Subject: Re: [PATCH] cxl: Allow release of contexts which have been OPENED but not STARTED

From: Michael Neuling <[email-masked]>
Date: Tue, 18 Aug 2015 09:23:10 -0700

On Tue, 2015-08-18 at 19:19 +1000, Michael Ellerman wrote:
> On Tue, 2015-08-18 at 16:30 +1000, Andrew Donnellan wrote:
> > If we open a context but do not start it (either because we do not attempt
> > to start it, or because it fails to start for some reason), we are left
> > with a context in state OPENED. Previously, cxl_release_context() only
> > allowed releasing contexts in state CLOSED, so attempting to release an
> > OPENED context would fail.
> > 
> > In particular, this bug causes available contexts to run out after some EEH
> > failures, where drivers attempt to release contexts that have failed to
> > start.
> > 
> > Allow releasing contexts in any state other than STARTED, i.e. OPENED or
> > CLOSED (we can't release a STARTED context as it's currently using the
> > hardware).
> > 
> > Cc: [email-masked]
> > Fixes: 6f7f0b3df6d4 ("cxl: Add AFU virtual PHB and kernel API")
> > Signed-off-by: Andrew Donnellan <[email-masked]>
> > Signed-off-by: Daniel Axtens <[email-masked]>
> > ---
> >  drivers/misc/cxl/api.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c
> > index 6a768a9..1c520b8 100644
> > --- a/drivers/misc/cxl/api.c
> > +++ b/drivers/misc/cxl/api.c
> > @@ -59,7 +59,7 @@ EXPORT_SYMBOL_GPL(cxl_get_phys_dev);
> >  
> >  int cxl_release_context(struct cxl_context *ctx)
> >  {
> > -	if (ctx->status != CLOSED)
> > +	if (ctx->status == STARTED)
> >  		return -EBUSY;
> 
> So this doesn't break when you add a new state, is it worth writing it as:
> 
> 	if (ctx->status >= STARTED)
> 		return -EBUSY;
> 
> ?

Yeah I think that would be more future proof, although it won't make a
difference with the current code.

FWIW, looks good to me.

Mikey