Re: [AD] Fixed small problem with X11 acquire_screen

[Peter Wang <tjaden@xxxxxxxxxx>]

Chris wrote:

> Elias noticed that there was still continuing problems with deadlocks 
> in the GUI, though they were rarer. The backtrace showed that the 
> mouse/timer thread was waiting on an XLOCK/acquire_bitmap while the 
> bg/input thread was waiting on its own XLOCK. I traced the problem to 
> _xwin_lock. I was setting the locked thread id before actually locking 
> the thread, so if a context switch happened at just the right moment 
> when two threads were trying to lock the screen, the program would 
> become confused and deadlock.
>
> I committed a small change, switching lines 143 and 144 of 
> src/x/xvtable.c to set the locked thread id after the thread is 
> locked, which seems to fix the problem.


Cheers for that.  I wanted to look into this but never did.  If there 
are any more problems, what do you think about switching to a recursive 
mutex instead of XLockDisplay?

Peter