[Spice-devel] [PATCH 0/3] RfC: fix locking

[Gerd Hoffmann]

On 04/28/11 13:14, Alon Levy wrote:
> On Thu, Apr 28, 2011 at 12:13:07PM +0200, Gerd Hoffmann wrote:
>>    Hi folks,
>>
>> Here is a alternative approach to fix the qemu locking issue.  It simply
>> handles the updates in the display refresh timer instead of switching
>> back and forth between the threads using the pipe.
>>
>> comments?
>
> Looks good. I guess you are sure that the lock is less resource hungry then
> switching threads?  Anyhow it's way less code, which is great.

Yes, the main point of doing it this way is to avoid thread context 
switches.

Beside that even the pipe version needs a lock for the update pointer 
variable (which is accessed in non-atomic ways from both iothread and 
spice-server thread context), i.e. it is buggy as-is.  The race window 
is pretty small and probably hard to hit though, guess thats why no 
issues showed up so far in practice.

cheers,
   Gerd