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

[Alon Levy]

On Thu, Apr 28, 2011 at 01:26:38PM +0200, Gerd Hoffmann wrote:
> 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.

I don't think it was, even without locking, but that's moot with your better
solution.

> 
> cheers,
>   Gerd
> 
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