Cheers
Martin