[Cbe-oss-dev] spufs poll issues

[Luke Browning]

On Tue, 2007-11-27 at 10:32 +0100, Arnd Bergmann wrote:
> On Tuesday 27 November 2007, Christoph Hellwig wrote:
> > Currently the poll methods on spufs all call spu_acquire which turns
> > into a mutex_lock on ctx->state_mutex.  Unfortunately ->poll isn't
> > actually allowed to block (although I can't really find a good reason
> > for that).  Looks like we're in a bit of a problem here.
> 
> Where is it documented that ->poll can't block? Is that just common
> knowledge or is there a WARN_ON() or so in the code that actually
> prevents us from blocking?
> 

poll is not supposed to wait for events (i/o) to happen, but it is
required to atomically access kernel data.  It therefore needs to take
locks and may block for a lock. 

Luke